case studies on change of use to dwellings...

Case studies on change of use to dwellings Final report on four case studies on the conversion of buildings into dwellings: BD2416

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Case studies on change of use to dwellings Final report on four case histories on the conversion of buildings into dwellings: BD2416

Dr Trevor J Hickman, BSc (Hons), MSc, PhD, MIOA

Sound Research Laboratories Limited

Department for Communities and Local Government

This research was commissioned by the previous government. The views and analysis expressed in this report are those of the authors and do not necessarily reflect those of the Department for Communities and Local Government. This document is being published in the interests of transparency. Department for Communities and Local Government Eland House Bressenden Place London SW1E 5DU Telephone: 030 3444 0000 Website: www.communities.gov.uk © Queen’s Printer and Controller of Her Majesty’s Stationery Office, 2011 Copyright in the typographical arrangement rests with the Crown.

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Contents

Contents ................................................................................................................................................. 3 Summary ................................................................................................................................................ 6 Case History 1: Conversion of Victorian Mill Building into Apartments............................................... 10 Existing Building ................................................................................................................................... 10 Outline of Proposed Development ....................................................................................................... 10 Second Floor Layout Plan........................................................................................ 12 Figure 1.1.............................................................................................................................................. 12 Design................................................................................................................................................... 13

Separating Floor Construction ...................................................................................................... 13 Separating Wall Construction........................................................................................................ 15 Internal Walls................................................................................................................................. 18 External walls ................................................................................................................................ 18 Staircase ....................................................................................................................................... 19 Separating walls between apartments and common areas .......................................................... 20 Doors............................................................................................................................................. 20 Roof Junction ................................................................................................................................ 20 Floor beams .................................................................................................................................. 21 Pipework........................................................................................................................................ 22 Common Areas ............................................................................................................................. 23 Thermal Requirements.................................................................................................................. 23

Pre-Completion Testing........................................................................................................................ 23 Measured Sound Insulation .......................................................................................................... 23 The measured sound insulation met the requirements of the new Regulations........................... 24

Costs..................................................................................................................................................... 24 Case History 2: Conversion of a Health Centre and Former Cottage Hospital into Terraced Houses and Bungalows ..................................................................................................................................... 26 Existing Building ................................................................................................................................... 26

Photograph 2.1 – Frontage of the Original Cottage Hospital ........................................................ 26 Figure 2.1 – Layout of the Health Centre ...................................................................................... 27

Outline of Proposed Development ....................................................................................................... 28 Chimneys were removed and blocked up. .................................................................................... 28 Figure 2.2a - Ground Floor............................................................................................................ 29 Photograph 2.2 – Frontage of the Redeveloped Cottage Hospital ............................................... 30 Figure 2.2b - Ground and First Floor of Victorian Block................................................................ 30

Design................................................................................................................................................... 31 Separating Wall Construction........................................................................................................ 31 Internal Walls................................................................................................................................. 33

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Internal Floors ............................................................................................................................... 35 Junctions Between Separating Walls and Roofs .......................................................................... 35 Figure 2.10 – Section Through Units 1 - 3 .................................................................................... 38 Internal Floors ............................................................................................................................... 40 Staircase ....................................................................................................................................... 41 Services......................................................................................................................................... 41 Thermal Requirements.................................................................................................................. 41

Pre-Completion Testing........................................................................................................................ 42 Measured Sound Insulation .......................................................................................................... 42 The measured sound insulation met the requirements of the new Regulations........................... 43

Costs..................................................................................................................................................... 43 Case History 3: Conversion of Mid-Terrace Dwelling House/Shop into Flats..................................... 45 Existing Building ................................................................................................................................... 45

Photograph 3.1 – Frontage of Terraced Houses .......................................................................... 45 Figure 3.1 – Existing Ground and First Floor Plans ...................................................................... 46 Measured Sound Insulation before Conversion............................................................................ 47

Outline of Proposed Development ....................................................................................................... 47 Figure 3.2 - Layout of the Ground and First Floor Flat.................................................................. 48

Design................................................................................................................................................... 48 Separating Floor Construction ...................................................................................................... 48 Separating Walls ........................................................................................................................... 49 Internal Walls................................................................................................................................. 49 External Walls ............................................................................................................................... 50 Separating Walls between Flats and Common Areas .................................................................. 51 Doors............................................................................................................................................. 52 Internal Floors ............................................................................................................................... 52 Common Areas ............................................................................................................................. 52 Services......................................................................................................................................... 53 Thermal Requirements.................................................................................................................. 53

Pre-Completion Testing........................................................................................................................ 54 Measured Sound Insulation .......................................................................................................... 54 The Measured Sound Insulation Met the Requirements of the New Regulations ........................ 55

Costs..................................................................................................................................................... 55 Case History 4: Conversion of Detached Dwelling House to Flats and Bedsits ................................. 57 Existing Building ................................................................................................................................... 57

Photograph 4.1 – The front façade of the detached House.......................................................... 57 Figure 4.1 – Ground and First Floor Plans of Existing Building .................................................... 58

Outline of Proposed Development ....................................................................................................... 59 Figure 4.2a .................................................................................................................................... 60 Figure 4.2b .................................................................................................................................... 61

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Figure 4.2c .................................................................................................................................... 62 Design................................................................................................................................................... 63

Separating Floor Construction ...................................................................................................... 63 Separating Walls ........................................................................................................................... 65 Internal Walls................................................................................................................................. 66 External Walls ............................................................................................................................... 67 Separating Walls between Flats and Common Areas .................................................................. 68 Doors............................................................................................................................................. 69 Common Areas ............................................................................................................................. 69 Services......................................................................................................................................... 70 Thermal Requirements.................................................................................................................. 70

Pre-Completion Testing........................................................................................................................ 71 Measured Sound Insulation .......................................................................................................... 71 The measured sound insulation met the requirements of the new regulations ............................ 72

Costs..................................................................................................................................................... 73 Appendix 1............................................................................................................................................ 74 Appendix 2............................................................................................................................................ 75 Appendix 3............................................................................................................................................ 77

Table A3.1 – Summary of Sound Insulation Achieved by Constructions Studied ........................ 78

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Summary

• On 1 July 2003 changes were made to Part E of the Building Regulations which required higher acoustic standards. This applies to new build constructions and buildings converted for residential use, which includes student accommodation, hotels and residential homes. This document comprises case histories describing the construction work to change four different buildings into dwellings. The completed dwellings were tested and all fully met the requirements of Part E of the Building Regulations.

• The types of building that were converted, their construction and the measures used to create separating walls and floors are outlined here. More detailed descriptions are given in the case histories themselves. The aim is to demonstrate the typical changes necessary to satisfy the 2003 requirements. This should help builders wanting to make similar conversions, although exact constructions required will vary from case to case.

• Case History 1: Conversion of Victorian Mill Building to Apartments

- Existing construction: Heavy masonry walls with timber beam and joist floors and more recent studwork partition walls.

- Separating walls: New metal stud partitions.

- Separating floors: Existing floors upgraded with timber floating floor and suspended plasterboard ceiling.

• Case History 2: Conversion of Single Storey Health Centre and former Cottage Hospital to Terraced Houses and Bungalows.

- Existing construction: Mixture of solid and external cavity brick walls.

- Separating walls: A mixture of the following:

o Independent plasterboard lining to existing half brick walls.

o New timber stud partitions.

o Existing solid brick walls with length of cavity blockwork infill.

o Existing solid brick walls extended up with solid blockwork.

- Separating floors: None.

- Internal floors: New timber joist internal floor formed to create two storey houses.

• Case History 3: Conversion of Mid-Terraced Dwelling House/Shop to Flats

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- Existing construction: Mixture of solid and external cavity brick walls with timber joist floors. Some timber stud internal walls.

- Separating walls: Existing 225mm solid brickwork replastered and half brick walls provided with independent plasterboard lining on a timber frame.

- Separating floors: Existing timber joist floors upgraded including mineral wool quilt put between joists. Existing ceilings upgraded with extra plasterboard and in addition a second plasterboard mf ceiling suspended below via proprietary acoustic hangers.

• Case History 4: Conversion of Detached Dwelling House to Flats and Bedsits.

- Existing construction: Solid brick walls with some internal timber stud partitions. Timber joist floors with timber floating floor.

- Separating walls: Independent plasterboard lining on metal studs to existing brick walls. Existing timber stud partition upgraded and then independent plasterboard lining.

- Separating floors: Two designs for separating floor.

o A new proprietary isolated floor and ceiling system.

o Floating floor removed and mineral wool put between the joists of existing timber joist floor. Suspended mf plasterboard ceiling added with further mineral wool quilt.

• Each case history not only describes the design of the separating wall and floor, but also the treatment of other construction elements necessary to meet the requirements of Part E of the Building Regulations.

- Internal (non-separating) walls and floors.

- External walls.

- Doors.

- Service penetrations.

- Finishes in common areas.

• Information is also given on the following:

- The sound insulation measured in the completed building.

- Where available, the results of sound insulation tests before building work started.

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• A brief review of the acoustic construction details in relation to the thermal insulation and ventilation requirements in Parts L1 and F of the Building Regulations.

• Estimated costs of the constructions affected by the requirements of Part E. Costs were current early in the year 2005.

• It is essential to realise that the sound insulation achieved in the completed building does not only depend on the separating wall or floor construction. Sound travelling indirectly via other elements of the building, such as the inner leaf of the external wall, can be as important and sometimes more so. This is known as flanking sound transmission and measures to control it are discussed in each of the case histories.

• Flanking and transmission is a much more frequently encountered problem in conversions than in new build. The following are common flanking paths where one must be wary and take measures to reduce flanking sound.

• Existing internal walls which continue past the separating floor. With heavy walls, equivalent to a full brick (225mm) wall, flanking sound is not excessive. For lighter walls there may be a problem.

• Inner leaf of an external cavity wall in flats. An inner leaf of lightweight blockwork will carry excessive flanking sound past the separating floor. Even a heavier half brick wall would not be adequate where the separating floor is lightweight (timber) as a light floor offers negligible resistance to sound travelling up or down the wall.

• The inner leaf of the external wall can also carry sound past a separating wall. In new build there is usually a break in the inner leaf at the separating wall line. However, in conversions, new separating walls often abut an existing unbroken inner leaf.

• Lightweight concrete floors, floating screeds or timber floors allow excess flanking if they are continuous under separating walls. Again, breaks in the structure are designed into new buildings, but are often impractical with an existing structure. The flanking is worse with lightweight stud frame separating walls, which are normally used in conversions where a new wall is to be built.

• Above the top floor, roof voids, existing ceilings and joists can be serious flanking paths when new separating walls are introduced. Although the wall can readily be continued up to close the roof void and a break made in the ceiling, it is probably not practical to make a break in the existing joists.

• Some general information not relating to any one particular case history is given in Appendices.

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• Appendix 1 explains the approximate relationship between the airborne sound insulation measured on site (DnT,w + Ctr) and the laboratory rating (Rw + Ctr) of a separating wall or floor construction.

• Appendix 2 gives information on the requirements for sound absorbing finishes in common areas of flats and an example calculation.

• Appendix 3 explains about the requirement for pre completion testing and the limits set It also gives a summary of the measured sound insulation values on completion of all four case histories.

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Case History 1: Conversion of Victorian Mill Building into Apartments

• There are some features for reducing flanking and of particular interest in this case history.

• Although the very heavy masonry construction required few measures to control flanking sound, the existing timber floor was potentially a serious weakness. A timber floating floor on resilient battens and suspended ceiling gave adequate control of sound travelling along the floor past metal stud separating walls.

• The design of the separating wall junction with the sloping roof to control flanking sound transmission.

• Using the suspended ceiling to encase the large timber floor beams.

Existing Building

• The existing building comprised:

- Solid brick external walls from 600mm to 450mm thick.

- Windows set in the external wall at regular intervals.

- A pitched tiled roof with dormer windows at the top floor level.

- Boarded timber joist floors with the joists set at right angles to timber beams supported from brick walls.

- Plaster on lath ceilings.

- Open floor areas.

- Some lengths of internal, 680mm brick walls. These were originally designed to carry the loads of heavy machinery and to support timber floor beams.

Outline of Proposed Development

• Much of the floor structure was to be kept, incorporating it into the new separating floors. Lightweight internal partitions were removed.

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• The plaster ceilings were generally damaged or in poor condition, so they were mostly to be replaced with plasterboard ceilings.

• The separating walls were to be new and had to be lightweight to limit the additional load on the structure.

• Internal walls within apartments were mostly new. A few retained brick walls were incorporated as internal walls between different rooms in the same apartment and between apartments and common areas.

• A new concrete block stairwell was created at the end of the building

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First Floor Layout Plan

Second Floor Layout Plan

Figure 1.1

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Design Separating Floor Construction

• The existing floors would not give adequate sound insulation, so were upgraded as shown in figure 1.2.

• A proprietary floating floor system was used. This improved vertical airborne and impact sound transmission and also horizontal flanking transmission along the floor. The system chosen had an acoustic rating of Lw = 25dB (with mineral wool). These ratings measure the floating floor performance on a concrete base floor. They are not directly applicable to timber floors, where the performance will be much lower, but do allow a rough comparison of systems.

• The floating floor stopped either side of partitions which were built off the existing structure, as shown in Figure 1.3. This reduced sound leaking through the junction between the base of the wall and the existing structure.

• Flooring was 18mm chipboard supported on resilient battens giving a 50mm cavity between the new flooring and the existing floor structure. The battens had an expanded plastic layer along one length.

• The void between battens was filled with mineral wool quilt within 300mm of the external and separating walls. This further reduced sound leakage at the perimeter of the floating floor.

• 100mm thick mineral wool quilt (12 kg/m3 density) was laid in the main floor void between the joists., This thickness quilt was increased to the full joist depth of 200mm beneath, and 300mm either side of the separating wall lines and within 300mm of external walls (figure 1.3). The effect of this mineral wool was to improve the airborne sound insulation of the floor.

• The existing 30mm lath and plaster ceiling was kept where practicable to do so. Where it was removed it was replaced with two 15mm layers of dense plasterboard (26 kg/m2) fixed directly to the underside of the joists.

• The additional ceiling was one layer of 12.5mm standard wallboard (9 kg/m2) attached to the existing joists/ceiling via a metal frame suspension system. The depth of the cavity formed between the two ceilings was approximately 150mm.

• As with the floated floor, the suspended ceiling stopped either side of each partition, enclosing the head deflection detail. The detail to accommodate downward deflection was formed by fixing the head channel through a 25mm plasterboard fillet and the upper ceiling to noggins between joists. The fillet was sealed to the ceiling using intumescent mastic and the suspended ceiling to the partitioning using a flexible acoustic sealant. The head detail was

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cloaked using continuous metal angle and the suspended ceiling further reduced any sound leaking through the junction. The construction detail is shown on Figure 1.4.

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Figure 1.2 - Typical Vertical Section Through Separating Floor

18mm chipboard

Resilient Battens

25mm floor boards - reused

Existing joists (approx 200mm deep)

100mm mineral wool quilt

2 x 15mm dense plasterboardor 30mm lath and plaster

Strap hanger and channel

12.5mm wallboard

Variable cavity (approx 150mm)

Separating Wall Construction

• The separating walls were new and a proprietary metal stud system was chosen. This was 90mm metal studs at 600mm centres clad with two layers of 15mm dense plasterboard (26 kg/m2) and 75mm of mineral wool (12 kg/m3 density) in the cavity between the studs. This had a laboratory rating of (Rw + Ctr ))= 51dB. (This choice of noise rating is explained in Appendix 1.)

• In a building conversion, there is a temptation to design the size and layout of apartments without consideration of the location of window openings in the external façade. If separating walls meet the external façade at a window opening, it is impracticable to achieve the required sound insulation whilst retaining the window. Similarly, if the ceiling height is to be lowered, the new ceiling line may drop below the head of the window opening.

• The separating walls had a number of light switches and electrical sockets installed. These were not placed ‘back to back’, or were boxed in with plasterboard, to minimise sound leakage.

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Figure 1.3 - Junction of Separating Floor and Wall (Base)

2 x 15mm dense plasterboard eachside of 90mm metal studs

3 x 25mm Mineral Wool Quilt

Sealing Strip

18mm chipboardResilient Battens25mm Mineral Wool Quilt25mm Existing boarding (reused cut)

2 x 100mm Mineral Wool Quilt(close to separating wall line)

2 x 15mm dense plasterboard

Metal channel

12.5mm wallboard

Plasterboard filletMetal angle

Note: 25mm deflection head detail - seek advicefrom specific partition system supplier

Figure 1.4 - Junction of Separating Floor and Wall (Head)

16

• The T-junction between a wall separating apartments and the separating wall to the corridor/common area was constructed to limit flanking sound transmission along the corridor/common area wall. This was as shown in figure 1.5. It follows the advice of the manufacturer.

Figure 1.5 - Plan Section of Junction Between Separating Walls

CommonHallway

SeparatingWall

17

Internal Walls

• The internal wall construction comprised 70mm metal studs at 600mm centres with a single layer of 12.5mm standard plasterboard (9 kg/m2) on each side and 25mm of mineral wool quilt in the cavity. This construction has a laboratory rating of 42dB Rw and meets the requirement in the Regulations for internal walls around bedrooms and rooms containing a water closet. For ease, this construction was used for all internal walls.

External walls

• The 450 – 600mm solid brick external walls were very heavy and adequate. It was not necessary to reduce flanking sound transmission along them.

• For the width of the partition the wall surface was given a thin coat of render to give a smooth surface against which the proprietary wall system was sealed. This is shown in Figure 1.6.

Render

External Wall

Figure 1.6 - Plan Section between Separating Wall and External Wall

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Figure 1.7 - Vertical Section of Junction betweenSeparating Floor and External Wall

Acoustic Sealant External Wall

• Where joists were perpendicular to the external wall, battens were fixed along the wall immediately below the level of the existing boarding. This helped to reduce sound leakage between the edge of the floor and the wall. To help further, the battens and boarding were sealed to the wall with mastic.

• Where ceilings were replaced, similar battens were fixed to the external wall immediately above the ceiling line and the new plasterboard ceiling fixed and sealed to them and to the wall.

Staircase

• The new staircase was constructed of dense concrete blocks (1900 kg/m3) laid flat to form a 215mm thick wall. This was plastered both sides. Damaged brickwork and redundant openings were also filled in using this construction. A good acoustic seal between the separating floors and these walls was made using similar details to the junction with external walls, shown in figure 1.7.

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Separating walls between apartments and common areas

• The walls separating apartments and common areas used the same construction as separating walls between apartments.

Doors

• The Regulations state that doors to common areas should have a mass of at least 25 kg/m2 and have good perimeter sealing all round. Solid timber doors were used. The entrances to all the apartments had a small lobbied hallway that protected the other rooms from noise intrusion.

Roof Junction

• The roof was supported on existing sloping timber rafters. 80mm of thermal insulation was sprayed under the roof between the rafters. This did not contribute to the sound insulation, from which point of view mineral wool would have been better.

• At the separating wall line a single layer of the 12.5mm dense plasterboard (11 kg/m2) was fixed between adjacent joists on either side. The separating wall was then fixed and sealed to this board.

• The lining was fixed last, hung from the joists via metal furring, effectively like a ceiling. The lining overlapped the single board between joists, being separated from it with the metal furring fixed through the board to the joist. The lining was sealed against the separating wall. Figure 1.8 shows a plan section through this junction. The lining was two layers of 12.5mm dense plasterboard (22 kg/m2). This thickness was required to limit traffic noise intrusion through the roof and not to satisfy the Regulations. The Building Regulations do not cover noise break-in from external sources. However, the double layer of boarding did further reduce noise flanking through the roof void.

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Figure 1.8 - Plan Section of Junction Between Separating Wall and Sloping Roof

RaftersTiles

Battens

Thermal Insulation

12.5mm standard ordense wallboard

Strap and channel

2 x 12.5mm denseplasterboard (sloped to follow line of roof)

3 x 25mmMineral Wool Quilt

2 x 15mm dense plasterboard

Sarking

Floor beams

• The floor beams supporting the joists were deeper and in places projected below the ceiling line. This presented a possible flanking sound path through the beam, which was as wide as the partition. A movement joint, up to 10mm, was incorporated. The suspended ceiling level was lowered locally to take in these beams. The details of this junction are shown in figure 1.9.

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Figure 1.9 - Junction of Separating Wall and Floor Beam

Timber Beam

Channel

12.5mm wallboard

Pipework

• Pipework was taken through separating floors. This is a potential acoustic weakness. Of main concern were the living/kitchen rooms and bathrooms. Water and soil pipes were boxed in using 15mm dense plasterboard with a 25mm layer of mineral wool quilt lining two sides of the boxing. The boxing was supported off the main floor boarding, and not the floating floor. Similarly it was taken up above the suspended ceiling to the underside of the fixed ceiling. At the penetrations themselves, pipes were sleeved with mineral fibre fire stopping.

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Common Areas

• Under the Regulations, sound absorbing finishes must be installed in the common areas such as corridor, hallways and staircases. More details about these requirements, together with an example of the type of calculation that could be used, are given in Appendix 2.

• Carpet in common areas gave some sound absorption, but it did not come up to Class C. Therefore some additional absorption was provided by replacing half the suspended plasterboard ceiling with mineral fibre tile. Using a thick carpet on suitable foam underlay would also give adequate sound absorption.

Thermal Requirements

• The constructions of the external wall and roof do not meet the current requirements for thermal insulation as set out in Part L1 of the Building Regulations. A conversion being done now on a similar building shell would require additional insulation to the external walls and roof. These requirements do not necessarily apply to buildings listed as historic.

• The junction details do not cause thermal bridges, increase the risk of condensation or interfere with ventilation.

Pre-Completion Testing

• Pre-completion testing must be done on at least one in every ten units completed including the first ones, to show that the specified levels of airborne and impact sound insulation have been achieved.

• Before the building was handed over and occupied, sound insulation tests were done between a sample of rooms. Airborne and impact sound insulation was measured across the separating walls and floors between units A to D shown on Figure 1.1.

• Tests were done in accordance with BS EN ISO 140-4, 1998 and BS EN ISO 140-7, 1998.

Measured Sound Insulation

• The airborne sound insulation of the separating walls was measured from the living/kitchen room into the bedroom. The sound insulation of the separating floor was measured between a pair of living/kitchen rooms and a pair of bedrooms. The results are tabulated below.

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Source Room Receiving Room Element

Tested DnT,w + Ctr

dB

Limit

dB - min

Living/kitchen Room ( A )

Living/Kitchen Room ( C )

Living/Kitchen Room ( B )

Bedroom ( B )

Bedroom ( B )

Bedroom ( D )

Living/Kitchen Room ( D )

Bedroom ( D )

Wall

Wall

Floor

Floor

44

45

47

52

43

43

43

43

L’nT,w - dB dB - max

Living Room/Kitchen ( D )

Bedroom ( D )

Living Room/Kitchen ( B )

Bedroom ( B )

Floor

Floor

54

56

64

64

The measured sound insulation met the requirements of the new Regulations

• The impact sound insulation is well within the limits, the combination of floating floor and suspended ceiling being more than adequate for this purpose.

• The airborne sound insulation of the floor is potentially high. However, it would be risky to downgrade the floor construction as the floating floor and suspended ceiling are there to limit flanking sound being transmitted below and above the separating walls. The walls’ potential performance does not have a large margin and so flanking transmission control must be very good in both the design and workmanship

• The airborne sound insulation between living/kitchen rooms was lower than between bedrooms. This may have been due to a number of penetrations related to kitchen pipework.

Costs

• The cost of the constructions has been estimated. This includes those constructions affected by the requirements of Part E, that is the separating floors and walls, internal walls, pipework boxing and sound absorption in the hallway. It does not include doors, surface finishes, floor coverings (carpet), fittings and fixtures.

• The cost is the total cost of installing these items including a proportion of site facilities overheads and profit but excluding VAT. It has been shared between the flats, so it is the average cost per flat for those tested.

• The rounded total is £12,500 per flat plus £35/m2 for absorptive treatment to the hallway. The main items are

• Separating floors: £5,200

• Separating walls (to other flats and hallway): £3,100

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• Internal walls: £2,500

• These costs are for all the works described, not the additional cost of complying with the latest revision of Part E.

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Case History 2: Conversion of a Health Centre and Former Cottage Hospital into Terraced Houses and Bungalows

• There are some features of particular interest in this case history.

• Comparison of three different separating wall designs

• Incorporating a new internal floor to create some two storey dwellings, extending the separating wall into an old timber pitched roof.

• Junctions of both masonry and stud work separating walls with sections of flat woodwool slab roof.

Existing Building

• The existing building was originally a small Victorian Cottage Hospital, shown in Photograph 2.1. This was greatly extended in the 1950’s to provide single storey consulting rooms and offices around a central courtyard, as shown in Figure 2.1.

Photograph 2.1 – Frontage of the Original Cottage Hospital

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Figure 2.1 – Layout of the Health Centre

• The old Cottage Hospital building comprised:

- Cavity brick external walls with windows in the front façade. Some door and window openings had been made in the rear wall when the building was extended.

- A pitched tiled roof with gables at each end and set at right angles to the main roof. The main roof was supported via central posts between roof trusses and the apex.

- Internal brick walls, generally 240mm thick.

- Ventilated timber joist ground floors.

- Ceilings were plaster on lath.

• The existing 1950’s extension comprised:

- Cavity brick external walls with windows at frequent intervals

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- A flat wood wool slab roof, gently sloping down towards the central courtyard.

- Internal brick and half brick walls.

- Plasterboard ceilings on timber ceiling joists.

- Ventilated timber joist floors.


• The health centre has been redeveloped as one and two storey dwelling houses around a central courtyard. Much of the existing structure was kept.

• The newer part of the health centre was redeveloped as single storey dwelling houses.

• The layout of these units is shown on Figure 2.2a. It was arranged to allow many of the internal brick walls to be kept.

• Openings in thicker brick walls, previously for corridors or doorways, were filled in with two leafs of dense blockwork. Longer lengths of new separating wall and new internal walls were built in plasterboard on a stud framework.

• The structure of the flat roof to the newer block was kept but refurbished. Existing ceilings were removed and new plasterboard ceilings hung from existing joists.

• All timber joist ground floors were removed and replace with cast in-situ concrete.

• Chimneys were removed and blocked up.

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Figure 2.2a - Ground Floor

• The single storey Victorian building was made into three, two storey dwellings by opening up the roof space and installing a new floor with dormer windows in the pitched roof.

• The front elevation is shown in Photograph 2.2 and the layout of ground and first floors in Figure 2.2b.

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Photograph 2.2 – Frontage of the Redeveloped Cottage Hospital

Figure 2.2b - Ground and First Floor of Victorian Block

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Design

Separating Wall Construction

• The existing 240mm brick walls would give adequate sound insulation as separating walls. Where necessary they were replastered. Above ceiling level these walls were built up as near as practicable to the underside of the roof using 100mm dense concrete blockwork.

• The gap between roof and separating walls was closed off to further reduce sound transfer via the roof void and for fire separation. Junction details with the roofs are described further on.

• In the Victorian building an upper storey was created in the pitched roof void. The retained brick separating walls were extended upwards to form the first floor separating walls, and close off the remaining roof void. The new walls comprised two leafs of 100mm dense solid concrete blockwork mortared together to form a solid wall, nominally 210mm thick, and plastered to match in with the existing wall. The same wall was continued up to the underside of the pitched roof, although a single leaf would have been adequate above the first floor ceiling level.

• There were gaps in many of the existing brick walls where corridors or doorways had been in the earlier building. Where these became separating walls, the gaps were filled in with two leafs of 100mm dense solid concrete blockwork, which were plastered, see Figure 2.3. The cavity between the leafs varied to match the wall into the existing structure.

Figure 2.3 - New Blockwork Infill Separating Wall

12mm render + plaster skim

New ConcreteFloor

100mm dense solidconcrete block

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• Where separating walls were entirely new, these were made using plasterboard on studwork frames. The construction shown on Figure 2.4 is 300mm thick. It comprises independent 100 x 50mm timber stud frames clad with two layers of 12.5mm dense plasterboard (11 kg/m2) each side. In the cavity 50mm of flexible mineral wool (35 kg/m3) was hung between the frames. The boards were taped and finished with a skim coat of plaster.

Figure 2.4 - New Studwork Separating Wall

Plaster skim

2 x 12.5mm dense plasterboard

100 x 50 mm

Acoustic sealant

New ConcreteFloor

Timber studs

50mm flexible mineralfibre slab (35kg/m3)

(2 x 11kg/m2)

• Where a half brick wall was kept as part of a new separating wall (as between Units 5 and 6), it was upgraded with an independent plasterboard lining. This was in effect one side of the studwork wall spaced off the existing wall by approximately 150mm, giving an overall thickness of 300mm. This is shown on Figure 2.5.

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Figure 2.5 - Lining to Upgrade Retained Brick Wall

2 x 12.5mm dense

100 x 50 mm

Acoustic sealant

New ConcreteFloor

Retained PlasteredHalf Brick Wall

AdditionalSkimCoat

50mm flexible mineralfibre slab (35kg/m3)

timber studs

plasterboard (2 x 11kg/m2)

Internal Walls

• Many of the internal walls in these new units were retained brick and half brick walls. If internal walls are kept in conversion projects, they are not subject to the sound insulation requirement of Part E, that is a laboratory rating of 40dB Rw. Nevertheless, plastered brick and half brick walls, as retained on this site, achieve this standard.

• Generally, retained internal brick walls did not penetrate right through new studwork separating walls. A break was made in the existing brick wall so that the separating wall was continuous, rather than the internal wall.

• Between units 6 and 7 a new studwork separating wall was broken either side of an existing 240mm brick wall. However, the brick internal wall only penetrated through to the far side of the separating wall and did not continue into the adjacent dwelling, see Figure 2.6.

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Figure 2.6 - An atypical Junction between New Separating Wall and Retained Internal Wall (Plan Section)

New StudworkSeparating Wall

Retained 240mmPlastered Brick Wall(Internal Wall)

New Plaster

UNIT 7Dining Area

UNIT 7Bedroom

UNIT 6Lounge orbedroom

• Small gaps in internal walls, for example former doorways, were closed with one or two leafs of dense solid concrete blockwork to match the existing wall. These were finished with plaster.

• Larger lengths of new internal wall were constructed in plasterboard on a studwork frame. This comprised 100 x 50mm timber stud frame clad with one layer of 12.5mm plasterboard (10kg/m2) each side. In the cavity 50mm mineral fibre (35 kg/m3) was hung between the studs. The overall thickness was approximately 130mm. The construction is shown on Figure 2.7.

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Figure 2.7 - New Internal Wall

100 x 50mm

Acoustic sealant

New ConcreteFloor

1 x 12.5mm of plasterboard (10kg/m2)

timber studs

25mm mineral wool quilt (10kg/m3)

and skim

Internal Floors

• A new internal floor was incorporated in the Victorian building, Units 1 to 3. This comprised:

- 25mm flooring grade chipboard deck (17 kg/m2)

- 175 by 50mm timber joists at 400mm centres

- A ceiling of 12.5mm plasterboard (10 kg/m2) and skim. The construction complies with internal floor type C given in ADE 2003.

Suppliers can advise on the laboratory sound insulation rating of similar floor constructions incorporating their components.

Junctions Between Separating Walls and Roofs

• At this particular site the junction of the separating wall and the various roof types was an important factor in limiting flanking noise transmission between dwellings.

• In the single storey building, new studwork separating walls were built up to the underside of the flat roof. This was the retained wood wool slab, which was supported on timber joists. The wall therefore had to be taken up past the retained ceiling joists. Where ceiling joists were perpendicular to the line of the wall, the plasterboard of the partition was cut carefully around the joist and sealed with flexible mastic. A gap was left under the roof joist that was packed with mineral fibre to accommodate some vertical deflection of the roof and joist.

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• Similarly, the plasterboard had to be accurately cut round ceiling joists that penetrated the wall line and sealed to it with flexible mastic. Unlike the roof joists, no allowance for movement was necessary around these ceiling joists. A vertical section of this junction is shown in Figure 2.8.

Figure 2.8 - Junction of New Separating Wall with Underside Flat Roof

Water ProofingRetained Wood Wool Slab

Roof Joist

Strap HangerMineral Woolomitted for clarity

Ceiling ChannelNew 12.5mmPlasterboard Ceiling

New Separating Wall

250mmMineral Wool Quilt (10kg/m3)

Ceiling Joist250mmMineral Wool Quilt (10kg/m3)

Mineral Fibre in gapbetween board and roof joist

• With the masonry separating walls in the single storey building the blocks did not fit exactly to the line of the roof. The gap left was filled with flexible intumescent packing. A vertical section is shown in Figure 2.9.

36

Figure 2.9 - Junction of Retained Separating Wall with Underside of Flat Roof

Water ProofingRetained Wood Wool Slab

Mineral Woolomitted for clarity

Intumescent Packing

Dense Solid Concrete Blockwork

Retained Brickwall

250mmMineral Wool Quilt (10kg/m3)

Ceiling Joist

• The ceilings were 12.5mm plasterboard (10 kg/m2). These were important in maintaining high sound insulation, stopping sound travelling via the roof. Thermal insulation was placed on top of the ceilings. A total of 250mm mineral wool quilt (10kg/m3) was used which further reduced flanking sound via the roof junction. To achieve good sound insulation a 100mm quilt would have been adequate but would not have given as good thermal insulation.

• In the Victorian building the pitched roof was treated differently. Figure 2.10 is a section through the building showing how the additional storey was incorporated into the roof space.

• The thermal insulation was incorporated in the sloping roof up as far as the ceiling level. It comprised two urethane boards, one fixed between the rafters and the other under the rafters. This was faced with 12.5mm plasterboard (10 kg/m2). Above ceiling level, insulation was 250mm mineral wool quilt (10 kg/m3) laid on top of the ceiling.

37

Figure 2.10 – Section Through Units 1 - 3

• The new ceiling to the upper storey was fixed to new timber ceiling joists spanning between new steel purlins, which were supported at each end on a separating or external wall. The 12.5mm wallboard was continued down as a facing to the rafters to form the sloping walls of the first floor rooms. The arrangement is shown in Figure 2.11, which is a section not on a separating wall line.

38

Figure 2.11 - Units 1 - 3, Junction of Roof and Ceiling, off Separating Wall Line

250mm Mineral Wool(10kg/m3)

Ceiling joist

12.5mm plasterboardceiling

Battens

Counter Battens

90mm polyisocyanurate board between rafters

12mm plasterboard

40mm polyisocyanurate board under rafters

• The separating walls in the Victorian building were all masonry. These were extended full height into the roof void and cut as far as practicable to follow the line of the pitched roof. Any gaps on the separating wall line between the wall and roof and between battens was filled with intumescent packing.

• The separating walls penetrated through the plasterboard that lines the underside of the roof, finishing between the rafters. The plasterboard lining, forming the sloping walls of the rooms, was therefore discontinuous each side of the separating wall. This was essential if it was not to form a flanking path across the separating wall.

• Openings were left in the blockwork of the separating walls to carry the steel purlins. These were bedded on mortar. As steel is a good carrier of sound a gap was left between the purlins. The void around the steel was then packed in the middle with mineral fibre (35 kg/m3) and then finished with mortar to the full depth of the separating wall. The purlins were then faced with wallboard between the ceiling and sloping walls. The arrangement is shown in Figure 2.12.

39

Insulation Omittedfor Clarity

Mineral fibre (35kg/m3)

Ceiling Joist

Steel PurlinMortar Infill

New Dense Concrete Blockwork

Retained Brick Wall

12.5mm plasterboard ceiling

Figure 2.12 - Units 1 - 3, Junction of New Roof Purlins and Extended Separating Wall External Walls

• The external walls were cavity brick with a plaster finish. The cavity was closed on the separating wall lines with mineral fibre fire stopping. The walls needed no other upgrading to reduce flanking noise transmitted along them.

• In the Victorian building, one of the separating walls lined up with a window in the rear façade. So that the courtyard gardens had some privacy, the window openings on this façade were filled in with blockwork. Dense concrete blocks provided a suitable surface against which to build the separating wall. Separating walls must not be built against window openings as the sound insulation will be seriously degraded by flanking and inadequate sealing.

Internal Floors

• The existing suspended timber ground floors would have provided a flanking sound path under lightweight separating walls. The decision to replace them all with concrete avoided this potential problem.

40

• The new internal floor in the Victorian building was lowered relative to the existing ceiling. This aligned it below the head of the ground floor windows on the front façade. Such a junction would reduce the sound insulation. Near the front façade the floor level was stepped up above the window head forming a bulkhead.

• On the first floor the small step in the floor level was hidden by boxing in the space above the step and below the level of the window-sill. This formed a continuous shelf across the room and also extended horizontally into the dormer window opening. This arrangement can be seen in Figure 10. It was essential that the void formed was totally closed off and sealed at each separating wall line.

Staircase

• The new stairs in the Victorian building were kept away from the separating walls. This reduced structure borne impact noise from people going up and down the stairs being carried horizontally into the dwelling next door. This is a particular problem with solid separating walls as in this building. This aspect of noise control is not covered by ADE 2003, but should be considered if the aim is good sound insulation in general.

Services

• No pipework or other services were taken through the separating walls. The potential degradation of sound insulation if such penetrations are not adequately treated was not a consideration at this site.

• Electric sockets were staggered on either side of studwork separating walls with at least one pair of studs between. The gap between the timber studs on either side of the wall was fully filled with mineral fibre.


• The change from health centre to dwellings is a material change of use and with respect to “Conservation of Fuel and Power” is covered under Part L1 of the Building Regulations. Thermal requirements relate to the external envelope of the building, which is a factor in sound insulation because it can allow flanking sound transmission between dwellings. However, as this report is primarily about satisfying Part E, there is no information given about lighting, heating systems or new windows.

• There is a requirement for new building elements such as the roof, to meet the elemental standards for transmission of heat. The insulation in the roof elements is satisfactory. None of the alterations to the building have been included in this report because of their affect on acoustics conflict with thermal insulation requirements.

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• Pre-completion testing must be done on at least one in every ten units completed, including the first ones, to show that the specified levels of airborne and impact sound insulation have been achieved. If a different construction is used for some of the separating walls (or floors) within a development, these must be treated separately with further tests done on each type of construction.

• This development was started before the new regulations came into force, and pre-completion testing was not required by Building Control. Nevertheless, sound insulation was measured between some of the dwellings.


• Four tests were done in the single storey units across:

- A retained brick wall with a section of concrete blockwork infill, between units 8 and 9.

- A retained half brick wall with new independent wall lining between units 5 and 6.

- A new studwork wall, nominally 300mm thick, between units 5 and 6.

- A new studwork wall, nominally 300mm thick and with an atypical internal wall junction between units 6 and 7.

• One test was done in the two storey Victorian building across the extended brick/concrete blockwork separating wall at first floor level between units 2 and 1.

• Tests were done in accordance with BSEN ISO 140-4:1998. The relative location of the rooms tested are shown in Figures 2a and 2b. The results are tabulated below.

Source Room Receiving Room Element Tested DnT,w + Ctr

dB

Limit

dB - min

Lounge/bedroom (7)

Kitchen (6)

Lounge (5)

Lounge/bedroom (6)

Bedroom (2)

Bedroom (9)

Bedroom (5)

Bedroom (6)

Bedroom (7)

Bedroom (1)

Brick wall + infill

Half Brick wall + independent lining

Studwork wall

Studwork wall

Brick/Blockwork wall

47

52

52

48

48

43

43

43

43

43

42

The measured sound insulation met the requirements of the new Regulations

• The measured sound insulation of all the separating walls met the requirements of the new Regulations.

• The sound insulation of the solid brick and blockwork walls was 47 and 48dB (DnT,w + Ctr).

• The continuous studwork wall had a higher performance of 52dB (DnT,w + Ctr). Between Units 6 and 7 the sound insulation was lower at 48dB (DnT,w + Ctr). The reason for this was not investigated. However, a possible explanation is that between Units 5 and 6 the wall is continuous well beyond the common area separating the rooms tested. Therefore, there are no junctions with other walls where the sealing could reduce the sound insulation, and no flanking walls, such as an external wall, to transmit additional sound. Normally, there would be at least one junction with an external wall, so the lower result may be more typical.

• The results were comfortably above the limit. However, the design and the high standard of build that could be seen on site, indicated that great care had been taken to minimise flanking noise transmission, and so maximise the potential sound insulation of the separating walls. This might not always be the case in other developments. Furthermore, on each development each construction must pass every time it is tested. It would be unwise to assume that the separating walls built here could necessarily be downgraded and still achieve the sound insulation required.

Costs

• The cost of the construction has been estimated. This includes those constructions affected by the requirements of Part E, that is separating walls, internal walls, internal floors and ceilings. It does not include doors, surface finishes, floor coverings, fittings and fixtures.

• The cost is the total cost of installing these items including a proportion (15%) of site facilities overheads and profit but excluding VAT.

• Because each dwelling is different, the costs have been estimated for one pair of dwellings (Units 5/6) in the newer building and one pair of dwellings (Units 1/2) in the Victorian building.

• The rounded totals are £13,500 and £10,000. The main items are listed below.

• Units 5/6

- Separating Wall – (12m, combination of new stud wall and new independent wall lining): £4,050

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- New Internal Walls (10m) : £2,300

- New Ceiling (143m2): £7,250

1 Units 1/2

- Separating Wall (extension of existing wall): £1,500

- Internal floor: £4,450

- New Ceiling (over first floor): £3,900

• The new concrete ground floor was not essential for achieving adequate sound insulation and was installed for other reasons. However, it did mean that measures were not necessary to prevent sound flanking under studwork separating walls. The estimated cost of installing this floor in Units 5/6 but not removing the existing floor which had to be done in any case, was £6,250

• These costs are for all the works described, not the additional cost of complying with the latest revision of Part E.

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Case History 3: Conversion of Mid-Terrace Dwelling House/Shop into Flats


• The use of independent wall linings to limit flanking sound travelling vertically between flats in the staircase walls.

• The need to provide adequate sound insulation between the converted flats and the terraced houses on either side, even though these were not being redeveloped. If possible the sound insulation achieved should be tested on completion.

Existing Building

• The frontage of the terrace of houses is shown in Photograph 3.1.

Photograph 3.1 – Frontage of Terraced Houses

• The house had four floors of residential accommodation above a ground floor shop and basement. It has been used recently as a house of multiple

45

occupation. Figure 3.1 shows typical floor plans of the existing building. The central stairs continued up the building, higher floors having the same layout as the first floor.

Lounge

Bed 1

Lobby Bathroom

Kitchen

Bed 2

First Floor

Up

Up

Shop

StoreW C

Store

Void

MetersUp

Ground Floor Figure 3.1 – Existing Ground and First Floor Plans

• The house construction comprised:

• Solid brick external walls (340mm and 225mm) rendered on the outside and with sash windows.

• A part flat, part pitched tiled roof with parapet wall. The top storey built into the roof with dormer widows.

• Solid brick party walls, 225mm thick plus plaster finish.

• Internal brick walls, generally 110mm thick plus plaster finish.

• Brick fireplace and chimneybreast on one party wall.

• Some studwork internal partitions and wall linings faced with plasterboard on plaster on lath.

• Timber joist floor with floorboards or chipboard deck and plasterboard ceilings.

46

• Between the ground floor shop and first floor accommodation, there was a floated chipboard deck on top of older floor boarding.

• An internal staircase gave access to the first floor and above from the rear entrance.

• The ground floor and basement shop had direct access from the front of the building.

Measured Sound Insulation before Conversion

• Sound insulation tests were done on four existing floors and one staircase wall.

• Tests were done in accordance with BS EN ISO 140-4:1998 and BS EN ISO 140-7:1998. The results are tabulated below.

Source Room Receiving Room Element Tested DnT,w + Ctrr

dB

L’nT,w

1F Lounge

2F Lounge

3F Bedroom

3F Bedroom

Staircase

Ground floor Shop

1F Lounge

2F Bedroom

2F Kitchen

3F Bedroom

Timber Floor

Timber Floor

Timber Floor

Timber Floor

Brick Wall/Lobbied Door

43

38

39

38

37

62

67

73

72

-


• The building has been redeveloped as five flats. The ground floor and basement shop has become a two storey flat with its own entrance in the front façade. Each of the other four floors comprises one flat with a common staircase and entrance hall with access from the street at the back of the terrace.

• The layouts of the first floor flat, which is typical, and the ground floor are shown in Figure 3.2.

• Floorboards were made good, mineral wool quilt fixed between joists and joints sealed. The chipboard floating floor on the first floor had been damaged and was removed.

• Existing ceilings were upgraded and an additional plasterboard mf ceiling suspended below using proprietary acoustic hangers.

• The existing separating walls were 225mm solid brick with plaster finish and were expected to meet the performance standard without upgrading.

47

• Internal brick walls were kept.

• Internal stud walls and linings were all removed and replaced with new.

• Some doorways were filled in and other openings created in internal walls.

• Fireplaces were removed and chimney-breasts closed off.

Figure 3.2 - Layout of the Ground and First Floor Flat

Design Separating Floor Construction

• The existing floors did not give adequate sound insulation. Between the ground and first floor one test did just meet the sound insulation requirement for conversions, but the floating floor there was damaged and had to be removed.

• A suspended ceiling system was used. This improved the airborne and impact sound transmission. The construction is shown in Figure 3.3.

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• The existing ceiling was kept but upgraded where necessary to 20 kg/m2 with fire rated plasterboard and plaster skim finish.

• A new additional ceiling of 12.5mm + 15mm fire rated plasterboard (9.5 + 11.5 kg/m2) with plaster skim finish was suspended 150mm below the existing ceiling. It was fixed to an MF grid supported from the existing joists via acoustic hangers.

• The existing floorboards and chipboard were removed and 100mm of mineral wool quilt fixed between the 195mm deep joists.

• Refurbished or new floorboards were replaced and joints sealed with mastic.

Figure 3.3 - Section through Separating Floor

25mm floor boards - reused


Existing plasterboard + new 15mmfire rated plasterboard or existing 25mm lath and plaster

Acoustic Hanger

Strap hanger and MF grid

12.5mm + 15mm fire ratedplasterboard (21kg/m2 total)

Separating Walls

• Existing separating walls between this property and adjacent buildings in the terrace were kept unaltered. These were a minimum of 225mm solid brick plus plaster finish. Any unsound plaster was hacked off and replaced. It was considered that sound travelling down these walls between flats would be adequately attenuated.

Internal Walls

• Many of the internal walls were removed and replaced with plasterboard on timber studwork. The construction, shown in Figure 3.4, comprised 75 x 50mm timber studs at 600mm centres with 12.5mm dense plasterboard (10 kg/m2) each side and 80mm mineral wool quilt (10 kg/m3) in the cavity. This construction had an Rw of 41dB and meets the requirements in the

49

Regulations for new internal walls around bedrooms and rooms containing a water closet.

• Where an existing wall is retained the requirement for a 40dB Rw rating does not apply. However, the 225mm brick wall that was kept between the lounge and bathroom would meet the sound insulation rating.

Figure 3.4 - New Internal Wall

Acoustic sealant

1 x 12.5mm of plasterboard (10kg/m2)


75 x 50mm timber studs(600mm centres)

External Walls

• The external walls were 225mm and 340mm thick. These are heavy and it was not considered necessary to do anything further to reduce flanking sound transmission up and down them. The walls were lined inside the rooms with plasterboard faced 60mm thermal insulating board. To minimise flanking sound transmission, it would be more effective to use thermal board comprising plasterboard laminated with mineral wool, rather than with foamed plastic.

• It is important to check the weight of the inner leaf of external walls or other walls that are continuous between floor levels. Particularly with timber separating floors, lightweight blockwork will carry excessive flanking sound between flats and a plasterboard lining spaced well away from the wall is necessary.

• When the floorboards were replaced the junction between boards and inner leaf of external wall was sealed with acoustic sealant. Similar sealing was applied where the new suspended ceiling met the external wall lining and where ceiling and floors met the separating walls.

• A section of this junction is shown on Figure 3.5.

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Figure 3.5 - Section through Separating Floor/External Wall Junction

External Wall

60mm thermal board

Floor boards

Acoustic sealant

Mineral woolpacking

Separating Walls between Flats and Common Areas

• The walls separating flats and the common staircase and entrance hallway are retained brick walls or in one location new 100mm dense blockwork. Most of the brickwork walls around the staircase are only half brick, nominally 110mm plus plaster. These would not give adequate sound insulation between the flats and the staircase.

• The staircase walls might also be expected to carry sound vertically between flats bypassing the separating floors.

• These walls were upgraded by installing an independent plasterboard wall lining on their roomside.

• The lining comprised 2 layers of 12.5mm standard plasterboard (2 x 8 kg/m2) fixed to 75 x 50mm timber stud framework. The timber studs were spaced 50mm from the wall and 80mm of mineral fibre quilt hung between them. The construction is shown in Figure 3.6.

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Figure 6 - Lining to Upgrade Retained Brick Wall between Flats and Common Areas

2 x 12.5mm standard

75 x 50 mm

Acoustic sealant

Retained PlasteredHalf Brick Wall

80mm mineralwool (10kg/m3)

timber studs

plasterboard (2 x 8kg/m2)

Plaster

Doors

• The guidance in Approved Document E is that doors to common areas should have a mass of at least 25 kg/m2 and have good perimeter sealing all round. Solid timber doors were used. Entrances to apartments had a small lobbied hallway that protected the other rooms from noise intrusion.

• The two storey flat has a door from the kitchen out into the common hallway. The door was provided with acoustic seals.

Internal Floors

• There are internal floors between the ground floor and basement level of the two storey dwelling. If they had been new they would have had to have the sound insulation rating (40dB Rw). However, the existing floors were kept so no upgrading was required.

Common Areas

• Under the Regulations (Requirement E3), sound absorbing finishes must be installed in the common areas, in this building the hallway and staircase leading to the first floor flats and above. More details about these requirements, together with an example of the type of calculation that could be used, are given in Appendix 2.

• A suspended mineral fibre tile ceiling was used throughout the hallway to meet the requirement.

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• For the staircases the absorption was achieved by carpet throughout the staircase which was rated Class D and a suspended mineral fibre tile ceiling to the ceiling over the top floor which was Class C. This gave an adequate area of absorbing finish.

Services

• Ventilation fans were installed in or ducted directly to external walls and did not affect the sound insulation.

• Most soil vent pipes followed the existing route outside of the building. One soil vent pipe was taken between floors inside the building together with water pipes.

• The pipes that penetrated separating floors were boxed in the corner of the room to prevent them degrading sound insulation. The two sided enclosure ran between floor and the upper (not suspended) ceiling level. It comprised two layers of 12.5mm plasterboard (2 x 8 kg/m2) on timber grounds. The enclosure was divided inside into separate compartments for the SVP and the water pipes. The pipes were wrapped with 25mm of mineral wool quilt (10 kg/m3).

• The penetration within the depth of the separating floor was also treated with an intumescent collar and mineral fibre packing to provide adequate fire resistance. This also helped the sound insulation.

• The gas riser had the same enclosure construction but without the mineral wool wrapping which is not allowable under fire safety Regulations. The enclosure was also vented to outside at top and bottom at each floor level.


• The four new construction details, Figures 3.3 to Figure 3.6, were reviewed in light of the Building Regulations Part L1 and Part F.

• The improvements to the separating floors and walls (Figures 3.3, 3.4 and 3.6) will not affect the performance from a heat loss point of view. The insulation of external wall (Figure 3.5) may not meet the thermal insulation requirements unless the thickness of the thermal insulating board is 60 mm with the 225mm thickness solid brick wall.

• More details on the insulating material were required. The system was using Gyproc ThermaLine SUPER board. Data taken from the Gyproc White Book technical data series allows the U- values to be calculated. The external wall needs to reach a U- value of 0.35 W/m2 K to meet the minimum standards in Part L1 (2002), the following list gives the 4 combinations of U- values for the wall.

340 mm solid brickwork with 50 mm ThermaLine = 0.348 W/m2 K 340 mm solid brickwork with 60 mm ThermaLine = 0.293 W/m2 K 225 mm solid brickwork with 50 mm ThermaLine = 0.367 W/m2 K

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225 mm solid brickwork with 60 mm ThermaLine = 0.3407W/m2 K

• The U-values were calculated using the following inside and external surface resistances for a wall with horizontal heat flow taken from BS EN ISO 6946. (Rse of 0.04 m2K/W and Rsi of 0.13 m2K/W)

• The 225mm solid brickwork external wall must therefore use a 60 mm ThermaLine SUPER board to meet the Part L1 requirements.

• There is also a thermal bridge where the internal floor junction abuts the solid external wall. This was improved with extra mineral wool packing. An alternative would have been rigid phenolic foam against the timber joist, but the mineral wool is probably better from the acoustic point of view.

• The insulation of the walls for acoustic reasons helps with the conservation of fuel and power by improving the thermal performance of the building envelope. The overall air infiltration within the flats will be reduced because of the acoustic sealing and will make an improvement in internal comfort conditions. None of the improvements interfere with the purpose made ventilation paths and therefore do not affect Part F of the Building Regulations.



• Before the building was handed over and occupied a set of sound insulation tests were done between two pairs of rooms. Note that if different separating floor constructions had been used at different levels, a set of tests would have been required for each type of construction.

• Access could not be obtained to the largely unoccupied properties on either side, so the separating walls could not be tested. As the existing separating walls were 225mm solid brick with plastic finish, they were expected to meet the performance standard without upgrading. If the separating walls had been of a lighter construction, upgrading would have been necessary, probably by installing wall linings. This treatment would be required, even if the separating walls could not be tested because there was no access.



• Airborne and impact sound insulation of separating floors were measured between lounges and between a bedroom and kitchen. Carpets had been fitted so these were taken up about 75 percent for the tests. To comply with

54

the Regulations, impact tests cannot be done with carpet or other soft covering fitted except for heavy concrete floors (> 365 kg/m2) where it is a fixed part of the construction.

• The results are tabulated below.


dB

Limit

dB - min

1st Floor Lounge

1st Floor Bedroom

Staircase

Ground floor Lounge

Ground Floor Kitchen

1st Floor Bedroom

Separating Floor

Separating Floor

Separating Wall to Common Areas

54

51

47

43

43

43


1st Floor Lounge

1st Floor Bedroom

Ground Floor Lounge

Ground Floor Kitchen

Separating Floor

Separating Floor

50

58

64

64

The Measured Sound Insulation Met the Requirements of the New Regulations

• The airborne sound insulation of floors is well above the limit for conversions. It is important to note that this good performance relied on the flanking sound being well controlled. Half brick walls (110mm) that were continuous between floors were independently lined. Also all gaps between floorboards were sealed.

• The impact sound insulation was within the limit. It was significantly better between lounges than bedroom to kitchen. There was no apparent reason for this, although the fact that the kitchen is larger than the bedroom does explain 2dB of the difference.

• This shows that builders must allow a good margin in the design of separating floors for adequate sound insulation.

• The sound insulation between stairwell and flats would not be tested to show Building Regulations compliance because the accuracy of such measurements is less than those taken between rooms. However, for research purposes, a test was done between the stairwell and first floor bedroom. This showed that independently lining the half brick wall and having lobbied entrances achieved the sound insulation required in the design.

Costs

• The cost of the constructions has been estimated. This includes those constructions affected by the requirements of Part E, that is separating floors, new internal walls and linings, pipework enclosure and sound absorption in the hallway. It does not include doors, surface finishes, floor coverings (carpet), fittings and fixtures.

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• The cost is the total cost of installing these items including a proportion of site facilities overheads and profit but excluding VAT. It has been calculated for the first floor flat, which is typical, but excluding the separate utility room. The total area costed is 47m2.

• The rounded total is £6,400 for the typical flat plus £35/m2 for absorptive treatment to the hallway. The main items are:

Separating Floor: £5,000 Internal Wall : £400 Internal Wall Linings: £850 Boxing of SVP/Water Pipes: £160

• These costs are for all the works as described, not the additional cost of complying with the latest revision of Part E.

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Case History 4: Conversion of Detached Dwelling House to Flats and Bedsits


• Two types of upgrading to the timber separating floors. One a proprietary system using resilient elements and the other installing an additional suspended ceiling.

• Independent wall lining to existing walls both masonry and stud frame to improve direct sound insulation of wall and control flanking sound transmission.

Existing Building

• The front façade of the detached house is shown in Photograph 4.1.

Photograph 4.1 – The front façade of the detached House

57

• The house is on three floors plus a basement. The second floor extends over only part of the building. Recently the house had been used for multiple occupancy with shared facilities. Figure 4.1 shows ground and first floor plans of the existing building.

Figure 4.1 – Ground and First Floor Plans of Existing Building

• The house construction comprised:

• 340mm solid brick walls to the full height of the building with sash windows.

• A pitched tiled roof, with some small areas of flat roof.

• Internal walls of both brick and timber stud partitions. Brick walls were a mixture of half, single and one and a half brick thick.

• A central timber staircase.

• Brick fireplace and chimneybreast in internal walls.

• Timber joist floor with floorboards and a proprietary floating floor comprising chipboard on a fibrous board.

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• Lath and plaster ceilings and some plasterboard ceilings.

• Main pipework penetrations of walls and floors, generally boxed in.


• The building has been redeveloped as four flats and two bedsits. There are three on the ground floor, two on the first floor and one on the second floor. The basement will be used as offices/storage for support staff and a communal lounge.

• Layouts of the ground floor, first floor and basement after conversion are shown as Figures 4.2a 4.2b, and 4.2c.

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Figure 4.2a

60

Figure 4.2b

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Figure 4.2c

• All existing floating floors were removed, as were the floorboards at ground floor level. At higher floors the boards were refurbished or replaced where necessary.

• Between basement and ground floor a proprietary resilient floor system was installed on the existing joists. The existing ceiling was removed and a new plasterboard ceiling suspended via resilient bars.

• Between ground, first and second floors, the existing ceiling was kept and an additional plasterboard ceiling suspended below on an MF system.

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• Internal brick walls were kept.

• Some doorways were filled in and some new openings created in internal walls.

• The internal stud wall to one side of the central staircase was kept and an independent wall lining added.

• Other internal stud walls were removed and replaced with new.

• Fireplaces had already been removed and closed off.

Design

Separating Floor Construction

• Between the basement and ground floor the existing boarding, floating floor and ceiling were all removed. A new proprietary isolated floor, referred to as Type B, was installed comprising:

• Metal channels laid over the existing joists with resilient strips in between.

• 19mm plasterboard plank (15 kg/m2) between the joists, resting on the channels.

• 22mm boarding laid over and fixed to the channels, but not to the joists.

• A ceiling of 12.5mm dense plasterboard (10.5 kg/m2) + 19mm plasterboard plank fixed to the underside of the joists via resilient bar and with skim finish.

• 100mm thick mineral wool quilt (10 kg/m3) between the joists.

• This construction is shown in Figure 4.3. The resilient strips supporting the channels and the resilient bars supporting the ceiling are important to achieve impact sound isolation. It is essential that the floor boarding is not fixed through to the joists.

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Figure 4.3 - Separating Floor Construction between Ground Floor and Basement

Proprietary metal channel on resilient strip

22mm timber boarding

19mm plasterboard plank(15kg/m2)

Resilient bar19mm plasterboard plank

12.5mm dense plasterboard(10.5kg/m2) + plaster skim

(15kg/m2)

• Between the ground, first and second floors the existing floorboards were refurbished and replaced with 100mm of mineral wool quilt (10 kg/m3) between the joists.

• The existing plaster ceilings were kept if possible, but where damaged were replaced with 2 layers of 12.5mm plasterboard (16 kg/m2).

• An additional ceiling of 1 layer of 12.5mm dense plasterboard (10.5 kg/m2) was suspended on an MF system 200mm below the existing ceiling. 100mm of mineral wool quilt (10 kg/m3) was laid on this ceiling.

• In this second floor construction, referred to as Type A, the isolation of impact sound depends on the resilience inherent in the metal furring suspension system. This construction is shown in Figure 4.4.

Figure 4.4 - Separating Floor Construction between Second, First and Ground Floors

Timber floor boards

100mm mineral wool quilt(10kg/m3)

2 x 12.5mm plasterboard(2 x 8.0kg/m2)

100mm mineral wool quilt(10kg/m3)

12.5mm plasterboard(10.5kg/m2)

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Separating Walls

• Separating walls between dwellings are all existing plastered brick walls and with one exception at least 340mm thick. It was considered that sound travelling between flats both directly through and indirectly down or along these walls would be adequately attenuated.

• Where existing doorways were closed off, they were blocked in with a matching thickness of brickwork tied into the existing wall and plastered

• On the ground and first floor there was one short length of half brick wall which formed part of a new separating wall between bathroom/shower room/kitchen. This was given an independent plasterboard lining on 75 x 50mm timber studs or 70mm metal I-studs. The stud frame was spaced at least 50mm from the existing wall.

• The lining which was applied both sides of the wall controlled transfer up and down the wall as well as through it. On one side the lining comprised 2 layers of 12.5mm plasterboard (2 x 9.5 kg/m2) on I-studs with 75mm mineral fibre slab (24 kg/m3) between the studs. On the other side the cavity was larger (>100mm) and only 1 layer of the plasterboard (9.5 kg/m2) was used on timber studs. 80mm of mineral wool quilt (10 kg/m3) was suspended in the cavity between the studs.

• The construction of the wall lining is shown in Figure 4.5.

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Figure 4.5 - Wall Lining to Masonry Walls

Existing 110mm brickwall + plaster

75mm mineral fibre

12.5mm plasterboard9.5kg/m2

80mm mineral woolquilt (10kg/m3)

2 x 12.5mm plasterboard (2 x 9.5kg/m2) + skimon 70mm metal studs

(24kg/m3)

Internal Walls

• Where existing walls are retained, there is no sound insulation requirement under Part E of the Building Regulations. The walls kept as internal walls were all of brick work.

• New internal walls comprised 12.5mm dense plasterboard (10.5 kg/m2) each side of 100mm timber studs with 100mm mineral wool in the cavity as shown in Figure 4.6. This complied with the acceptable internal wall constructions given in Section 5 of Approved Document E 2003.

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Figure 4.6 - New Internal Walls

100 x 50mm timber studs


12.5mm dense plasterboard (10.5kg/m2)

External Walls

• The external walls were 340mm solid brickwork. These are very heavy, and it was not considered necessary to do anything to reduce flanking sound transmission up and down or along them. The walls were lined inside the rooms with 50mm thick thermal laminated board.

• The perimeters of all ceilings, including with the external wall were sealed with flexible acoustic sealant.

• A section of this junction is shown in Figure 4.7.

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Figure 4.7 - Junction Separating Floor and External Wall

Acoustic Sealant

Existing External Wall340mm brickwork + plaster

50mm Thermal Board

Mineral woolpacking

Timberwall plate

Separating Walls between Flats and Common Areas

• The walls between flats and common hallways are 250mm and 360mm plastered solid brickwork. These provide adequate sound insulation.

• One of the existing walls between flats and the staircase was 110m brickwork and at first floor level and above it changed to a timber stud partition comprising a single layer of 12.5mm plasterboard each side of 100mm timber studs with 25mm of mineral wool quilt in the cavity.

• An independent plasterboard wall lining was added to the whole wall. This comprised 2 layers of 12.5mm fire rated plasterboard (2 x 9.5 kg/m2) and skim fixed to 70mm deep metal I-studs and with 75mm of fibre slab (24 kg/m3) fixed between studs.

• The existing staircase wall was also uprated by adding a second layer of the 12.5mm plasterboard to the other side.

• A section through the new construction is shown in Figure 4.8.

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Figure 4.8 - Separating Wall Construction between Staircase and Flats (Horizontal Section)

75mm mineral fibre

12.5mm plasterboard9.5kg/m2

Existing Partition

Additional layer of2 x 12.5mm plasterboard (2 x 9.5kg/m2) + skimon 70mm metal studs

(24kg/m3)

Doors

• The guidance in Approved Document E is that doors to common areas should have a mass of at least 25 kg/m2 and have a good perimeter sealing. 44mm solid timber doors were used.

• Three of the flats have a small hallway which acts as a lobby between the common hallway/stairs and the other rooms protecting them from noise intrusion. The other flat and the two bedsits are provided with a small entrance lobby.

Common Areas

• Under the Regulations, sound absorbing finishes must be applied in the common areas. More details about these requirements, together with an example of the type of calculation that could be used, are given in Appendix 2.

• A suspended mineral fibre tile ceiling was used throughout the hallway to meet this requirement.

• For the staircase adequate absorption was achieved by carpet throughout the staircase which was rated Class D and a suspended mineral fibre tile ceiling

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to the ceiling over the top floor which was Class C. This was an adequate area of absorbing finish.

Services

• Ventilation fans were installed in or ducted directly to external walls and did not affect the sound insulation.

• Soil vent pipes, water and gas pipes ran inside the building through the separating floors in the corners of several rooms. They were boxed into prevent them degrading the sound insulation. The two sided enclosure ran between floor and the upper ceiling level. It comprised two layers of 12.5mm plasterboard (2 x 9.5 kg/m2) on timber grounds. 80mm thick mineral wool quilt (10 kg/m3) was hung and packed in around the four sides of the enclosure.

• The penetration within the depth of the separating floor was also treated with an intumescent collar and mineral fibre fire stopping to provide adequate fire resistance. This also helped the sound insulation.

• Risers containing gas pipes were treated the same way except that to comply with Fire Safety Regulations the quilt was omitted and the riser was vented top and bottom at each floor level through the external wall.


• The six new construction details, Figures 4.3 to Figure 4.8, were reviewed in light of the Building Regulations Part L1 and Part F.

• The improvements to the separating floors and walls (Figures 4.3,4.4,4.5,4.6 and 4.8) have internal conditions and will not affect the performance from a Heat loss point of view. The insulation of external wall (Figure 4.7) meets the thermal insulation requirement with 50 mm ThermaLine SUPER board.

• More details on the insulating material were required. The system was using Gyproc ThermaLine SUPER board. Data taken from the Gyproc White Book technical data series allows the U- values to be calculated. The external wall needs to reach a U- value of 0.35 W/m2 K to meet the minimum standards in Part L1.

340 mm solid brickwork with 50 mm ThermaLine = 0.348 W/m2 K 340 mm solid brickwork with 60 mm ThermaLine = 0.293 W/m2 K

• The U-values were calculated using the following inside and external surface resistances for a wall with horizontal heat flow taken from BS EN ISO 6946. (Rse of 0.04 m2K/W and Rsi of 0.13 m2K/W) The 50 mm thickness is just able to meet the minimum standard.

• There is also a thermal bridge where the internal floor junction abuts the solid external wall. This was improved by packing mineral wool against the timber

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wall plate. As an alternative solid phenolic foam could have been used, but mineral wool is probably better for acoustic reasons.

• The insulation of the walls for acoustic reasons helps with the conservation of fuel and power by improving the thermal performance of the building envelope. The overall air infiltration within the flats will be reduced because of the acoustic sealing and will make an improvement in internal comfort conditions. None of the improvements interfere with the purpose made ventilation paths and therefore do not affect Part F of the Building Regulations.



• Before the building was handed over and occupied, sound insulation tests of the floors were done. Since a different construction had been used for the ground floor, a set of tests was done for each type, that is between first and ground, and between ground and basement.

• As the basement is not a dwelling, although part of the same building, it was only necessary under the Building Regulations to do airborne tests across this floor. However, impact tests were also done to gain information that may be useful when applied to other developments.



• Airborne and impact sound insulation of separating floors were measured between living rooms/bedsits/bedrooms on the ground and first floor. In the basement the office and communal lounge were used. So that the impact tests complied with the guidance, the testing was done before carpets had been fitted. Otherwise the construction was complete except that the threshold seals to entrance doors had not yet been fitted.

• The results are tabulated below.


dB

Limit

dB - min

1st Floor Bedsit Ground Floor Living Room

Separating Floor Type A

45 43

Ground Floor Living/Kitchen

1st Floor Living Room Separating Floor Type A

53 43

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Basement Office Ground Floor Bedsit Separating Floor Type B

51 43

Basement Lounge Ground Floor Living/Kitchen

Separating Floor Type B

50 43

1st Floor Bedroom 1 Ground Floor Bedroom 1


51 43


1st Floor Bedsit Ground Floor Living Room


49 64

1st Floor Living Room Ground Floor Living/Kitchen


53 64

Ground Floor Bedsit Basement Office Separating Floor Type B

49 64

Ground Floor Living/Kitchen

Basement Lounge Separating Floor Type B

52 64

1st Floor Bedroom 1 Ground Floor Bedroom 1


49 64

The measured sound insulation met the requirements of the new regulations

• The airborne sound insulation of both types of floor is above the limit for conversions. The results for the first floors (Type A) vary significantly. This construction has potentially high sound insulation which is usually reduced on site by flanking transmission. The sound insulation achieved depends on the degree of flanking. Here the flanking appeared to relate to the amount of kitchen equipment, service penetrations, and weight of flank walls.

• The variation noted above shows that for conversions builders must treat flanking transmission thoroughly and allow a good margin in a basic separating floor or wall design.

• The impact sound insulation was well within the limit for both floor types.

• To show Building Regulation compliance the existing 340mm brick wall construction, kept as separating walls, was also tested and passed comfortably (DnT,w + Ctr = 54dB).

• The sound insulation between stairwell and flats would not be tested to show Building Regulations compliance because the accuracy of such measurements is less than those taken between rooms. However, for research purposes, it was measured here for Bedroom 1 on the first floor. It was marginally below the standard (DnT,w + Ctr = 42dB), with a weakness at mid to high frequency. It appeared to be due to leakage under the entrance doors where the threshold seal and carpet had not yet been fitted and this will be rectified. The basic design of the wall construction itself is adequate.

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Costs

• The cost of the constructions has been estimated. This includes those constructions affected by the requirements of Part E, that is separating floors, separating staircase wall lining pipework enclosure and sound absorption in the hallway. It does not include doors, doorways, surface finishes, floor coverings (carpets), fittings and fixtures.

• The cost is the total cost of installing both the separating floor types including a proportion of site facilities overheads and profit but excluding VAT.

• The examples chosen for costing are:

• The first floor bedsit floor (above ground floor living room/kitchen/shower room)

• The ground floor bedsit floor (above basement office)

• The staircase wall lining at first floor level (to bedroom 1).

• The costs for the floors can be applied to bedsit of similar area (28/24m2).

• The costs for each item are as follows:

Separating floor (between first and ground floors): £3,200

Separating floor (between ground floor and basement): £2,700

Wall lining (first floor level): £700

SVP/water pipe boxing/per enclosure:£135

• These costs are for all the works as described, not the additional cost of complying with the latest revision of Part E.

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Appendix 1

• The insulation of lightweight constructions against airborne sound can be rated in terms of a laboratory measurement (Rw + Ctr) in decibels (dB). The Regulations stipulate that the acoustic performance standard for separating walls should be (DnT,w + Ctr) of at least 43dB. This is the value measured on site. Catalogues of proprietary systems show their acoustic performance differently; as (Rw + Ctr) which has been measured in a laboratory. The designer has to allow for the differences in these which depend upon room geometry, flanking and quality of finish.

.

• As a rough rule of thumb for a lightweight structure at least 7dB should be subtracted from the laboratory measured (i.e. catalogue) value to allow for these factors. More should be subtracted if the room dimensions perpendicular to the separating wall or floor (called the depth) are small (see table below) or if there is any reason to suspect workmanship or excessive flanking.

Smaller depth of the two m

Subtract from laboratory (catalogue) value

dB

2 9

2.5 8

3 7

4 6

5 5

6 4

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Appendix 2

• Under the Regulations (Requirement E3), sound absorbing finishes must be installed in the common areas which give access to the flats. This normally means that absorbent treatment need only be applied to those common areas onto which dwellings open direct. The guidance in Section7 of Approved Document E describes how to calculate the area of such finishes required.

• One option for entrance halls, hallways and corridors is to install an area of Class C (or better) sound absorbing finish equal to the floor (or ceiling) area. ‘Class C’ is a rating based on the sound absorption coefficients of the finish as measured in a laboratory.

• For staircases the area calculation is different. It is the combined area of stair-treads, upper surfaces of intermediate landings and landings (excluding the lowest floor) and the ceiling area of the top floor. An area of Class D sound absorbing finish equal to or greater than this calculated area is required. Alternatively, half the area of Class C absorber is adequate.

• There may be some sound absorbing finishes already in the common areas. These may not be adequate to meet the requirements described above. For entrance halls, hallways and corridors, the Regulations allow this absorption to be taken into account and only a reduced amount of new sound absorbing finish needs to be added. In such cases a calculation must be done to show that the amount of absorption across a range of frequencies meets criteria given in the Regulations. A similar calculation can be used where a number of smaller areas of different sound absorbing finishes are to be installed.

• An example of such a calculation is given below. This type of calculation cannot be used for staircases, for which the basic area calculation is the only option.

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Building Regulations Sound Absorption in Entrance Halls, Corridors and Hallways Example Calculation

DIMENSIONSLength (m) 14 Glazing (m2) 0Width (m) 1.2 Doors (m2) 10Height (m) 2.7 Wall Treatment (m2) 0Volume (m3) 45.36 Ceiling Treatment (m2) 8

Absorption Required (m2Sab) = 11.34 Absorption CoefficientsAbsorption (m2Sab)

Octave Band Centre Frequency - HzSurface Area Finish 250 500 1000 2000 4000

Floor 16.8 Carpet 0.03 0.06 0.15 0.30 0.400.50 1.01 2.52 5.04 6.72

Walls 72.1 Plasterboard Wall 0.15 0.10 0.05 0.05 0.0510.81 7.21 3.60 3.60 3.60

Wall Treatment 0 None 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00

Doors 10 Timber Door 0.10 0.08 0.08 0.08 0.081.00 0.80 0.80 0.80 0.80

Glazing 0 None 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00

Ceiling 8.8 Suspended Plasterboard Ceiling 0.15 0.10 0.05 0.05 0.051.32 0.88 0.44 0.44 0.44

Ceiling 8 Mineral fibre tile 0.20 0.30 0.55 0.55 0.45Treatment 1.60 2.40 4.40 4.40 3.60

Total Absorption (m2Sab) 15.24 12.30 11.76 14.28 15.16

Extra Absorption Required (m2Sab) None None None None None

Same Example Calculation with Notes Added

With Method B in section 7 of Approved Document E 2003,the aborption required depends on the volume of the room.The volume is calculated in m3 from the room dimensions.Sound absorption is expressed in m2Sabines ( often just m2 ) and the requirement is calculated as follows:For Entrance Halls the requirement = 0.2 x volume (m2Sab)For Corridors and Hallways the requirement = 0.25 x volume (m2Sab) Absorption Coefficients

Absorption (m2Sab)Octave Band Centre Frequency - Hz

Surface Area Finish 250 500 1000 2000 4000Absorption Coefficients from laboratory tests or ADE Table 7.1 Table 7.1 "Soft Floor Coverings"Floor 16.8 Carpet 0.03 0.06 0.15 0.30 0.40Absorption provided is calculated by 0.03x16.8 0.06x16.8 0.15x16.8 0.3x16.8 0.4x16.8multiplying the area of each surface finish by its absorption coefficient = 0.5 = 1.01 = 2.52 = 5.04 = 6.72Walls 72.1 Plasterboard Wall 0.15 0.10 0.05 0.05 0.05

10.81 7.21 3.60 3.60 3.60Wall Treatment 0 None 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00Doors 10 Timber Door 0.10 0.08 0.08 0.08 0.08

1.00 0.80 0.80 0.80 0.80Glazing 0 None 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00Ceiling 8.8 Suspended Plasterboard Ceiling 0.15 0.10 0.05 0.05 0.05

1.32 0.88 0.44 0.44 0.44Ceiling 8 Mineral fibre tile 0.20 0.30 0.55 0.55 0.45Treatment 1.60 2.40 4.40 4.40 3.60

Example sum of absorptions at 250 Hz 0.5+10.81+1+1.32+1.6 = 15.24Total Absorption (m2Sab) 15.24 12.30 11.76 14.28 15.16

Additional Absorption area required (m2Sab) None None None None None

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Appendix 3


• Between dwelling houses each set of tests comprises, where possible, two airborne sound insulation measurements across a separating wall between different pairs of rooms. The sound level difference measured (DnT,w + Ctr) must be at least 43dB in conversions: The noise level difference is affected by sound traveling via all transmission paths not just directly through the wall, so the control of flanking sound is important.

• Between flats each set of tests comprises, where possible:

• Where there are separating walls, two airborne wall sound insulation measurements as above

• Two airborne sound insulation measurements across a separating floor between different pairs of rooms. The DnT,w + Ctr must be at least 43dB in conversions.

• Two impact sound insulation measurements on a separating floor between two different pairs of rooms. The impact sound (L’nT,w) must be no greater than 64dB in conversions

• Note that more onerous limits apply to new build dwellings.

• Testing is not required between dwellings and common areas.

• On site testing is not required for internal walls or floors (that is between rooms in the same dwelling) although for new internal floors and certain walls there is a minimum laboratory airborne sound insulation rating required.

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Table A3.1 – Summary of Sound Insulation Achieved by Constructions Studied

Brief Description of Separating Construction (For full details see individual case histories)

Flanking Paths Before Treatment DnT,w + Ctr

dB

L’nT,w

dB

Limit in Part E for Conversions 43 min 64 max

Case History 1

Wall: 2 x 15mm dense p/b each side of 90mm metal studs, 75mm m/w in cavity

Floor: Timber deck on resilient battens, on upgraded timber joist floor/ceiling, additional suspended 12.5mm p/b ceiling on mf

Existing timber floor, continuous under walls. Heavy masonry walls

Service penetrations

Heavy masonry walls

44, 45

47, 52

54, 56

Case History 2

Wall A: Existing brick + dense cavity block infill

Wall B: Existing brick + 200mm dense block above

Wall C: Existing ½ brick + IWL (2 x 12.5mm dense p/b)

Wall D: 2 x 12.5mm dense p/b on independent timber stud frames + m/w

Flat roof

Existing/new roof structure

Flat roof

Flat roof, existing timber ground floor

47

48

52

48, 52

Case History 3

Floor: Upgraded timber joist floor/ceiling, additional 12.5 + 15mm p/b ceiling on mf and acoustic hangers

Wall to Staircase: Existing ½ brick, IWL (2 x 12.5mm p/b)

Existing ½ brick walls

(Test for research, not required by Regulations)

54, 51

47

50, 58

Case History 4

Floor A: Upgraded exiting timber joist floor/ceiling, additional 12.5mm dense p/b mf suspended ceiling

Floor B: Refurbished timber boards on resilient element, 19mm p/b + m/w between joists, 19 + 12.5mm dense p/b ceiling fixed via resilient bars

Existing ½ brick and studwork walls. Service penetrations

Service penetrations

45, 51, 53

51, 50

49, 49, 53

49, 52

Notes on Abbreviations in Table 3.1 p/b = plasterboard m/w = mineral wool IWL = independent wall lining mf = metal furring

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