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FLO

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SECTION 3

Contents

Floors

100

The chart below can be usedas both a contentslist and a trackingmechanism, as shown on page 18

Total Insulation Solutions

Whatever you need to insulate, KnaufAlcopor has the answer.We havesolutions for the thermal insulation, acoustic insulation and fireprotection for buildings, building services and industrial applications

As the UK’s largest manufacturer of insulation products, we can provideyou with the most appropriate glass mineral wool, rock mineral wool orextruded polystyrene product to meet your insulation requirements,backed up with the best all round service and support package.

Floatingchipboard deck

Page 109

Ground FloorsDesign ConsiderationsPage 102

FloorsProduct Selector Page 101

Insulationbelow slab

Page 105

Floatingscreed

Page 107

Upper FloorsDesign ConsiderationsPage 112

ThermalApplications

Suspendedtimber

Page 111

FireApplications

Floatingscreed

Page 113

Floatingchipboard deck

Page 114

Suspendedtimber

Page 115

Refurbishment ofseparating floor

Page 116

101

Product Selector

Floors

Tel 01744 693885 E-mail [email protected]

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Product

Belowconcrete

slab

Underfloatingscreed

Under floatingchipboard

deck

Timbersuspended

floor

Upgrading oftimber

suspendedfloor

p 107 p 109

p 106 p 108 p 110

p 111

Ground floors-thermal

Polyfoam º Floorboard • • •

Crown º Floor Slab • • •

Crown º Wool •Upper floors-thermal

Polyfoam º Floorboard • •

Crown º Wool •Upper floors-fire

Rocksil Slab RS33 •p 116

p 115

p 105

p 113 p 114

Thermal Insulation

Ground Floors – Design

GeneralThe two most important factors toconsider when insulating a ground floorare:

• What thickness of insulation will berequired to meet the BuildingRegulations?

• Where is the insulation to bepositioned within the floor structure?

Other design considerations includepreventing condensation, minimising airleakage, thermal bridging and the compressionresistance of the insulation.

Building RegulationRequirementsThe table shows the U-value requirementsin the Building Regulations for groundfloors.

Calculation of U-valuesUnlike walls and roofs, the heat lossthrough a ground floor varies with its sizeand shape.The Building Regulationsrequire that when ground floor U-valuesare calculated, BS EN ISO 13370: 1998should be used.As well as the groundfloor’s perimeter to area ratio, the BritishStandard also takes into account theinsulating effect of the external walls andthe sub space below suspended groundfloors.

The measurement of the perimeter andarea should be to the finished insidesurfaces of the perimeter walls thatenclose the heated space. Projecting baysshould be included, but unheated spacessuch as porches or garages should beexcluded.

In the case of semi-detached, terraceddwellings and blocks of flats the floor

The graphs assume the ground has athermal conductivity of 1.5 W/mK.The U-values for Crown Wool assume it isplaced between 50mm timber floor joistsspaced at 600mm centres.To calculate U-values to your own specificrequirements, KnaufAlcopor recommendthe use of its Architectural CalculationSuite (ACS) version 5.

The following worked example illustrateshow to use the graphs.

102

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8Ratio of perimeter (m) to area (m2)

0.35

0.30

0.20

0.10

U-v

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(W/m

2 K)

0.25

0.15

60mm80mm

100mm

150mm

200mm

0.35

0.30

0.20

0.10

U-v

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(W/m

2 K)

0.25

0.15


25mm 35mm50mm

75mm

100mm

Suspended timber ground floor U-values using Crown Wool

Building Regulation requirementsfor ground floors

U-value (W/m2K)

Dwellings Central heating with SEDBUK 0.25value from Table 2 (In Building Regulations)

Other heating systems (1) 0.22(Scotland only)

Buildings other than dwellings 0.25

Note (1) Other gas or oil central heating system, or an electric heating system or solid fuel central heating or undecided – this U-value is applicable only in Scotland.

U-values for solid ground floor using Polyfoam Floorboard


0.35

0.30

0.20

0.10

U-v

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(W/m

2 K)

0.25

0.15

25mm 35mm50mm

75mm

100mm

U-values for Beam and block ground floor with PolyfoamFloorboard insulation and chipboard finish

dimensions can either be taken as those ofthe individual dwellings themselves, or ofthe whole building.When consideringextensions to existing buildings the floordimensions may be taken as those of thecomplete building including the extension.

Determining the U-valueThe graphs below allow U-values to bedetermined for the range of KnaufAlcoporinsulation materials recommended forinsulating ground floors.

Example – a semi-detached houseas shown belowPerimeter P = 8+4+3+6+5 = 26m

Area A = (10x8)-(6x3) = 62m2

Ratio P/A = 26/62 = 0.42

Reading off from the graphs on the leftshows that a ground floor with a P/Aratio of 0.42 would achieve U-values of 0.25 W/m2K or better if insulated witheither 75mm Polyfoam Floorboard in aconcrete floor, or 150mm Crown Wool ina suspended timber ground floor.

Tel 01744 693885 E-mail [email protected] 103

Thermal Insulation


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Position of InsulationThe position of the insulation in a groundfloor influences the thermal mass of abuilding. Positioning the insulation under ascreed or chipboard/timber boarding willallow the building to heat up quicklybecause the insulation is close to theinside of the building.This is best suited tobuildings with intermittent heating systems.

Positioning the insulation below the slabincreases the thermal capacity of thebuilding.This results in more eventemperatures and a reduced risk ofcondensation.This is best suited tobuildings that are continuously heated orbenefit from significant solar gains.

In ground level suspended timber floorsabove a ventilated airspace the insulationis normally located between the joists.Timber floors have little thermal mass andare therefore best suited to intermittentheating systems.

The illustrations on the right show typical‘robust’ details

CondensationInsulating a solid or timber ground floorincreases the temperature differenceacross the construction, but thecondensation risk is minimal.

Floating screed on slip sheet

Insulation

Concrete slab

Damp proof membrane

Chipboard/timber boarding

Insulation

Beam and block floor

Insulation between joists

Chipboard/timber boarding

Polypropylene netting

Continue wall insulation at least150mm below top of floor insulationand support on a row of ties.

Ventilated airspace

Concrete slab

Insulation

Damp proof membrane

Screed

Continue wall insulation at least150mm below top of perimeterinsulation and support on a row ofties.

Continue wall insulation at least150mm below top of perimeterinsulation and support on a row ofties.

Continue wall insulation at least150mm below top of floor insulationand support on a row of ties.

Concrete floor with floating screed

Beam and block floor with floating chipboard deck

Suspended timber ground floor

Concrete ground floor with insulation under slab

Minimum 30mm mineral woolinsulation between last joist and wall

Thermal Insulation


104

Dead loads applied by various building componentsElement Dead load (kN/m2)

Flooring grade chipboard 0.1 to 0.2

65mm concrete screed 1.50

75mm concrete screed 1.75

150mm concrete floor slab 3.50

Additional design load to BS 6399: Part 1: 1996 (dwellings) 1.50

Avoiding air leakage in suspendedtimber ground floors

Bead of sealant

Expanding foamtape compressedwhen skirtingfixed

The applied load has two components:

• the dead load, which is due to theweight of the materials laid on theinsulant, and

• the design load.

BS 6399: Part 1: 1996 suggests that indwellings, a design load of 1.5 kN/m2

should be allowed for in all cases.

The dead loads applied by various buildingcomponents are shown in the table.TheApplications section shows thecompression resistance of individualinsulants, where relevant.

British StandardsDesigners should consult BS 5669: Part 2:1989 and BS 7916:1998 when selectingchipboard or other floor decking boards.

Guidance on the design and installation ofconcrete bases and screeds to receive in-situ flooring is given in BS 8204: Part 1:1999.

Advice on resilient floor coverings,including recommendations for suitablebases is given in BS 8203:1996.

A vapour barrier is not normally requiredfor most ground floor constructions.However, a vapour barrier should beinstalled between the insulation and achipboard floor, especially if there is a riskof excessive moisture from the floor slabdrying out.

Thermal BridgingThermal bridges are a significant source ofheat loss.They may also cause localisedcondensation and mould growth,depending on the change in temperaturelevels at these locations.

Correct detailing at the junction of thefloor slab and external wall, as shown inthe drawings on the previous page, willreduce thermal bridging and thus the riskof condensation.

Timber joists, and timber battenssupporting floor panels have a greater heatloss than thermal insulation materials.The U-value tables in the Applications sectionallow for thermal bridging by timbermembers, where relevant.

Air LeakageWith suspended timber ground floors,care is needed to minimise air leakagefrom the ventilated sub floor void into theheated space.As well as gluing the jointsbetween the floor deck panels, the floorperimeter should be sealed by applyingexpanded foam tape under the skirtingand a continuous bead of sealant to theback of the skirting prior to fixing.

Compressive StrengthAll materials are compressed under load.Insulation materials used in floors shouldbe capable of accommodating the appliedloads with the minimum of compression.

KnaufAlcopor recommend Polyfoam Floorboard for the thermalinsulation of solid ground floors with insulation below the slab.Crown Floor Slab can also be used in this application where amineral wool product is preferred.


Insulation Below Slab – Polyfoamº Floorboard

Ground Floors – Applications

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Polyfoam Floorboard is made from HCFC/CFC-free, 100% ozone friendly extrudedpolystyrene and formed into rigid boards.The boards are available in fourcompressive strengths:

• 220 kPa – domestic loading

• 350 and 500 kPa – high loads such asvehicle access, including fork lift trucks

• 700 kPa – high loads including rackingsystems.

Polyfoam Floorboard 500 is supplied withinterlocking rebated edges. PolyfoamFloorboard 220, 350 and 700 are suppliedwith square edges.

Typical ConstructionA solid concrete ground floor slab on adamp proof membrane on PolyfoamFloorboard insulation laid directly overblinded hardcore.A strip of insulation,minimum 25mm thick, should be placed

vertically at the slab perimeter tominimise thermal bridging.The concreteslab may be screeded or alternatively havea power float finish.

This construction is also suitablefor basements.

Typical SpecificationThe whole of the ground floor areabetween brick, block or concrete subwallsto be insulated with Polyfoam Floorboard220*/ 350*/ 500*/ 700*, (*delete asrequired), ….mm thick, and laid directlyover blinded hardcore.A strip ofperimeter insulation, minimum 25mmthick, to be placed vertically against thesubwalls tothe depth of the concrete slab.

The insulation to be overlaid with a dampproof membrane, which should lap theperimeter wall dpc. Concrete slab andfloor finish as specified by the designer.

Performance

Thermal performancePolyfoam Floorboard 220 and 700 have athermal conductivity of 0.028 W/mK.Polyfoam Floorboard 350 and 500 have athermal conductivity of 0.027 W/mK.

The table gives U-values for a range ofperimeter/area ratios. For an explanationof how to calculate ground floor U-values,see page 102.

Fire performanceThe boards will be contained within thefloor and therefore will not contribute tothe development stages of a fire orpresent a smoke or toxic hazard.

Moisture resistance The boards will not provide a watervapour controlling layer. However, theboards are resistant to water absorptionand can be laid in ground water or upagainst wet concrete without allowingmoisture to cross the finishedconstruction.

Compression resistanceThe boards are highly resistant tocompression and able to withstand long-term static loads.

BBA CertificationPolyfoam Floorboard 220, 350 and 500 arecertified by the BBA.

Installation The sand blinding should be level, withouthollows or undulations, to receive theinsulation boards. Polyfoam Floorboard islaid in a staggered pattern over the wholefloor area.The joints should be tightlybutted.The perimeter insulation boardsare cut to size and should be securely heldin place to prevent dislodgement byfollowing work.

The damp proof membrane is laid overthe insulation and laps with the wall dpc.When placing the concrete floor, spreaderboards should be used as necessary toprevent point loads puncturing the dpm.

Concrete ground slab


25mm Polyfoam Floorboard cut andplaced vertically at perimeter

Damp proof membrane

Polyfoam Floorboard

Sand blinding on hardcore

U-values (W/m2K) of concrete ground floor slab insulated with Polyfoam Floorboard 220

U-values (W/m2K)

Product Thickness Ratio of perimeter (m) to area (m2)

(mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

100 0.11 0.15 0.17 0.18 0.19 0.20 0.21

75 0.12 0.17 0.20 0.22 0.23 0.24 0.25

50 0.14 0.20 0.25 0.28 0.29 0.31 0.33

35 0.15 0.23 0.29 0.33 0.36 0.38 0.40

25 0.16 0.26 0.32 0.37 0.41 0.45 0.47

Note:The U-values have been calculated using BS EN ISO 13370: 1998 and assume a clay subsoil with athermal conductivity of 1.5 W/mK.

Polyfoam

Floorboard 220

Crown Floor Slab is a rigid, compressionresistant, glass mineral wool slab.

Typical ConstructionA solid concrete ground floor slab withCrown Floor Slab positioned on the dampproof membrane, laid over sand blindingon hardcore.A strip of insulation,minimum 25mm thick, should be placedvertically at the slab perimeter to minimisethermal bridging.The concrete slab may bescreeded or, alternatively have a powerfloat finish.

Building paper with lapped joints to be laidover the insulation. Concrete slab andfloor finish as specified by the designer.

Performance

Thermal performanceCrown Floor Slab has a thermalconductivity of 0.031 W/mK.


Fire performanceCrown Floor Slab is classified as Class 1surface spread of flame to BS 476: Part 7:1997 and Class 'O' to the BuildingRegulations.

Compressive strengthThe graph shows the compressionresistance curve for Crown Floor Slabunder progressive loading.The applied loadhas two components: the dead load whichis due to materials laid on to the insulant,and the design load. BS 6399: Part 1: 1996suggests that in dwellings, a design load of1.5 kN/m2 should be allowed for in allcases.

Installation The sand blinding should be level, withouthollows or undulations, to receive thedamp proof membrane. Lap the dpm withthe wall dpc. Crown Floor Slab is laid in astaggered pattern over the whole floorarea.The joints should be tightly butted.The perimeter insulation slabs are cut tosize and should be securely held in placeto prevent dislodgement by followingwork.

The whole of the insulation should becovered by building paper to prevent theloss of fines from the concrete.

When placing the concrete floor, spreaderboards should be used as necessary toprevent point loads puncturing the buildingpaper.

Insulation Below Slab – Crownº Floor Slab


KnaufAlcopor recommend Crown Floor Slab for the thermalinsulation of solid ground floors with insulation below the slabwhere a mineral wool product is preferred.

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100

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Applied load (kN/m2)

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25mm Crown Floor Slab cut and placedvertically at perimeter

Building paper

Crown Floor Slab

Damp proof membrane


U-values (W/m2K) of concrete ground floor slab insulated with Crown Floor Slab

U-values (W/m2K)


(mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Crown Floor Slab 50 0.14 0.21 0.26 0.29 0.32 0.33 0.35

40 0.15 0.23 0.28 0.32 0.35 0.38 0.39

25 0.17 0.26 0.33 0.39 0.43 0.47 0.49


Approximate thickness of Crown Floor Slab under load

The insulation slabs will be permanentlycompressed by a small percentage due tothe imposed load of the concrete floorand live loads – see chart below.

Typical SpecificationCrown Floor Slab .....mm thick to be closelybutted and placed on the dpm above theflat, level blinded hardcore surface.A stripof perimeter insulation, minimum 25mmthick, to be placed vertically against thesubwalls to the depth of the concrete slab.


KnaufAlcopor recommend Polyfoam Floorboard 220 for thermalinsulation of concrete ground floors with a floating screed. CrownFloor Slab can also be used in this application where a mineralwool product is preferred.


Floating Screed – Polyfoamº Floorboard


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Polyfoam Floorboard is made from HCFC/CFC-free, 100% ozone friendly, extrudedpolystyrene and formed into rigid squareedged boards.The following twocompressive strengths are recommendedfor this application:


• 350 kPa – high loads such as vehicleaccess, including fork lift trucks.

Typical ConstructionA solid concrete floor slab or beam andblock floor overlaid with PolyfoamFloorboard that is covered by awaterproof membrane/separating layer onwhich is laid a minimum 65mm thickreinforced sand/cement screed.Aminimum 25mm thick vertical piece ofPolyfoam Floorboard, the full depth of thescreed, should be placed around theperimeter of each room to minimisethermal bridging.

Typical SpecificationPolyfoam Floorboard 220*/ 350*,(*deleteas required) .....mm thick, to be closelybutted and placed over the whole area ofthe concrete floor. Polyfoam Floorboard, atleast 25mm thick, to be cut and placed tofull depth of screed at the floor perimeter.

The insulation to be overlaid with 1200gauge polythene, taken up and over theperimeter insulation.A sand/cementscreed (65mm thick for dwellings, 75mmthick for other buildings), with wire meshto be laid on top. (NHBC recommend aD49 fabric mesh for use in floatingscreeds.) Floor finish as specified by thedesigner.

Performance

Thermal performancePolyfoam Floorboard 220 has a thermalconductivity of 0.028 W/mK. PolyfoamFloorboard 350 has a thermal conductivityof 0.027 W/mK.



Moisture resistance The boards will not provide a watervapour controlling layer. However, they areresistant to water absorption and can belaid up against wet concrete withoutaffecting thermal performance ordurability.


BBA CertificationPolyfoam Floorboard 220, 350 and 500 arecertified by the BBA.

Installation The insulation should be laid over thewhole of the concrete floor.The surface ofthe floor should be smooth and flat towithin 5mm when measured with a 3mstraight edge. Irregularities greater thanthis must be levelled out.

The perimeter insulation boards are cut tosize and should be securely held in placeto prevent dislodgement by followingwork.

The vapour control layer is laid over theinsulation and turned up at the junctionwith the walls.The screed is laid, with thewire mesh placed at half the screed depth.It is important to compact the screed wellto produce a durable floor surface.

65mm floating screed with mesh reinforcement

25mm Polyfoam Floorboard cut and placedvertically at perimeter

Polythene separating layer/ vapour control layer

Polyfoam Floorboard

Concrete floor slab

Damp proof membrane



U-values (W/m2K)

Thickness Ratio of perimeter (m) to area (m2)

Product (mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

100 0.11 0.15 0.17 0.18 0.19 0.20 0.21

75 0.12 0.17 0.20 0.22 0.23 0.24 0.25

50 0.14 0.20 0.25 0.28 0.29 0.31 0.33

35 0.15 0.23 0.29 0.33 0.36 0.38 0.40

25 0.16 0.26 0.32 0.37 0.41 0.45 0.47


Polyfoam

Floorboard 220



Typical ConstructionA solid concrete or beam and block floorwith reinforced concrete screed and floorcovering. Crown Floor Slab, overlaid bybuilding paper, placed below the screedand vertically around the perimeter.

The insulation slab may be permanentlycompressed by a small percentage due tothe imposed load of the covering.

D49 fabric mesh for use in floatingscreeds.) Floor finish as specified by thedesigner.

Performance


The table gives U-values for a range ofperimeter/area ratios. How to calculateground floor U-values, is explained on page102.

Fire performance

Crown Floor Slab is classified as Class 1surface spread of flame to BS 476: Part 7:1997 and Class 'O' to the BuildingRegulations.

Compressive strengthThe graph shows the compressionresistance curve for Crown Floor Slab underprogressive loading. It relates the appliedload to the compression of the insulant.


The perimeter insulation slabs are cut tosize and should be securely held in placeto prevent dislodgement by followingwork.


Floating Screed – Crownº Floor Slab


KnaufAlcopor recommend Crown Floor Slab for thermalinsulation of concrete ground floors with a floating screed where amineral wool product is preferred.

108



25mm Crown Floor Slab cut and placed vertically atperimeter

1200 gauge polythene

Crown Floor Slab

Concrete floor slab

Damp proof membrane



U-values (W/m2K)


(mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Crown Floor Slab 50 0.14 0.21 0.26 0.29 0.32 0.33 0.35

40 0.15 0.23 0.28 0.32 0.35 0.38 0.39

25 0.17 0.26 0.33 0.39 0.43 0.47 0.49


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Approximate thickness of Crown Floor Slab under load

Typical SpecificationCrown Floor Slab ...... mm thick to beclosely butted and placed over the wholearea of the concrete floor. Crown FloorSlab, minimum 25mm thick, to be cut andplaced to full depth of screed at the floorperimeter.

The insulation to be overlaid with 1200gauge polythene, taken up and over theperimeter insulation.A sand/cementscreed (65mm thick for dwellings, 75mmthick for other buildings), with wire meshto be laid on top. (NHBC recommend a

KnaufAlcopor recommend Polyfoam Floorboard 220 for thermalinsulation of concrete ground floors with a floating chipboarddeck. Crown Floor Slab can also be used in this application wherea mineral wool product is preferred.


Floating Chipboard Deck – Polyfoamº Floorboard


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Polyfoam Floorboard 220 is made fromHCFC/CFC-free, 100% ozone friendly,extruded polystyrene and formed intorigid square edged boards. PolyfoamFloorboard 220 is recommended for useunder chipboard.

Typical ConstructionA solid concrete ground floor slab on awaterproof membrane or beam and blockfloor. Polyfoam Floorboard 220 is laiddirectly on the concrete floor and overlaidwith t&g flooring grade chipboard.

Where there is a risk of moisture fromdrying out of the floor slab, a vapourcontrol layer should be placed directlybelow the chipboard.

Where a beam and block floor has acamber or uneven upper surface a levellingscreed is recommended.

Typical SpecificationThe whole area of the concrete floor to belined with Polyfoam Floorboards 220,…..mm thick.All boards to be closebutted.

The insulation to be (overlaid with avapour control layer of 1000g polytheneand)* covered with 18mm t&g flooringgrade chipboard. (*delete as required)

Performance

Thermal performancePolyfoam Floorboard 220 has a thermalconductivity of 0.028 W/mK.



Moisture resistance The boards will not provide a watervapour controlling layer. However, they areresistant to water absorption and can belaid up against wet concrete withoutaffecting thermal performance ordurability.



The vapour control layer is laid over theinsulation and turned up at the junctionwith the walls.The chipboard is laid in astaggered pattern with all joints gluedusing a waterproof PVA adhesive. Leave anexpansion gap of at least 10mm or 2mmper metre run of floor at the roomperimeter.At doorways or access traps topipework runs the cut edges of chipboardshould be supported on preservativetreated battens.


Chipboard floor deck

Polythene separating layer/vapour control layer

Polyfoam Floorboard 220

Concrete floor slab

Damp proof membrane



U-values (W/m2K)


(mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

100 0.12 0.15 0.17 0.19 0.20 0.20 0.21

75 0.13 0.18 0.21 0.23 0.24 0.25 0.26

50 0.15 0.22 0.26 0.29 0.31 0.33 0.34

35 0.16 0.24 0.30 0.34 0.37 0.40 0.42

25 0.18 0.27 0.34 0.39 0.43 0.47 0.49


Polyfoam

Floorboard 220


Typical ConstructionA solid concrete ground floor slab on awaterproof membrane or beam and blockfloor. Crown Floor Slab is laid directly onthe concrete floor and overlaid with t&gflooring grade chipboard.

Timber battens are placed around theperimeter of the floor, and at doorthresholds, to support the edges of thechipboard.

A vapour control layer is requiredbetween the insulation and the chipboard.

Typical SpecificationThe whole area of the concrete floor tobe lined with Crown Floor Slab, thickness…..mm.All boards to be close butted.Vapour control layer with lapped joints,and t&g flooring grade chipboard asspecified by the designer, to be placed ontop of the insulation. Preservative treatedtimber battens to be placed around theperimeter of the floor, and at door

thresholds to support the edges of thechipboard. Similarly, permanently fittedheavy items should be supported withbattens attached to the subfloor, andrecessed into the insulation.

Performance



Fire performanceCrown Floor Slab is classified as Class 1surface spread of flame to BS 476: Part 7:1997 and Class 'O' to the BuildingRegulations.

Compressive strengthA graph showing the compressionresistance curve for Crown Floor Slabunder progressive loading is given on page106.

InstallationTimber battens are placed around theperimeter of the floor, and at doorthresholds to support the edges of thechipboard. Similarly, permanently fittedheavy items should be supported withbattens attached to the sub-floor, andrecessed into the insulation.The battensshould be screwed to the sub floor andthe chipboard should be screwed to thebattens. Partitions should be built directlyonto the sub-floor.

The insulation is laid over the whole ofthe concrete floor.The vapour controllayer is laid over the insulation and turnedup at the junction with the walls.

The chipboard is laid in a staggered patternwith all joints glued using a waterproof PVAadhesive. Leave an expansion gap at theroom perimeter of at least 10mm or 2mmper metre run of floor.

Floating Chipboard Deck – Crownº Floor Slab


KnaufAlcopor recommend Crown Floor Slab for thermalinsulation of concrete ground floors with a floating chipboard deckwhere a mineral wool product is preferred.

110



Polythene separating layer

Perimeter timber batten

Crown Floor Slab

Concrete floor slab

Damp proof membrane



U-values (W/m2K)


(mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Crown Floor Slab 40 0.17 0.24 0.30 0.34 0.38 0.40 0.42

25 0.18 0.28 0.35 0.41 0.46 0.50 0.53


KnaufAlcopor recommend Crown Wool for the thermal insulation of suspended timber ground floors.


Suspended Timber – Crownº Wool


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Crown Wool is a flexible, unfaced, resilient,low density glass mineral wool quilt.

Typical ConstructionA suspended and ventilated timber groundfloor.The insulation is laid between thejoists and supported on polypropylenenetting.

The drape of the polypropylene nettingmust be sufficient to accommodate the fullthickness of the insulation, so that there isno gap between the insulation and theunderside of the floor deck.

It is recommended that floor joistsrunning parallel with masonry walls shouldbe spaced away from the wall to allow noless than 30mm insulation to be placednext to the wall.

To minimise air leakage at the floorperimeter, the skirting board should have aself-adhesive strip of expanding foamapplied to its lower edge and beads of

sealant applied to its back surface beforefixing.

Typical SpecificationPolypropylene netting to be draped overand between the joists and stapled to thesides of each joist. Crown Wool of .....mmthickness and of width to suit joistspacings, supported on the netting to fittightly under the floor. Crown Wool to beplaced to fully fill in the gap between thelast joist and the perimeter wall.T&gflooring grade chipboard nailed to thefloor joists, all as specified by the designer.

Performance

Thermal performanceCrown Wool has a thermal conductivity of0.040 W/mK.


Fire performanceCrown Wool is classified as non-combustible to BS 476: Part 4: 1970(1984), Class 1 surface spread of flame toBS 476: Part 7: 1997 and Class 'O' to theBuilding Regulations.

InstallationThe depth of the insulation should bemarked on the side of the joists.Thepolypropylene netting should be stapledalong this line and pulled taught to theadjacent joist and stapled again.The nettingshould be pulled over the top of the joistand stapled to the depth of the floorinsulation.The process should be repeateduntil there is netting support to the wholefloor.

The Crown Wool is simply unrolled tocompletely fill the space between thejoists.There should be no air gap betweenthe insulation and the chipboard floor.Joists running parallel with masonry wallsshould be spaced away from the wall toallow no less than 30mm of insulation tobe placed next to the wall.

The chipboard deck should be laid in theusual way, using waterproof PVA glue atthe joints, and allowing a minimum 10mmgap at the room perimeter.

When fixing the skirting board, apply aself-adhesive foam strip to the undersideof the skirting and two beads of sealant tothe back surface.Apply pressure to ensurethe foam strip is compressed immediatelybefore fixing the skirting in place.

Suspended timber floor


25mm Crown Wool between last joist and wall

Polypropylene support netting draped over joists

Crown Wool

Ventilated subspace

Oversite concrete

U-values (W/m2K) of suspended timber ground floor insulated with Crown Wool

U-values (W/m2K)


(mm) 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Crown Wool 200 0.12 0.15 0.16 0.17 0.18 0.18 0.19

150 0.14 0.18 0.20 0.21 0.22 0.23 0.23

100 0.17 0.22 0.25 0.27 0.29 0.30 0.31

80 0.18 0.25 0.28 0.31 0.33 0.34 0.35

60 0.20 0.28 0.33 0.36 0.38 0.40 0.42

Notes:The U-values have been calculated using BS EN ISO 13370: 1998 and assume 48mm wide joists at

600mm centres.

Thermal Insulation

Upper Floors – Design

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Upper FloorsIn the Building Regulations, upperfloors must be insulated when they areexposed to the outside air. Floorsbetween heated and unheated spaces,such as a bedroom floor over anintegral garage, should also beinsulated.

Concrete upper floorsInsulation can be positioned above orbelow the concrete slab.When abovethe slab, the insulation is usually locatedbelow a floating screed or timber floordeck. If only part of a concrete slab isinsulated, careful detailing may beneeded to avoid steps in the floor level.

Insulation located below the slab mustbe protected. Internally this can beplasterboard or other fire resistantboard. Externally a weather and impactresistant board should be used.

Suspended timber upper floorsIn timber joisted floors the insulation isusually located between the joists.

Heated floorsWhen the floor is to be heated by hotwater pipes or electrical cables thenthe position of the insulation will bedetermined by whether the floor slabor the screed is to be heated.

When the heating cables or elementsare installed in the concrete slab, theinsulation is positioned below the slab,with a protective covering ofplasterboard or other fire protectionboard.

If the screed only is to be heated thenthe insulation is laid between thestructural slab and the screed.Theinsulation should be overlaid withbuilding paper which acts as a slip sheetand prevents wet cement entering theinsulation layer.

Position for insulation for upper floors

Concrete upper floor - insulation above concrete slab

Concrete upper floor - insulation below concrete slab

Suspended timber upper floor - insulation between joists

Reinforced floating screed ortimber deck

Insulation

Concrete slab

Screed or timber deck

Concrete slab

Insulation

Protective covering to insulation

Seal below skirting

Timber deck

Insulation between joist and wall

Insulation

Fire resistant ceiling to unheatedspace, or weather protective board if exposed to outside air

KnaufAlcopor recommend Polyfoam Floorboard for the thermalinsulation of concrete upper floors with a floating screed.


Floating Screed – Polyfoamº Floorboard

Upper Floors – Applications

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Polyfoam Floorboard is made from HCFC/CFC-free, 100% ozone friendly, extrudedpolystyrene and formed into rigid squareedged boards.The following twocompressive strengths are recommendedfor this application:


• 350 kPa – non-domestic loading.

Typical ConstructionA concrete floor slab overlaid withPolyfoam Floorboard, covered by a vapourcontrol layer on which a minimum 65mmsand/cement screed is laid.

A 25mm thick vertical piece of PolyfoamFloorboard, the full depth of the screed,should be placed around the perimeter ofeach room to minimise thermal bridging.

Typical SpecificationPolyfoam Floorboard 220*/ 350*, (*deleteas required) .....mm thick, to be closely

butted and placed over the whole area ofthe concrete floor. Polyfoam Floorboard,minimum 25mm thick, to be cut andplaced to full depth of screed at the floorperimeter.

The insulation to be overlaid with avapour control layer, taken up and overthe perimeter insulation.A sand/cementscreed (65mm thick for dwellings, 75mmthick for other buildings),with wire meshto be laid on top. (NHBC recommend aD49 fabric mesh for use in floatingscreeds.) Floor finish as specified by thedesigner.

Performance

Thermal performancePolyfoam Floorboard 220 has a thermalconductivity of 0.028 W/mK. PolyfoamFloorboard 350 has a thermal conductivityof 0.027 W/mK.

The table gives U-values for the aboveconstruction.



BBA CertificationPolyfoam Floorboard 220 and 350 arecertified by the BBA.

Installation The insulation should be laid over thewhole of the concrete floor. PolyfoamFloorboards can be used on a beam andblock suspended concrete floor that is thesubject of the current AgrémentCertificate and installed in accordancewith, and within the limitations imposed bythe certificate.The surface of any floorshould be smooth and flat to within 5mmwhen measured with a 3m straight edge.Provided the surface is smooth and levelthe insulation may be laid directly onto theflooring system. Otherwise lay a thinlevelling screed (this may be the groutwith beam and block systems) prior tolaying the insulation. Irregularities greaterthan those detailed above must beremoved.

The perimeter insulation boards are cut tosize and placed against the wall perimeter.


Concrete upper floor


Polyfoam Floorboard cut and placed vertically atperimeter of screed

Vapour control layer

Polyfoam Floorboard

Concrete floor slab

Typical U-values (W/m2K) of 150mm concrete upper floor insulated with Polyfoam Floorboard

Product Thickness (mm) U-Value (W/m2K)

Polyfoam Floorboard 220 100 0.25

75 0.32

50 0.45


75 0.31

50 0.44

Notes:The U-values have been calculated to BS EN ISO 6946:1997.

Floating Chipboard Deck – Polyfoamº Floorboard


KnaufAlcopor recommend Polyfoam Floorboard for the thermalinsulation of concrete upper floors with a floating chipboard deck.

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Polyfoam Floorboard is made from HCFC/CFC-free, 100% ozone friendly, extrudedpolystyrene and formed into rigid squareedged boards. Polyfoam Floorboard 220 isrecommended for use under chipboard.

Typical ConstructionA concrete floor slab overlaid withPolyfoam Floorboards and finished with18mm t&g flooring grade chipboard.Anintervening vapour control layer is notrequired unless the underside of the flooris exposed to the outside air.

Typical SpecificationPolyfoam Floorboard 220, ..... mm thick, tobe closely butted and placed over thewhole area of the concrete floor.

The insulation to be (overlaid with avapour control layer and)* covered with18mm t&g flooring grade chipboard.(*delete as required)

Performance

Thermal performancePolyfoam Floorboard 220 has a thermalconductivity of 0.028 W/mK.

The table gives U-values for the aboveconstruction.



Installation The insulation should be laid over thewhole of the concrete floor. PolyfoamFloorboards can be used on a beam andblock suspended concrete floor that is thesubject of the current AgrémentCertificate and installed in accordancewith, and within the limitations imposed bythe certificate.The surface of any floorshould be smooth and flat to within 5mmwhen measured with a 3m straight edge.Provided the surface is smooth and levelthe insulation may be laid directly onto theflooring system. Otherwise lay a thinlevelling screed (this may be the groutwith beam and block systems) prior tolaying the insulation. Irregularities greaterthan those detailed above must beremoved.

The vapour control layer is laid over theinsulation and turned up at the junctionwith the walls.The chipboard is laid in astaggered pattern with all joints gluedusing a waterproof PVA adhesive. Leave anexpansion gap of at least 10mm or 2mmper metre run of floor at the floorperimeter.At doorways or access traps topipework runs, the cut edges of chipboardshould be supported on preservative-treated battens.

Typical U-values (W/m2K) of 150mm concrete upper floor insulated with Polyfoam Floorboard 220

Product Thickness (mm) U-Value (W/m2K)


75 0.31

50 0.42

Notes:The U-values have been calculated to BS EN ISO 6946:1997.

Concrete upper floor

18mm flooring grade chipboard

Vapour control layer

Polyfoam Floorboard

Concrete floor slab

KnaufAlcopor recommend Crown Wool for the thermal insulationof suspended timber upper floors.


Suspended Timber Floor – Crownº Wool


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Crown Wool is a flexible, unfaced, resilient,low density glass mineral wool quilt.

Typical ConstructionA timber joist floor finished with 22mmt&g flooring grade chipboard, the undersidefinished with 6mm external grade sheeting.Crown Wool laid between the joists tofully fill the void.

Typical SpecificationCrown Wool ..…mm thick, placedbetween joists and supported by 6mmexternal grade sheeting. Flooring gradechipboard, as specified by the designer, tobe fixed to the joists.

A strip of Crown Wool to be placed tofully fill in the gap between the last joistand the perimeter wall.

Performance

Thermal performanceCrown Wool has a thermal conductivity of 0.040 W/mK.

The table gives U-values for thisconstruction insulated with Crown Wool.It can be used to determine whichcombination will satisfy the BuildingRegulations U-value requirements forabove-ground floors.

Fire performanceCrown Wool is classified as non-combustible to BS 476: Part 4: 1970(1984), Class 1 surface spread of flame toBS 476: Part 7: 1997 and Class 'O' to theBuilding Regulations.

Timber suspended upper floor

Perimeter seal to skirting

22mm flooring grade chipboard

Minimum 30m Crown Wool betweenlast joist and wall

Crown Wool

Floor joists

External grade sheeting

Typical U-values (W/m2K) of timber joist upper floor insulated with Crown Wool

Product Thickness (mm) U-value (W/m2K)

Crown Wool 200 0.25

150 0.32

100 0.44

Notes:The U-values have been calculated to BS EN ISO 6946:1997 and assume joists are 48mm wide, spaced

at 600mm centres and are the same depth as the insulation.

InstallationThe Crown Wool is simply unrolled to fillthe space between the joists.Theinsulation should rest on the ceiling. Joistsrunning parallel with masonry walls shouldbe spaced away from the wall to allow noless than 30mm of insulation to be placednext to the wall.


Refurbishment of Separating Floors – Rocksil Slab RS33


KnaufAlcopor recommend Rocksil Slab RS33 for upgrading the fireperformance of existing suspended timber floors to a one hourrating where the existing ceiling is being retained.

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Rocksil Slab RS33 is a semi-rigid slab ofrock mineral wool with a density of 33kg/m3.

Typical ConstructionIn some situations there is a requirementfor a party floor to achieve a one hour firerating.The use of Rocksil Slab RS33 in asuspended timber floor achieves a onehour fire resistance, whilst allowing theexisting ceiling to be retained.

The construction shown will provide aone hour fire rating with 100mm RocksilSlab RS33 placed between 200mm deeptimber joists.

To achieve a one hour fire resistance, thefloor deck should be at least 18mm thickt&g chipboard or timber boarding, and anyceiling can be used.

Rocksil Slab RS33 can also be used in lieuof or as well as Crown Wool in theapplication shown on the previous page toachieve a one hour fire resistance.

Typical SpecificationLay 100mm Rocksil Slab RS33 on 25mmchicken wire mesh, stapled to sides ofjoists at least 40mm up from ceiling leveland at 600mm centres.The joists shouldbe at least 200 x 37mm and spaced at notmore than 600mm centres.The flooringboard to be at least 18mm thick.

Performance

Fire performanceRocksil Slab RS33 is classified as non-combustible to BS 476: Part 4: 1970(1984), Class 1 surface spread of flame toBS 476: Part 7: 1997 and Class ‘O’ to theBuilding Regulations.

InstallationThe chicken wire should be stapled to theside of the joist, near the bottom of thejoist.The netting is then unrolled acrossthe ceiling and stapled to the side of theadjacent joist.The process should berepeated until there is netting support tothe whole floor.

The Rocksil Slab is simply placed on thewire mesh to be in close contact with theceiling.The Rocksil Slab should fully fill thespace between the joists and all jointsshould be close butted.


One hour timber separating floor with floating platform

Existing wall

18mm chipboard

100mm Rocksil Slab RS33

Chicken wire stapled to joists

Existing ceiling

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