2 trade preambles 2.1 materials - crawley...the tree crawley specification: trade preambles,...

THE TREE CRAWLEY SPECIFICATION: TRADE PREAMBLES, MATERIALS & WORKMANSHIP

Oxley Conservation Ltd 1 of 27 May 2015

2 TRADE PREAMBLES

2.1 MATERIALS

Wherever possible all materials should be obtained from sustainable, well-managed and/or local sources.

2.1.1 Non - hydraulic lime putty

To be derived from fresh, high calcium, non-hydraulic quicklime, slaked in an excess of water under controlled conditions and allowed to mature for at least three months.

All lime putty to be kept well covered during storage to prevent drying out.

2.1.2 Hydraulic lime

The source of hydraulic lime to be St Astier Natural Hydraulic.

The hydraulic lime is to be used in accordance with the manufacturer’s technical advice and recommendations.

2.1.3 Sharp Sand

The sand is to be clean well graded sharp sand that meets with the approval of the Historic Buildings Consultant.

2.1.4 Soft and Silver Sand

The sand is to be clean, washed and well graded fine sand with a maximum diameter of 3mm that meets with the approval of the Historic Buildings Consultant.

Soft sand is to be as dug, to the approval of the Historic Buildings Consultant.

2.1.5 Limewash and Lime Paint

To be derived from the aforementioned lime putty and diluted as required.

Natural earth pigments to be used to achieve the desired finish.

Lime Paint to be St Astier Natural Hydraulic lime paint derived from feebly hydraulic lime [NHL2]. Product information and a list of distributors can be obtained from St Astier: www.stastier.co.uk



2.1.6 Rainwater and other Cast Iron Goods

Replacement CAST IRON SECTIONS to be of a quality and profile to match the existing from the range of:

J & JW Longbottom Ltd.

Bridge Foundry

Holmfirth

Nr Huddersfield

HD9 7AW

T: 01484 682141

Allow for all necessary compatible stop ends, outlets and fixings and all gutters to be provided with an adequate fall to the outlets.

All rainwater goods should be factory coated with a matt black polyester powder coating and any defects arising during handling repaired according to the manufacturer’s instructions.

All gutter brackets should be galvanised mild steel brackets

2.1.7 Bricks

For general repairs the bricks are to be new handmade imperial light multi bricks from H.G. Matthews Brickworks or Bovingdon Bricks Ltd.

For use in repairs and modification of existing brickwork bricks are to be selected to match the existing in size, type, strength, colour and texture to the approval of the Historic Buildings Consultant from the range of from H.G. Matthews Brickworks, Dunton Brothers Ltd or Bovingdon Bricks Ltd.

Product information is available from:

H.G. Matthews Brickworks, The Brick Works, Bellingdon, Chesham, HP5 2UR. Tel: 01494 758212 www.hgmatthews.com

Bovingdon Brickworks, Ley Hill Road, Bovingdon, Hertfordshire HP3 0NW. Tel: 01442 833176, Fax 01442 834539, Email [email protected], www.bovingdonbricks.co.uk

2.1.8 Stone

For the purposes of pricing stone the stone to match the existing. Allow for:

• Green Sandstone

• Horsham Stone slate

2.1.9 Roof Tiles & Vertical Tile Hangings

New clay tiles to be handmade clay peg tiles to match the existing in size, type, colour and texture to the approval of the Historic Buildings Consultant selected from the Aldershaw range.

All size, type, colour and range to be confirmed

Product information is available from Aldershaw Handmade Tiles Ltd, Pokehold Wood, Kent Street, Sedlescombe, Nr. Battle, East Sussex, TN33 0SD, Tel: 01424 756777, www.aldershaw.co.uk



2.1.10 Timber

Wherever possible timber is to be obtained from sustainable, well-managed local sources. The timber, particularly softwoods, to be approved by the Forest Stewardship Council (FSC) and should bear the FSC logo.

Replacement timbers should match the remaining timber in species and also in the manner of conversion: that is boxed heart, quartered etc. - unless specifically expressed otherwise.

All new timbers are to be naturally durable rather than relying upon chemical preservative treatments. This to be achieved through careful selection of timber and good detailing and protection rather than reliance upon chemical preservative treatments. Where pre-treated timbers need to be used the express approval of the Historic Buildings Consultant needs to be sought prior to ordering of any new timber.

Second hand/salvaged timber is not to be used. The written consent of the Historic Buildings Consultant has to be obtained before any second hand/salvaged timber is used. Where consent for second hand/salvaged timber is provided the timber must have a provenance of origin.

The timber should be of a quality to match the existing. The amount of wane should not exceed that which already exists.

The timber should be free from major defects.

European oak, elm or good quality softwood should be used to match the other timbers.

Softwood to be the heartwood of Douglas Fir or European Larch.

The timbers to be from the heartwood, sapwood is to be kept to a minimum.

Timber to be air dried for a year per inch of its thickness (up to 5 years) in a section similar to its final size.

When scarfing/splicing timber the moisture content of the new should match as closely the old as possible.

Green (unseasoned) oak should only be used for replacement timbers where its shrinkage will not cause structural problems and is specifically approved by the Historic Buildings Consultant.

The timbers should be stored under cover and off the ground in areas with good ventilation.

Adequate protection should be provided to the building and the sequence of construction suitably programmed to ensure that the moisture content of the timber is not increased to such an extent that it would become prone to fungal and/or insect attack. The moisture content of the timber should be kept below 20% to reduce the risks of timber decay.

Untreated softwood used for external use to be heartwood containing no sapwood.

All new softwood timber for structural purposes to be to Grade C24.

2.1.11 Roofing battens

Unless specified to the contrary, all roofing battens to be 50mm x 20mm pre-treated softwood battens in minimum lengths of 1200mm.



2.1.12 Replacement rafters

The rafters in need of replacement that are to remain exposed are to be cut to match the manner in which the original rafter and/or adjacent rafters were sawn.

2.1.13 Nails and metal fixings

All nails and metal fixings to be non-ferrous.

All fixings, screws, bolts and coach-bolts for fixing structural metal straps to be stainless steel.

2.1.14 Lead

All lead used should meet the standards of BS1178

2.1.15 Metal straps

Stainless steel straps to be purpose made stainless steel angle brackets/straps pre-drilled for fixing. Stainless Steel to SEN 10088-2 grade 1.4301 (Grade 304).

Blacksmith’s straps to be purpose made mild steel straps pre-drilled for fixing

All mild steel straps to be painted with a rust-neutralizing inhibitor; two coats of zinc-phosphate primer, two layers of undercoat and two topcoats of oil-based paint.

2.1.16 Wood-fibre insulating boards

Wood-fibre boards should be from the Pavatex range available from Natural Building Technologies Ltd, The Hangar, Worminghall Road, Oakley, Bucks HP18 9UL, www.natural-building.co.uk.

Wood-fibre boards for externally insulating timber framed walls should be “Isolair” interlocking, latex impregnated, waterproof, dense thermal/acoustic insulation board.

Fixings for Pavatherm Plus boards on roofs and Isolair board on timber studded walls should be EJOT VHT-4 4.8mm diameter screw fasteners of sufficient length to embed at least 40mm into the rafters or studs. For product information contact EJOT UK Ltd, Tel. 01977 687740, www.ejot.co.uk.

Basecoat renders, topcoat renders, and equalisation paints for Diffutherm boards should be from the range of Baumit Bayosan, available from Natural Building Technologies. Ltd.

Wood-fibre boards should be stored flat and dry. Edges should be protected to prevent damage to any tongue & groove.

2.1.17 Other insulation materials

Insulation batts should be made from natural fibres. Suitable batts can be purchased from Natural Building Technologies.

Insulation to sloping ceilings of warm roof [RMR 2.3.1.7] to be UdiRECO 100mm wood fibre insulation boards.

http://www.backtoearth.co.uk/product/udireco-100mm-wood-fibre-insulation-boards



2.1.18 Roofing felt, breather paper

Roofing felt and breather paper to be “Roofshield 240 Underlay” from the A. Proctor Group.

Product information is available from A Proctor Group UK Ltd, The Haugh, Blairgowrie, Perthshire, UK,

PH10 7ER, Tel 01250 87226, www.proctorgroup.com

The following is provided to inform on fixing methodology only. The materials are to be stored, handled and applied in accordance with the manufacturer’s recommended practices (www.proctorgroup.com).

Handle carefully to prevent tears and punctures and repair with adhesive tape any which do occur.

If tear occurs, batten above should be lifted, cut new section of underlay, remove torn section by cutting close to sides of rafters, slide up new section of underlay, staple sides to rafters and finally nail down batten above.

The underlay is to be laid horizontally across the rafters, parallel to eaves, starting at the eaves and working to the ridge maintaining consistent tautness.

The green side needs to be uppermost, the white side to the underside.

2.1.19 Rooflights

Rooflights should be from the range of:

The Rooflight Company

Wychwood Business Centre

Milton Road

Shipton-under-Wychwood

Oxfordshire OX7 6XU

Email: [email protected]

Tel: 01993 833 108

Fax: 01993 831066

2.1.20 Biocide

To be Wykamol Microtech Biocide (www.wykamol.com).

Biocides are only to be used where they are specifically approved by English Nature and instructions have been specifically confirmed by the Historic Buildings Consultant.

2.1.21 External paints and fillers

All paints used on external timber and metal work to be “Demi Dekk Ultimate” range from Jotun.

Colours/tints to be approved by sample.



2.1.22 Internal paints

All paints used on internal walls to be “Claypaint” from the range of EarthBorn Paints

Brush Mate, Frodsham Business Centre, Bridge Lane, Frodsham, Cheshire, WA6 7FZ

Tel: 01928 734171, www.earthbornpaints.co.uk.

Colours/tints to be approved by sample.

2.1.23 Self-Level Floor Renovation

To be Flowcrete Isocrete Self Renovation [Green] to be used in accordance with the manufacturer’s/supplies recommendations.

2.1.24 Internal boards [Fermacell]

Fermacell boards are to be used, as scheduled/instructed, for partitions, ceilings and floors and to be installed in accordance with the manufacturer’s recommendation [refer to the Fermacell Handy Guide].

http://www.fermacell.co.uk/en/docs/Fermacell_Handy_Guide_s_2013.pdf

2.1.25 Internal floor coverings

To be Forbo Eternal Original vinyl floor covers as scheduled/instructed.

http://www.forbo.com/flooring/en-gl/products/project-vinyl/eternal-original/bbhdfa

Floor coverings to be approved by sample.

2.1.26 Daub recipe

Allow for: o 2 x parts crushed chalk o 1 x part earth dug from a local source o ½ part gravel 10 mm o 1 part coarse stuff (made up of 1 part lime putty to 3 parts well graded sharp sand) o Straw to be added to the final mix as necessary to achieve a satisfactory bind – allow for 1

part of straw to every 6 parts of the final mix of earth



2.2 REPAIRS

2.2.1 Workmanship

The whole of the works is to be executed in the best and most workmanlike manner and with materials of the best description in accordance with the directions and to the satisfaction of the Historic Buildings Consultant.

The appropriate sections of work are to be inspected and measured from time to time before being covered up and the Contractor is to give due notice and is to afford every facility to the Historic Buildings Consultant for inspecting and checking the work.

2.2.2 Dry & Inclement Weather Conditions

During warm, dry and/or windy weather, new masonry work, pointing and rendering should be kept covered with polythene sheeting and dampened hessian to inhibit the rate of drying out.

During driving rain the finished work should be kept covered with sheeting until set and for a minimum seven days after at the Historic Buildings Consultant’s discretion.

No masonry or rendering work to be carried out when the temperature is below +3ºC on a falling thermometer or below +1ºC on a rising thermometer.

All work is to be protected against damage by frost at night by being covered with insulating material (sacking, boarding, etc.).

No masonry or rendering work to be carried out when temperature is above + 30ºC. All work to be fully protected against direct exposure to the sun, hot temperatures and strong winds by hessian which is be kept free of the wall and kept regularly dampened down.

Any damage caused by dry, windy, inclement or frosty weather to work executed under this Contract up to the time of Practical Completion is to be raked out/carefully removed and made good at the Contractor’s expense.

2.2.3 Machine held power tools

The only power tools to be used in the repair of the building and the removal of cement renders and/or pointing is to be the Arbortech AS170 and/or the variable speed oscillating Fein MultiMaster tool.

All operators that are to use the Arbortech AS170 and/or the Fein MultiMaster are to illustrate to the Historic Buildings Consultant their level of competence and understanding of the techniques and manner in which the cement-based mortars are to be removed. Work is only to start on the authority of the Historic Buildings Consultant once he has been satisfied as to the competence and suitability of the operator(s).

o The Arbortech AS170 and/or the Fein MultiMaster are to be fitted and used with appropriate disc cutters to cut the cement-based mortars.

o Only fit and use sharp disc cutters. Blunt or damaged cutters are not to be used.

o Take great care not to cut into or damage brickwork or adjacent fabric.

o Carefully lever and remove the cement-based mortars from the walls in small sections with sharpened tungsten chisels (see above).

o Sufficient allowance needs to be made for replacing damaged blades and cutters.



2.2.4 Lime Mortar & Plaster Mixes

A Lime putty ‘coarse stuff’

1 x part lime putty

2 x parts clean well graded sharp sand

1 x part soft sand as dug

Mix the aggregates and lime together to form a coarse stuff at least a week before use. Ensure that they are well beaten and thoroughly mixed to ensure a good dispersion of lime and coating of all particles of aggregate.

B Hydraulic lime mortar

1 x part by volume hydraulic lime [feebly or moderately to be confirmed by the Historic Buildings Consultant for each individual area]

1½ x parts by volume well graded sharp sand

½ x part as dug soft sand

This recipe applies for both the feebly and hydraulic mortar mixes for this specification.

2.2.5 Internal two-coat lime putty plaster

A first coat of 9mm to 12mm 1: 3 plaster (lime putty: 2 parts well graded sharp sand and 1 part soft sand) reinforced with horse hair at 4kg/m³.

Scratch a key for the next coat by making a lattice of diamond shaped scratch marks diagonally to the laths at approx. 45° angles about 25mm apart in the plaster/render using a pointed lath.

The second coat to be a 6mm 1: 1: 1 render (lime putty: sieved soft sand: silver sand). The sand to be a max. of 3mm in diameter.

Finish with a cross-grained wooden float to achieve an ‘open-grained’ finish.

The total thickness to match existing finishes. The thickness of the coats can be adjusted to allow for any variations.

2.2.6 Preparation of mixes

Where mortar is mixed on site, mix up enough lime/sand mortar at the start of the contract to complete the work set out in the Schedule of Works.

All coarse-stuff mortar (whether mixed on site or supplied to site) to be stored in plastic tubs (or dustbins) or on timber sheeting and protected from the weather and contamination by polythene sheeting/damp hessian.

All lime putty coarse-stuff to be re-mixed ‘knocked-up’ again immediately before use to ensure a good dispersion of lime and coating of all particles of aggregate.

2.2.7 Preparation of hydraulic lime mortar

The preparation of hydraulic lime mortar is to follow the manufacturer’s instructions.

The following assumes that the mortar will comprise of 1 part (feebly) hydraulic lime to 2 parts sand. The hydraulic lime mortar mix to be prepared as follows:

Mix the lime and sand dry to improve the blending of the materials by placing the full measure of hydraulic lime and an equal measure of sand and into the mixer.

Tap the mixer to free any trapped air within the mix.

Place the remaining measure of sand into the mixer and mix thoroughly.

Once the mix is well blended let the dry mix stand for a few minutes and mix again before adding water to achieve a good working consistency.

Excess water is to be avoided.

Allow the mortar to be well mixed before use.



2.2.8 Pointing

A Preparation for repointing

The extent that the existing mortar is to be removed is to be agreed with the Historic Buildings Consultant before proceeding with the work. Preparation to be carried out as follows:

Always work from the top of the walls downward.

Carefully remove hard/cement pointing with sharp chisels.

All tools used to remove existing pointing/mortar are to be narrower than the joints.

Great care is to be taken not to damage the corners and arrises of the brickwork.

No mechanical cutting appliances are to be used.

Where hard/cement pointing cannot be removed without damaging the brickwork it should be left in place.

Rake out the joints with a blunt screwdriver, or similar instrument, to at least twice the width of the joint.

Brush out all loose debris and dust from the raked out joints.

Wash out the joints and wet the wall down to reduce the level of initial suction of moisture.

The masonry to be thoroughly dampened down before re-pointing allowing a period of free water to dry out.

Repeat dampening down on unpointed areas as the work proceeds as necessary to ensure masonry is damp when re-pointed.

B Re-pointing

Point up raked out joints as follows:

Press the mortar well into the joints filling all voids.

Keep the mortar away from the surface of the brickwork at all times.

Pack the joints with mortar.

Remove excess mortar.

Use a brush to compact the joint once the mortar starts to set. Leave the mortar slightly recessed from the edge of the brickwork, exposing sand particles to provide a textured finish.



2.2.9 Plasterwork

The specification for rendering and plasterwork described below may be subject to alteration following preparation of samples. The following clauses therefore should be treated as nominal for pricing purposes only, to be amended as necessary. Except where otherwise specified the term “render” in this section includes external and internal renders and plasters.

A Preparation rendering onto laths

Screw new laths at approximately 9mm spacing.

Thoroughly wet down the laths the day prior to plastering and two hours prior to the rendering work commencing. Avoid the laths being so dry that they will absorb moisture rapidly from the first cot of render when it is applied.

Thoroughly wet down the trimmed edges of the existing render to reduce excessive suction.

B Wetting down

The walls and render are to be kept damp and wetted down between all operations/coats with a pump-style garden spray – using a fine/mist spray – until the walls are thoroughly dampened. This method to be used between all operations and stages of rendering.

C Internal two coat lime plaster

Allow for providing two-coat plaster finishes:

Apply a first coat of 9mm to 12mm using lime putty course stuff (see mix in 2.2.3 A above) reinforced with horse hair at 4kg/m³.

Scratch a key for the next coat by making a lattice of diamond shaped scratch marks diagonally to the laths at approx. 45º angles about 25mm apart in the plaster using a pointed lath.

The second coat to be a 6mm using lime putty fine stuff (see 2.2.3 B above).

Finish with a cross-grained wooden float to achieve a ‘vernacular’ / ‘open-grained’ finish.


D Internal three coat lime plaster

Allow for providing three-coat plaster finishes:

Apply a first coat of 9mm to 12mm using lime putty course stuff (see mix above) reinforced with horse hair at 4kg/m³.

Scratch a key for the next coat by making a lattice of diamond shaped scratch marks diagonally to the laths at approx. 45º angles about 25mm apart in the plaster using a pointed lath.

Apply a second coat the same as the first coat.

The third/top coat to be a 6mm using lime putty fine stuff (see mix above).

Trowel the top coat to achieve a fine decorative finish.




2.2.10 Shelter coating

o Lime shelter coats are to be applied to consolidate friable stone as instructed.

o Consolidate with lime mortar grout to all flakes and exfoliating edges.

o Fill cracks and cavities with lime mortar and ‘weather’ profile to shed water.

o Apply 1 to 2 applications of shelter coat, carefully colour matched to masonry, to damp surface of stone using a soft bristle brush.

o Compact shelter coat using clean washed hessian.

o Control drying out by spraying with mist of clean water, hanging clean damp hessian over the work and covering with a polythene tarpaulin.

o Do not apply shelter coat if there is a risk of frost.

2.2.11 Removal of biological growth

Carefully remove biological growth with wooden spatulas, metal scrapers and stiff bristle brushes where this will not cause damage. If the substrate is friable or likely to be damaged remove as much by hand as possible.

Apply biocide solutions such as Microtech Biocide in accordance with the manufacturer’s instructions and the relevant COSHH assessment and other health and safety requirements.

Following application clean down after 5 days with natural bristle brushes and re-apply biocide to minimise further re-growth.



2.2.12 Stonework

A General:

o Obtain stone to match existing, which must be free from defects that will affect its workability and free from defects visible in completed work.

o The stone is to be thoroughly seasoned at the time of delivery.

o Cutting, dressing, laying and jointing of stone to be carried out by skilled masons.

o All stainless steel fixings, dowels, pins and cramps are to be Grade 316 Austenitic.

B Cutting out complete stones for replacement:

o Rake out joints using a fine-toothed mason’s saw and hooked knife blade.

o Lever stones from position without damage to surrounding work.

o Remove all loose bedding and backing material, fixing dowels and cramps from voids and wash out with clean water.

o Use timber blocks to prop adjacent work where necessary.

C Cutting out for piecing in or mortar repairs:

o Cut out area of decay or spalling back to sound stone using small sharp chisels or sharp saw blades to an approximate depth of 75 mm.

o Cuts are to be raked backwards to form dovetail joints, or if fixing with pins or dowels cut square.

o Cut outs are to be neat with dead flat surfaces to receive new stone, or keyed to receive mortar repairs.

o Remove all loose material from cut out using a bristle brush and wash out with clean water.

D Preparation of stone for replacement and piecing-in:

o Cut stones to full dimensions for bonding with facework and backing.

o Take all necessary measurements and moulds for new stones direct from existing stones to be repaired/replaced or, if stones are missing, from adjacent work.

o Work the exposed and joint face of each stone to a square and true plane surface free from hollow rough areas.

o Prepare stones so that the natural bed is vertical and at right angles to wall face in cornices and other projecting stones, parallel to the radial centre line of each stone, and at right angles to the wall face, in arches.

o Finish new stones on all exposed faces to achieve a plain worked finish to match the original finish of existing stonework.

o Drill holes for dowels or pins to equal depth in adjacent stones.

o Cut dovetail channels in adjacent stones for cramps.



E Laying and bonding new and reinstated stones:

o Lay and bond new and reinstated stones in the exact position previously occupied.

o Provide stainless steel dowels, pins and cramps as necessary.

o Ensure that bond, joint size and any other special feature are replicated to match existing.

o Flush out voids with clean water.

o Dampen stone for reinstatement/replacement. Spread a mortar bed on the stone and tamp into place using the mortar bedding as a lubricant.

o Pack mortar around the stone when set in position using a suitably sized pointing iron. Push mortar home firmly.

o Set joint slightly back from stone face, or to match existing.

o Where arrises are eroded set joint back to round edge avoiding the creation of ledges that may trap water.

o Match existing surrounding work by stippling with a wet bristle brush following the initial set of the mortar.

o Wash surrounding work with clean water to prevent staining.

F Piecing-in new stone:

o Work the new stone to provide a tight fit into the cavity and dress to a profile matching the surrounding work. New joints are to be of the minimum width necessary to place the repair. Cut 'V' shaped sinkings on joint faces to help the stone grip the backing bed.

o Protect adjacent work to prevent mortar staining.

o As necessary drill holes to receive stainless steel pins or dowels of a suitable size for the repair.

o Remove dust from holes and inject resin or mortar in such a way that air will not be trapped. Pins should be cut to length before injecting resin.

G Pinning/stitching fractures & cracks in stonework:

o Agree size and number of pins before commencing work.

o Drill holes one side of crack through the stone diagonally to receive suitably sized stainless steel threaded rod. Holes are to be oversize in diameter, e.g. 12 mm for 10 mm rod.

o Remove all dust from the holes by blowing and/or flushing out with clean water.

o Cut rod to length, the head of the rod is to be set back into the hole by 20 mm.

o Inject NHL 3.5 hydraulic lime grout into the hole ensuring that no air is trapped at the end of the hole, fill the hole from the deepest point back to the surface.

o Insert the treaded rod by gently pushing and screw twisting it so that surplus grout is driven out of the hole. Collect and remove all surplus grout immediately.

o Once the grout has semi set remove surplus grout from the head of the hole.

o Once the grout is fully set point in the top 20 mm with matching mortar.

o All stainless steel is to be Grade 316 Austenitic.

H General clean:

o Carefully remove dirt and loose surface accumulations from the face of the stonework with stiff bristle brushes.

o Review the condition of the stonework upon completion of the general clean and the extent and nature of further cleaning and repair with the Historic Buildings Consultant.



2.2.13 Painting and limewashing

A General

o All painting and proprietary systems are to be carried out strictly in accordance with the manufacturer’s recommendations.

o The paints shall be thoroughly mixed or stirred before use with a mechanical whisk. The paints shall be stored so as to minimise exposure to extreme temperature.

o All paints, primers etc. to be applied by brush.

o All sundries, all fillers, thinners, cleaners etc. should be those that are as recommended as being appropriate and compatible by the manufacturers as suitable for use with each particular paint system.

o Each coat of paint shall be allowed to harden before the next coat is applied.

o The whole of the work shall be finished to tints and colours selected by the Historic Buildings Consultant. The Contractor to include for painting samples in situ as required by selection and approval of the Historic Buildings Consultant.

o Provide all necessary dust sheets and other protective materials to protect floors, fittings and decorations during the course of the works.

o Patch up as necessary on completion; clear and cart away all rubbish and surplus materials.

o Clean off all paint stops, stains etc., clean off paint and other marks from glass on both sides and leave the whole of the work to the satisfaction of the Historic Buildings Consultant.

B Preparation of surfaces for painting

o Paint shall not be applied to damp surfaces. All surfaces to be free from condensation, dirt, etc. before application of each coat.

o All areas to be painted are to be cleared of rubbish prior to the commencement of the work and adequate precautions taken to ensure that areas are reasonably dust free until all paintwork is completely dry.

o All woodwork to be painted shall be cleaned to remove dirt, grease etc., rubbed down or scraped smooth and dusted off.

o A thin coat of knotting shall be applied to all knots to internal joinery. After priming, all cracks, nail holes, etc., shall be made good with hard stopping. The knotting is to be best quality shellac knotting.

o All locks and fastenings are to be removed before the painting processes are commenced and are to be refixed in position on completion.

C Primers and Undercoats

o Where a particular paint type is specified the manufacturers recommendations are to be followed for the number and type of primer coats, undercoats and top coats as appropriate for the substrate. Failure to mention primer coats or undercoats in the schedule of works, or failure to list multiple coats, does not imply such coats are not required and no extras costs will be allowed for such coats.

o Primers and undercoats shall be from the same manufacturer to avoid any possible incompatibilities.

o Each coat of paint shall be allowed to harden before the next coat is applied.



2.2.14 Lime putty limewash

o Allow for 3 no. coats of limewash.

o Mix a single batch of limewash (colour to match stonework) of a sufficient quantity to apply final 3 no. coats to the specified areas.

o Thoroughly wet down before each coat.

o Apply coats at 24 hour intervals, or longer if necessary (allow full carbonations of each coat before applying the next).

o Following application of limewash allow for removal of all splashing, drips, spills etc. from surrounding fabric, ground, pavements, woodwork, rainwater goods etc. Allow for thorough cleaning of all windows in any elevation limewashed.

2.2.15 Lime putty slurry coat

Same procedures as for lime putty limewash but add 1 x part ‘coarse stuff’ mortar to 6 x parts

limewash.

2.2.16 Cleaning

Following application of paint, limewash and/or limewash slurry allow for removal of all splashing,

drips, spills etc. from surrounding fabric, ground, pavements, woodwork, rainwater goods etc.

Allow for thorough cleaning of all windows.

2.2.17 Preparing metal work

o Remove all loose rust, dirt, grease and salt with Hammerite Brush Cleaner & Thinners and rinse with clean water. Allow time to dry. Degrease surface again if necessary. Rub down gently and prime immediately using a red oxide primer.

o Exercise care when rubbing down old paintwork – always assume that the paint could contain lead and take precautions accordingly.



2.2.18 Windows and doors

A For each of the windows listed below, “refurbish” shall mean:

Freeing and removal of casements and sashes (express permission required from the Historic Buildings Consultant prior to the removal of any window frames, casements or sashes). Wherever possible windows to be retained and worked in-situ. For pricing purposes allow for the freeing, removal and reinstatement of all casement and sashes.

Making repairs as required to the sashes and to the window frames (see below for specific repair allowances). All softwood (all for Douglas fir) to be fully knotted and primed, lightly rubbing down primed areas; cleaning off and applying 1 x coat of primer prior to fixing.

Checking of sash cords and pulleys (where appropriate). Assume all cords, 50% of pulleys and 25% of lead weights have to be replaced.

Checking of hinges: allow for 100% replacement but retaining all historic hinges where possible.

Reinstallation of sashes once decoration (see below) is complete, oiling, rebalancing and adjusting as required to ensure that windows operate fully and properly.

B Repairs to be carried out in accordance with SPAB Technical Pamphlet 13: Repair of Wood Windows.

C For each of the doors listed below, “refurbish” shall mean:

Freeing and removal of door.

Making repairs as required to the doors and to the door frames (see below for specific repair allowances).

All softwood to be fully knotted and primed, lightly rubbing down primed areas; cleaning off and applying 1 x coat of primer prior to fixing.

Checking of hinges: allow for 100% replacement but retain historic hinges where possible.

Reinstallation of doors once decoration (see below) is complete, oiling, rebalancing and adjusting as required to ensure that the door operates properly.

D Window and door furniture should ALL be retained unless its removal is specifically sanctioned by the Historic Buildings Consultant.

E For each of the sash windows listed below, “draught-proof” shall mean fitting detachable brush-pile draught excluders of the appropriate depths to the parting bead, staff bead, mid and bottom rails.

F For each of the side hung casement windows listed below, “draught-proof” shall mean fitting detachable brush-pile draught excluders of the appropriate depths to the circumference of each casement.

G For each of the doors listed below, “draught-proof” shall mean fitting detachable brush-pile draught excluders of the appropriate depths to the circumference of the door.

H For each of the doors and windows listed below, “decorate” shall mean:

Thoroughly rubbing down and preparing all existing and new joinery.

Replacing all putty in the window, taking great care not to damage the glazing.

Carefully cutting back all over-painting of glass.

Applying 2 x coats of undercoat in accordance with the manufacturer’s recommendations.

Applying 2 x coats of top-coat external eggshell paint in accordance with the manufacturer’s recommendations.

All edges of opening windows and doors are to be dry before closing.

Making good damage to painted finishes made during repair work, blending in the matching paint and finishes.

I Colours for painting of external joinery to be confirmed – subject to trial samples.



2.2.19 Leadwork

A All leadwork is to be carried out by a member of the Lead Contractors Association who specialises in lead roof work and is recognised by the Lead Contractors Association as having a minimum current vetting grade of GOOD.

B All leadwork to be carried out in accordance with the appropriate Lead Sheet Manual of the Lead Sheet Association, unless otherwise specified, and the English Heritage and Lead Sheet Association advisory note ‘Lead roofs on historic buildings.

C To minimise the risk of unqualified and/or poor workmanship all leadwork is to be physically carried out by the workforce of the member of the Lead Contractors Association. Under no circumstances is any leadwork to be carried out by a sub-contracted workforce.

D Ensure all surfaces to receive leadwork are fully prepared and are clean, dry and smooth with the abutting edges of boards planed level and nails and screws in boarding or rolls to be finished below the surface of the timber.

E Flashings and upstands are to be fixed in position by the lead contractor and pointed in by the Contractor using mortar to match the remaining pointing in colour, texture and workmanship.

F No flame producing apparatus is to be used unless prior approval has been obtained from the Historic Buildings Consultant.

G All hot work is to be carried out on strict adherence to the provisions of the HOT WORK PERMIT.

No flame producing apparatus is to be used unless prior approval has been obtained from the Historic Buildings Consultant.

H Where approved all lead-burning and use of flame producing apparatus is to be carried out at ground level at least 5 metres away from the building. All work is to be carried out in an area cordoned off and measures provided to protect and prevent damage to the grounds and any ornaments and features.

I All leadwork to comply with the guidelines of the Lead Sheet Association.

J Leadwork should comply with BS6915.

K Timbers immediately below leadwork are to remain untreated against timber decay and a chalk slurry is to be applied to the underside of leadwork in contact with any timbers.

L All nails and metal fixings to be non-ferrous.



2.2.20 Installation of rainwater goods

A Install pipework/gutters to replace the existing plastic/pvc sections and to ensure complete discharge of rainwater from the building without leaking.

B Preparing rainwater goods for painting

The surface preparation is vital for the long-term performance of the paint system and must be thoroughly undertaken to ensure any unsound paint and rust is removed.

Remove any oil or grease by thoroughly cleaning with warm water and detergent and rinsing with water. Rub down all surfaces to remove loose, perished and flaking paintwork. Tap or gently scrap any bubbles or irregularities to test the soundness of the metalwork beneath the paint finish. Carefully abrade any areas of rust or corrosion to remove loose deposits and feather into sound paintwork. Treat any areas of bare metal as soon as possible with 1 x coat of red lead primer, lapping at least 50 mm onto existing sound paintwork. Clean all surfaces with white spirit. Spot apply red lead putty to build up to even and level internal surfaces

C Fixing gutters

Set out to a true line and even gradient to ensure no ponding or back-fall.

Where possible the fall to be 1:600 (25 mm in 15m). The Historic Buildings Consultant to be advised where this cannot be achieved before further setting out of the falls.

Position outlets first, followed by the interlinking gutter section. Position outlets to align with connections to below ground drainage.

Provide 2 x brackets for each 6 foot length of gutter, with the brackets providing the optimum support to the joints. Additional brackets to be provided at angles and outlets.

Provide for thermal and building movement when fixing that can accommodate all movement in the structure and pipework. Ensure clearances are not reduced as fixing proceeds.

Gutter and fixings to be primed and undercoated before re-fixing.

D Fixing downpipes

Fix securely back to wall at 6 foot centres and plumb. Fixings to penetrate at least 50 mm into the wall using stainless steel fixings into mortar joints. Under no circumstances is any masonry to be drilled into or used for fixing.

Pipes to be left unsealed but wedged with lead slips against movement. Insert 25 mm wide lead slips down the gap between the outer face of the pipe and the inside of the face of the collar so they are not visible.

Pipes and pipe to be primed and undercoated before re-fixing.

E Painting and decorating of rainwater goods

Thoroughly prepare metalwork

For untreated galvanised surfaces, treat with 1 x coat etching primer prior to initial coats.

Apply 1 x coat primer sealer as initial coat.

Apply 1x full coat undercoat.

Apply 2 x full coats of exterior egg shell.

The interior of gutters to be applied with 2 x full coats of bitumen paint upon completion of application of undercoats.



2.2.21 Timber Repairs

The timbers should be band sawn or planed finish. They should not be artificially distressed.

The timbers should be of a similar section to the existing and shaped to follow the contour where spliced to existing timbers.

Existing timber that is to be repaired is to be cut back to a sound face which will accept the repair

All joints to be accurately cut with no gaps. There should be continuous contact across the joint faces.

No glue should be used in areas where moist conditions will exist.

The whole of the carpentry work is to be framed and pinned in the best possible manner with properly formed joints and fitted with all necessary ties, straps, connectors, bolts, screw, washers etc. as required. All ferrous straps/brackets to be primed and painted prior to fitting.

2.2.21 Epoxy resin repairs

A Epoxy resin for timber repairs to be:

West System’ (Epoxy 105 and slow hardener 206). To be used in accordance with the manufacturer’s instructions. Available from www.axminster.co.uk

B Rotafix P12 Primer and RM20 LW Repair Mortar. Available from rotafix: http://rotafix.co.uk

Each repair is to be individually designed to reflect the condition, extent and nature of decay and the characteristics and the structural performance of each individual timber. The Historic Buildings Consultant is to expressly confirm the repair methodology for each individual timber prior to works commencing.

C Timber

o Carefully select the timber to be used for the repair.

o Ensure that it has a similar moisture content to the timber being repaired [the host timber].

o Ensure that it is converted in a manner, as close as possible, to the quarter to maximise strength.

D The use of resin

o All epoxy resin repairs to use the ‘West System’ (Epoxy 105 and slow hardener 206) in accordance with the manufacturer’s instructions. This is used for its qualities as a gap filling adhesive.

o Epoxy resin repairs to only be carried out under the strict supervision of the Historic Buildings Consultant.

o The resin to be mixed in 5 x parts resin : 1 x part hardener with 20 % MEK spirit

o All rotten and/or loose timber to be consolidated with MEK spirit and sawdust before repair.

o Allow 7 x days for consolidation to set before implementing any further repairs.

o To remove any staining from surfaces of timbers that will be visible use Nicomors with a wire brush, under no circumstances is methylated spirits to be used.

o Do not work or plane the surfaces of the timbers to be jointed together, as this will reduce the surface area and texture more appropriate for a good key between the timbers.



E Resin and mild steel bars

o The mild steel threaded bars (minimum diameter 15 mm) to be sealed in a set resin prior to insertion into the repair (to protect against the tannin in the oak and provide surface friction to assist in the bonding).

o Carefully drill a hole through the new and existing timber to accommodate the mild steel threaded bar and resin.

o Drill with an auger into the upper face, or face of the timber that will be concealed, a weep hole for the resin. The weep hole will provide assurance that the resin has filled the drilled hole for the mild steel threaded bar.

o Insert the mild steel threaded bar.

o Where there is sufficient leeway between the two surfaces of the timbers apply a bead of resin to the existing timber a minimum of 30 mm from the external surface before placing the two faces of the timbers together.

o Push the two faces of the timbers together to provide a seal of resin – this will also assist in preventing the leakage of resin poured through the drilled hole for the mild steel bar.

o Carefully pour the resin in the holes until it appears out of the weep hole.

o Keep all support and form work in place until confident that the resin has completely set.

o The resin to be cleaned with Nicomors where it spoils the surface.

F Resin and oak repairs

o The aim of this repair is to reinstate the structural performance of the timber whilst still retaining as much of the decayed/host timber as possible, in particular the weathered and decayed faces and any surviving archaeological evidence [mortices, carpenter’s marks, graffiti etc].

o Consolidate the face of the timbers, as deemed appropriate by the Historic Buildings Consultant, using low viscosity epoxy resin.

o Cut the ‘host’ timber to accommodate the inserted new timber, wherever possible forming a wedge into the host timber.

o Wherever possible the host timber to be cut on one face [concealed outer or lower face] so that the inserted timber repair can be provided with minimal loss and/or intervention of the host timber.

o Where insertion of the repair timber from one face is not practicably possible the wedge to be cut to the full depth of the host timber.

o Remove the wedge cut from the face timber and put aside.

o Prepare the new insert to give a loose push fit.

o Prime the insert and the inner faces of the host timber, and apply epoxy resin as a gap-filling adhesive.

o Push in the insert timber, and clamp up the repair.

o The faces of the removed wedge are to be carefully removed, to a depth of approx. 20 mm. Using the epoxy as a gap-filling adhesive apply the faces back in their original position to the face of the inserted repair timber.

G Face patch repairs

To be achieved by using kiln dried heartwood of oak [unless specifically specified otherwise] and epoxy resin as a gap filling adhesive. The oak face patches to be secured to the host timber with oak pelleted M12 galvanised coach screws min. spacing at 300 mm.



2.2.22 Floorboard Repairs – lifting and removing floorboards

A To be achieved by using kiln dried heartwood of oak [unless specifically specified otherwise] and epoxy resin as a gap filling adhesive. The oak face patches to be secured to the host timber with oak pelleted M12 galvanised coach screws min. spacing at 300 mm.

B Where a floorboard is identified for lifting, to facilitate work, or removal express permission is to be obtained from the Historic Buildings Consultant before removing the floorboard[s] in question.

C The Contractor is to advise the Historic Buildings Consultant of the method for the removal of floorboards before removing the floorboard[s] in question.

D Where instructed by the Historic Buildings Consultant the floorboards are to be labelled and recorded in-situ, to a sufficient level of information to enable each floorboard to be reinstated in its original location and orientation.

2.2.23 Wood-fibre insulating boards – delivery, storage and site handling

A Take care with the storage and handling of the boards to prevent damage.

B Store the rolls of tape in a dry environment, as they need to be applied dry.

C Develop a site specific working methodology for handling the boards; two people will be required to handle and fix large boards.

D The size of the boards necessitates that the safe handling of the boards from the storage area to the working area on the access scaffolding is carefully planned and coordinated.

E Provide a secure workbench of sufficient size on the access scaffolding to facilitate the cutting and adjustment of boards.

F Boards should be cut using either Pavatex knife edge jigsaw blades (part no. PAVZK) or by a wavy edge insulation knife or by circular saw with a fine toothed tungsten carbide tipped blade.

G Wear safety goggles and dust masks during cutting to protect the user from small dust particles.

H Detailed installation procedures, including diagrams, are available from NBT at www.natural-building.co.uk.



2.2.24 Installing wood-fibre insulating sarking boards

A Methodology

Complete all repairs to timber roof structure.

Identify the first slope where the insulating sarking boards are to be laid.

For roof pitches >20°, boards are laid dry, i.e. no gluing is required.

Provide for adequate standing platforms for the safe handling and fixing of the first courses of boards.

Support each board by at least two rafters (spaced at a maximum of 790mm) at all times.

Lay boards in horizontal courses starting at the bottom of the slope and working up the slope. The longest side of the board to be laid parallel with the eaves/parapet gutter.

Place first course of boards with the groove at the base and tongue on the upper edge for the next course of board to be slid down onto. Temporarily secure boards with one fixing per rafter.

Allow for the offering of each board into place at least once, its removal to the work bench for cutting/slicing and re-offering to check fit. For a roof with undulation or complex structure with a number of different slopes, this may require several attempts to get the necessary shape and fit.

B Technique for laying boards

The cutting of boards to the angle of the edges of the roof slope will produce a lot of cut-offs, with approximately 50% of the board waste material. Allow for wastage when ordering the boards.

Starting with first roof slope, measure length of roof for the bottom course of boards to gauge the approximate number and sizes of the boards to avoid narrow boards at the margins. The strength achieved by the tongue and grooved joints allows for the jointing of the boards to be independent of the rafters.

Start from the edge of a roof slope, either a return or a valley.

Measure the length and the angle of any junctions of the board and roughly cut the board to shape to the proposed location on the roof slope.

In early stages of the operation it is beneficial for the boards to be cut oversized for their position, as this leaves sufficient material for subsequent cutting to achieve tight fit.

Offer board into proposed location on roof slope, measure and mark board to profile. If necessary, remove board and place on work bench, to cut and scribe to required profile.



Re-offer board into proposed location on the roof slope; re-check shape of board against proposed location on the roof.

Once the board forms tight fit in position, lay and move on to adjacent board in that horizontal course.

If the board does not form a tight fit, repeat the process. Measure and mark where the board is to be cut or scribed. Remove the board from the roof slope and cut and scribe to the required profile on the work bench.

Continue the process until the board forms a tight fit.

At valley gutters shape the board to push into the valley as far as possible. This is important to attain the best achievable seating for scribing of the boards on the secondary return slope. The boards of the secondary return slope to butt over the boards of the main slope.

Continue until the first horizontal course of boards on the roof slope is laid in position.

Proceed to lay second horizontal course of boards, working up the roof slope.

Stagger joints of boards from the course below.

To protect the tongue on the upper edge of the boards lay ladders on the surface of the boards to gain access to the roof slope above, from third course and above boards.

Allow for a 150mm oversail at the ridge for the top course of boards.

Complete one roof slope before proceeding to return/abutting roof slopes.

To achieve a tight joint at a ridge, on the last course of the secondary return slope, measure the length of each rafter from the top of the board of the course below to the underside of the top course board on the main slope. Transfer the information onto the board and draw a line across the top of the rafter markings to reproduce the line of the ridge on the board. Cut the board and offer into position to check it forms a tight joint.

Cut off excessive material of board to primary slope at ridges to form continuous surface with sloping face of board on secondary slope.

Seal around pipework running through the insulating sarking boards with Zero Ozone Depletion Potential (ZODP) expanding polyurethane foam.



C Undulations in roof structure

To accommodate the undulations of a roof structure, offer the board into place and mark the centre of the rafters. Remove the board to the work bench and slice the underside of the board with 15mm deep grooves on the vertical line of the rafter. Grooves to be incised into the board to form a series of slices parallel to the rafter. This enables the board to be moulded over the rafter and to take up the undulations of the surface of the roof, allowing the new roof covering to replicate that of the previous roof covering.

Secure pinning down of the boards to the rafters is essential to achieve tight jointing of the boards, particularly at abutment of slopes. This is important in achieving improved air-tightness.

Temporarily secure boards in the shaped position. Mark the centre of the rafters below on the upper surface of the board to provide a fixing guide. Secure board to each rafter in at least one place along length beneath the board with a short length of batten (off-cuts are suitable). Drill through batten and board into rafter, fasten with temporary washer and 150mm hexagonal head screw bolt. Leaving the boards securely pinned down with temporary fixings whilst the rest of the insulating sarking boards are installed, means by the time the temporary fixings are removed, the boards are permanently moulded into this shape.

Pin down all boards that required ‘shaping’ on a slope before proceeding to the next roof slope. This tight pinning down of boards on the primary slope at valley gutters and ridges is essential for scribing of boards on secondary return slope.

D Abutments with masonry

Where insulating sarking boards will be in contact with masonry, i.e. solid external, parapet and gable walls and chimney breasts the abutting ends of the boards need to be protected from potential damp. This can be achieved by over-lapping and securing of a damp-proof membrane:

Cut board to allow gap of 10mm between the board and the masonry

Provide a layer compressed foam to the upper surface of the last rafter to form a seal between the rafter and the underside of the board.

Lay damp-proof membrane to underside of board to project slightly beyond first rafter and secure with staples fastened to rafter and lagging.

Wrap the damp-proof membrane around the edge of the board and extended over the top face further than the first rafter.

Fill the gap between the damp-proof membrane and the brickwork with well-haired lime mortar.



E Sealing boards and laying roofing felt

Remove temporary battens from first slope.

Apply recommended tape over board joints at valleys, ridges, around chimneys or where tongue and groove joints have been broken.

Ensure all joints between the boards are dry and clean.

Apply recommended tape primer with a brush or roller to the boards and abutment surfaces and allow to dry for appropriate period in accordance with manufacturer’s recommendations (which is typically is reliant upon air temperature) prior to fixing the tape.

Roll the tape. Remove backing paper. Keep rolling tape continuously and press with other hand. Stretch tape to avoid creases. Press tape on firmly using a seam roller.

Lay roofing felt/underlay horizontally from bottom working up the slope. Mark centres of rafters on felt and secure felt with staples. If necessary, use temporary counter-battens to hold down the felt.

At valley gutters/returns/ridges, lap roofing felt/underlay by min. of 200 mm on both sides, to provide two courses of felt in the valley/over the ridge.

Upon completion of the fitting of the roofing felt/underlay allow for works to cease on the roof for one day to allow a fan pressure test to be carried out to determine the air-tightness of the sarking boarding.

The Site Foreman and two members of the Workforce involved with fitting the insulating sarking board to be in attendance during the fan pressure test. The purpose of the test is to identify areas where improved detailing is needed to attain improved air-tightness of the insulating sarking board.

Undertake remedial works to address areas identified where air leakage is occurring.

Remove the temporary counter-battens, secure roofing felt with permanent counter-battens.

Counter-battens should be 38mm x 75mm located above the rafters. Fix directly through counter-battens and Pavatherm Plus into rafter using four fasteners per linear meter of rafter.

The boards to be secured with stainless fixings at 600 mm centres. The length dependent on thickness of sarking board and quality of timber, a minimum depth into good sound timber should be 50 mm. It is essential that the fixings are provided with stainless steel ‘penny washers’ to prevent the fixings pulling through the boards.

Fix battens and roof coverings in conventional manner.



2.2.25 Installing breather paper

A Handle carefully to prevent tears and punctures and repair with adhesive tape any which do occur. If tear occurs, the batten above should be lifted, cut new section of underlay, remove torn section by cutting close to sides of rafters, slide up new section of underlay, staple sides to rafters and finally nail down batten above.

B Above roof insulation lay as the work proceeds ensuring continuity. Lay the underlay horizontally across the rafters, parallel to eaves, starting at the eaves and working to the ridge maintaining consistent tautness. The green side needs to be uppermost, the white side to the underside.

C The minimum horizontal laps are to be 100 mm. Vertical laps should be at least 100 mm wide and above a rafter position. The edge distance to the fixings should be at least 50 mm.

The underlay to both slopes to overlap the apex/ridge of the roof by a minimum of 150 mm.

Lap sides and ends of sheets not less than 150mm to shed water away from insulation.

At abutments (chimneys, walls etc.) the underlay to be turned up against the wall by a minimum of 100 mm.

Ensure that bottom edges overlap flashings, gutters, sills, etc. to allow free drainage to the exterior.

D To maximise air-tightness all joints/laps are to be taped and vertical laps are to overlap below a counter-batten.

E Where Roofshield is used as a ‘breather paper’ to walls the green side needs to be facing outwards/externally and the white side facing internally.

F Secure in place with counter-battens using 115 mm long Helifix InSkew 600 fixings.

2.2.26 Roof tiling

A 38 mm x 25 mm battens laid to 95 mm (3¾ inch) gauge secured with galvanised 60 mm nails at every counter-batten.

B 265 mm (10½ inch) x 165 mm (6½ inch) nibbed handmade clay tiles to be hung with a 76 mm (3 inch) lap using 38mm copper nails. Every fifth course of tiles to be double-nailed.

C Tile-and-a-half to be used at all abutments and at all cuttings against hips, valleys or verges.

D Verges, ridges and bonnet tiles to be bedded using moderately hydraulic lime mortar mix.

2.2.27 Stone roof slating

To be laid and/or repaired in accordance with the guidance of English Heritage [now Historic England] and the Stone Roofing Association [2009] in the Horsham Stone Roofing document.

http://www.stoneroof.org.uk/Horsham%20guide%20v2.pdf

The Historic Buildings Consultant to confirm methods of laying; double-lap or single lap systems.



2.2.28 Wattle and daub

A Wattles

Creating a panel to apply the daub to with riven oak staves and hazel wattles woven between

the staves. Where present holes and/or grooves for wattles and staves to be used, where holes

and/or grooves are absent or cannot be reinstated because of alterations the timber-frame to be

counter battened with heartwood of oak fixed to the timber-frame for the fixing of riven oak

laths.

B Application of earth daub

o Thoroughly mix the earth mix with a minimum amount of water being added to the mix.

o Add sufficient clean straw to achieve a good bind. o Achieve a good ‘plastic’ mix that is firm yet when held in the hand it can be squeezed

between the fingers when a fist is formed. o Apply the mix to the substrate or laths in workable handfuls building up the layers

ensuring that the mix is well compacted and pressed into position. o Avoid applying the mix in deep layers. o The panels to be allowed to dry out as slow as possible. Pay particular attention to the

edges of the panels that will be prone to rapid drying out. Gently extend the earth at the edges during drying out. Gaps that will inevitably occur between at the edges are to be wetted down and packed with an earth mix that is as dry yet as workable as possible.

o Cover the panels, if possible on both sides, with hessian and keep damp. o At the end of every day check the panels for cracks. o During the initial stages of drying only gently rework cracks whilst the mix is still

flexible enough to be attended to with the fingers.

C Preparation of daub for plastering and/or limewashing

o Carefully brushing down all loose surfaces with a soft brush. o Gently spraying the daub with a fine mist to wet down the daub in

preparation for the application of a single coat of lime putty limewash. o Gently applying a single coat of lime putty limewash. Allow the limewash to

carbonate before carrying out any further work to the infill panel. o Providing a mechanical fixing/key for the dubbing-out and render by

carefully pre-drilling the daub at angles and driving hazel spars into the daub. Alternatively, where appropriate, mechanical fixings to be provided with the careful insertion of pre-drilled brass screws, with brass gauzed heads, into the wattles.

o Carefully dubbing-out all deep recesses and voids with well-haired lime putty coarse stuff. Firmly compressing the coarse stuff, which is not to be applied in layers greater than 15 mm deep.

o Repeat the gentle spraying of the infill panel with a fine mist to wet down the daub and dubbing-out in preparation for the application of the second coat of lime putty limewash.

o Gently applying a second coat of lime putty limewash. This is to be applied immediately prior to the application of the new render, so that the render is applied onto ‘fresh’ limewash.

D Packing out of gaps

Pack out cracks and gaps between the existing infill panels and the timber frame using cut hand made clay tiles and/or well haired lime mortar.

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