Celotex Tuff-R CW4000

These boards are aimed specifically at offering cavity wall applications and is reinforced with glass fibres.  These products feature pure aluminium facers and the best reaction-to-fire performance (Euroclass D/S2/d0), measured in accordance with new European Standards, of any similar product on the market.

These boards are available from just insulation in the following thicknesses 35mm, 40mm, and 50mm with a standard board size of 1200 x 450 mm.

Description

Celotex tuff-R Zero CW4000 Cavity Wall Insulation Boards comprise a rigid polyisocyanurate-modified polyurethane foam core with a foil facing on both sides.

The boards have the characteristics of length (mm) 1200 x width (mm) 450 with a plain edge profile.

Thicknesses over 35 mm the foam core is reinforced with glass fibre.

Only insulation retaining fixings approved by the BBA should be used with the boards. The names and addresses of suppliers of approved fixings are available from Celotex and the BBA.

It should be noted that whilst approved ties are suitable for use for insulation retaining purposes, additional vertical twist ties to BS 1243 : 1978 may be required for structural stability in accordance with BS 5628-3 : 2001 where the overall cavity width exceeds 75 mm.

Design Data

General

Celotex tuff-R Zero CW4000 Cavity Wall Insulation Boards are effective in reducing the U value (thermal transmittance) of new external cavity walls with masonry inner and outer leaves (masonry includes clay and calcium silicate bricks, concrete blocks, natural and reconstituted stone blocks). It is essential that such walls are designed and constructed to incorporate the normal precautions to prevent moisture penetration.

Buildings subject to national Building Regulations should be constructed in accordance with the relevant recommendations of:

BS 5628-3 : 2001. In particular, Clause 5.5.2 of the Code of Practice Rain penetration should be followed in that the designer should select a construction appropriate to the local wind-driven rain index paying due regard to the design detailing, workmanship and materials to be used. BS 8000-3 : 2001.

Other buildings not subject to these Regulations should also be built in accordance with the Standards given in section 7.2 of this Certificate.

As with all cavity wall insulation, the construction and detailing should comply with good practice as described in the BBA joint publication Cavity Insulation of Masonry Walls €” Dampness Risks and How to Minimise Them. They are particularly important in areas subject to severe or very severe driving rain.

The use of cavity battens and/or boards during construction is strongly recommended to prevent bridging by mortar droppings. As with any other form of cavity wall insulation, where buildings need to comply with NHBC Standards or Zurich Building Guarantees Technical Standards, specifiers should observe the requirements of these documents.

Buildings up to and including 12 metres high

Where a residual cavity width of 50 mm or greater is specified the product can be used in any exposure zone. However, the use of the boards does not preclude the need to apply any external render coat or other suitable finish in severe exposure zones where such application would be normal practice.

The minimum residual cavity width to be maintained during construction must be 25 mm. To achieve this requirement a greater nominal residual cavity width may need to be specified at the design stage to allow for inaccuracies inherent in the building process. The specifier may either ...

design a cavity width by consideration of the dimensional tolerances of the components which make up the wall by reference to the British Standards relating to the bricks, blocks and boards, or use the data from their respective manufacturers. In addition, allowance may need to be made for the quality of available building operatives and the degree of site supervision or control available,

or

design a nominal residual cavity width of 50 mm (a residual cavity nominally 50 mm wide will be required by the NHBC, where normal standards of tolerance and workmanship are adopted).

The size of residual cavity obtained in the processes described in section 7.8 of this Certificate is also subject to the following limitations in respect of exposure of the proposed building as set out in the table below ...

Maximum allowable total exposure factors of different constructions (1)
Construction	Maximum allowable exposure factor E
All external masonry walls protected by rendering (to BS 5262 : 1991) tile hanging, slate hanging, timber, plastic or metal weatherboarding or cladding	no restriction
One or more external masonry walls constructed from facing clay brickwork or natural stone, the porosity of which exceeds 20% by volume. Mortar joints must be flush pointed or weatherstruck	100
One or more external masonry walls constructed from calcium silicate bricks, concrete blocks, reconstituted stone or natural stone, the porosity of which is less than 20% by volume, or any material with raked mortar joints	88
(1) Based upon the approach in BS 5618 : 1985.

 

The width of residual clear cavity to be achieved is to be a minimum of 50 mm, and the following requirements apply:

from ground level the maximum height of continuous cavity walls must not exceed 12 metres; above 12 metres the maximum height of continuous cavity walls must not exceed 7 metres

the specifier must take care when detailing to ensure that the introduction of the insulation does not affect the weather resistance of the wall. More than average site supervision is recommended during the installation of the product

the exposure factor does not exceed 120

where, for structural reasons, the cavity width is reduced, eg by the intrusion of ring beams, a minimum residual cavity width of 25 mm must be maintained and extra care must be taken with fixings and weatherproofing, eg inclusion of a cavity tray.

Thermal insulation

For the purpose of U value calculations to determine if the requirements of the Building (or other statutory) Regulations are met, the thermal conductivity (90/90 lamba value) of the boards may be taken as declared within the Celotex BBA Certificate No. 95/3197 -

CW4000 = 0.023 Wm1K 1

The requirement for limiting the heat loss through the building fabric will be satisfied if the U values of the building elements, including thermal bridging, do not exceed the maximum values in the relevant Elemental Method given in the national Building Regulations thus: England and Wales - Approved Documents L1 and L2, Table 1 Scotland - Technical Standards J3.2, Table 1, and J8.3, Table Northern Ireland - Technical Booklet F, Tables 1.2 and 1.4.

Where Celotex Tuff-R Zero CW4000 should be used

Use Celotex tuff-R„¢ CW4000 high performance thermal insulation in cavity wall applications to minimise insulation thickness and give the following benefits:

Easy to fit between wall ties using cavity tie clips for retention

Provides reliable long term energy savings for buildings

Low emissivity foil facers give improved thermal insulation with cavity air spaces

Excellent dimensional stability  Conveniently sized boards for installation between cavity wall ties

Easy to cut boards to fit

Installation guidelines for internal lining systems

Ensure that existing walls are permeable. Strip any gloss paint or vinyl wallpaper.

Cut the 1200 x 2400 mm Celotex tuff-R„¢ GA4000 boards to fi t the fl oor-to-ceiling height of the room.

For optimum thermal performance, the unprinted foil surface should face the batten cavity.

Fix horizontal battens over the insulation at the top and bottom of the wall to hold the boards in place.

Seal all board joints to create a vapour control layer using an aluminium foil self-adhesive tape.

Add further vertical battens over the insulation at appropriate spacing to provide adequate fixings for the selected lining system. Ensure that a batten coincides with each lining board joint.

Apply an appropriate sealant around the perimeter of the insulation to provide a vapour seal.

Additional battens are required around all openings to provide fi xings for linings and grounds for skirtings, etc. Battens should be minimum 50 x 25 mm treated softwood.

The batten depth must be increased to take account of the conduit, if cabling is to be located within the cavity created by the battens.

Use independent horizontal battens for heavy wall-mounted components. Longer fi xings may be necessary to fi x heavy items to the masonry, independently of the battens.

Line window and door reveals with thinner Celotex T-Break TB4000 boards to reduce the risk of thermal bridging. Fix a batten around the edge of the opening and scribe the board to fit the reveal. Cut the dry lining to suit and mechanically fix into the masonry reveal using proprietary fixings. Finish using an angle fillet at the frame and an angle bead or scrim tape at external corners.

Installation guidelines for external render systems

 Prior to the installation of the Celotex insulation boards, the substrate must be checked for soundness.

 Large uneven projections should be removed and all holes filled and levelled. Loose material should be cleaned off to leave a sound dry surface.

Downpipes should be temporarily removed and if necessary, relocated after completion of installation. Lengthening of overflow pipes should be allowed for, together with extensions to sills.

A starter strip/drip should be located at least one half brick above the dpc and fixed directly to the substrate with plugs and screws.

For optimum thermal performance, the unprinted foil surface should face the batten cavity.

The Celotex insulation should be fixed to the substrate using proprietary fasteners, which are driven into pre-drilled holes.

All insulation board joints should be tightly butted and end joints staggered.

Apply preservative-treated timber battens vertically over the face of the insulation, secured back to the underlying masonry.

Fix a breather membrane horizontally to the faces of the battens with minimum 100mm laps.

Render finish

Fix stainless steel expanded metal lathing to the battens. Proprietary systems are available with reinforcing ribs to allow for a full span of 600 mm between battens. The render system should then be applied in accordance with the manufacturer's guide lines.

Tile hanging

Tilting fi llets should be applied at horizontal junctions to suit the design requirements. Fix tile battens to vertical battens to suit the tile gauge. Apply vertical damp proof membranes at all junctions, and hang tiles in accordance with the manufacturer's instructions.

Other cladding

Timber or other lightweight cladding systems can be fixed to the vertical battens.

Manufacturer's details

Celotex Limited, Lady Lane Industrial Estate, Hadleigh, Ipswich, Suffolk, IP7 6BA

Web site: Celotex Home Page

Web site: Celotex U-value Calclator

Celotex Technical Advisory Service

While just-insulation provides the very best products at the very best prices ...
For the very best advise we recommend you contact the Celotex Technical Advisory Service.
Tel: 0901 996 0100 (30p per minute) Fax: 01473 820 889 Email: technical@celotex.co.uk

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