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Celotex TD4000 Flat Roof - Plywood Bonded Boards

Celotex have replaced this range. Please consider - Celotex Crown-Fix

Also consider using alternative Rigid PIR Boards with external quality Plywood Boards added separately


Product Applications Celotex TD4000 Flat Roof Plywood Bonded Boards for light traffic Flat Roof applications.

Celotex TD4000 PIR Insulation for light traffic Flat Roof applications.

These boards offer a quick and easy way to achieve effective thermally insulated flat roof decks for building structures such as small extensions or garage roofs where there will only be occasional traffic.

Flat Roof Insulation Decks, Garage Conversions, Ventilated Lead Covering

Product Characteristics

Celotex TD4000 Tempchek incorporates a foil faced insulation board, to give the best insulation value bonded to a facing of 5.5mm exterior-grade ply.

Tempchek has a 5.5mm exterior grade plywood upper facing bonded to rigid polyisocyanurate foam (PIR) board, manufactured using zero ozone depletion potential blowing agents with low global warming potential.

Board size: 1200 x 2400mm, Thickness : 96-126mm (inc 5.5mm ply), Lambda: 0.021 W/mK, Low emissivity foil facers

Product Advantages

TD4000 is a three-in-one product to provide deck, vapour control layer and insulation

Warm roof construction due to over joist installation

Provides reliable long term energy savings for buildings

Ideal for use in occasionally trafficked applications

Rapidly installed and weatherproofed

Accepts a wide variety of weathering systems

Offers high performance insulation delivering better U-values and thinner solutions.

Provides warm roof construction due to over joist installation

Is rapidly installed and weatherproofed

Accepts a wide variety of weathering systems

Is ideal for use in occasionally trafficked applications

Has zero ozone depletion potential (zero ODP) and low global warming potential (GWP)

Future proofs the energy performance of new and existing buildings

Product Specifications

Celotex TA4000 Heavy Traffic Roof Insulation Boards

Product Code

Board dimensions

Thickness (mm)

λ Value (w/mK)

R-value (m²K/W)

U Value (W/m²K)

Weight (kg/m²)

Unit weight (kg)

Celotex TD4096 12 x 1.2 x 2.4 = 34.56m² 96 0.022 4.10 0.24 6.46 223.26
Celotex TD4106 11 x 1.2 x 2.4 = 31.68m² 106 0.022 4.55 0.22 6.97 220.81
Celotex TD4116 10 x 1.2 x 2.4 = 28.80m² 116 0.022 5.00 0.20 7.28 209.66
Celotex TD4126 9 x 1.2 x 2.4 = 25.92m² 126 0.022 5.45 0.18 7.58 196.47

Thermal conductivity / Lambda value (W/mK) = 0.022 | Compressive strength (kPa) = ≥ 140 | Water vapour resistance (MNs/g) = > 150 | Please Note: R-Value = Thermal Resistance; U Value = Thermal Transmittance Co-efficient; Compressive strength = kiloPascals; Vapour resistance = MegaNewton seconds per gram.

Product Information and Certification

Links to manufacturer's information. Click to download in a separate browser window.
Celotex TD4000 Datasheet | Built-up flat roofing using Celotex TD4000 | Celotex Flat Roof Deck Insulation | Celotex TD4000 CE Certification | Celotex Handy Guide

Alternative Products & Accessories

Flat Roof - Rigid PIR Boards

  • Celotex TA4000

    These boards for single-ply flat roofing applications where the higher compressive strength is a pre-requisite.

    Click for more information

    Celotex TA4000 boards for single-ply flat roofing applications where the higher compressive strength is a pre-requisite
  • Celotex TC3000

    Ideal for built-up flat roofing applications, involving hot applied bituminous and mastic asphalt water-proofing systems.

    Click for more information

    Celotex TC3000 for built-up flat roofing applications involving mastic asphalt water-proofing systems
  • Kingspan TR26

    ThermaRoof foil faced insulation for flat roofs with mechanically fixed single-ply waterproofing.


    Click for more information

    Kingspan ThermaRoof TR26 foil faced insulation for flat roofs with mechanically fixed single-ply waterproofing
  • Kingspan TR27

    Glass tissue faced insulation for fully adhered single-ply, partially bonded built-up felt, mastic asphalt waterproofing.

    Click for more information

    Kingspan TR27 glass tissue faced insulation for fully adhered single-ply partially bonded asphalt waterproofing

Product Installation

Celotex Tempchek TD4000 products should be installed in accordance with these instructions

Ensure that joist spacing is at no more than 600mm centres and that the dimension of the joist is sufficient to span and accept additional loads. If asphalt weathering is to be used, joists should be at no more than 400mm centres.

Install the insulation boards, ensuring that the long edges are parallel to the line of the joists. 50mm x 50mm cross noggings should be inserted between joists to support the short edges of the boards.

Where boards butt together, bed onto twin beads of vapour sealant wide enough to accommodate this arrangement. This completes the vapour control layer (VCL) when combined with each board’s foil facings.

Lay the boards with the plywood side uppermost and stagger board joints. Leave a gap of approximately 2mm between boards and ensure a minimum 20mm bearing on joists and noggings.

Fix Celotex TD4000 with corrosion-proof Suretwist Composite Panel helical fasteners at a frequency to suit the design wind load. Refer to BS 6399-2 Code of Practice for Wind Loads. As a guide, 16 fasteners per board will resist a wind load of 2.22 KN/m2 based on a design load of 0.4 KN per fastener.

Ensure that fixings are no less than 10mm in from the board edge or 50mm from each corner. They should be equally spaced along the supporting joists. Fixings should be long enough to penetrate at least 38mm into the supporting timber.

Stagger opposing fixings where two board edges share the same joist or noggin.

Provide a complete insulation envelope by extending the wall insulation board up to the underside of the roof deck.

Provide a soffit or ceiling below the joists, as the surface of the product is not designed to be used as a decorative internal finish.

Ensure that the plywood is completely dry before any weathering system is applied.

Always use a Type 3G felt to BS 747 as a vapour diffusion first layer when using BUR weathering systems. When using a single-ply membrane, additional 12mm plywood has to be applied on top of the Celotex TD4000.

Temporary protection must be provided for both the insulation and the waterproofing, if significant foot traffic is anticipated either during or after installation.


The structure should be designed so that the finished roof has a continuous, smooth and even slope towards the rainwater outlet or gutter. The minimum fall should be 1:80 to avoid ponding water.

Deck stability

Celotex TD4000 incorporates exterior grade WBP plywood to BS 1203, laminated to the surface. This gives the product excellent strength. Boards can span up to 600mm joist centres to provide a suitable substrate for a variety of weathering systems.

Vapour control layer

Celotex TD4000 has a built-in VCL due to the foil facers but this is discontinuous at the board joints. In some applications no further attention to moisture control may be necessary. Celotex would generally recommend the application of a vapour sealant between the tops of the boards at all edges. This is essential in areas of potentially high humidity.

Manufacturer's Contact Details

Celotex Limited

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

Celotex Technical Advisory Service.

Telephone: 0901 996 0100 (30p per minute) - Fax: 01473 820 889
Web sites: Celotex Home Page / Celotex U-Value Calculator.

Our Contact Details

Insulation Online Limited

Sales Office only:

39 Normandy Road, Worthing, West Sussex, BN14 7DX, UK

Telephone: 0333 9000 989