Return Delivery Logo
0207 112 8999 Return Home Logo Return Home Logo
Home Support

Search Product

Enter keyword


Your basket is empty.
Visit the store to add products to your basket.

Valid HTML 4.01 Transitional

Celotex Thermal Insualtion Boards - Delivered to your door - Free*

For Specific Celotex applications see Floors, Walls and Roofs

At Planet Insulation we supply the whole Celotex range, Celotex GA4000 range, Celotex PL range a plasterboard backed product, Celotex FF range specifically for under floor heating, Celotex cavity wall insulation as well as Celotex TD boards for flat roofs. Celotex insulation boards are the ideal product whatever you home insulation needs are. To buy click here Celotex GA4000 range boards , Celotex PL4000 range, Celotex FF4000 range

The unique Celotex online U-value calculator generates a U-value specific to the chosen construction and enables you to input a range of different construction parameters to evaluate their impact on thermal performance.

The Celotex range has applications in Floors, Walls and Roofs

AND FINALY please don't forget every time you use a debit card with us we make a donation to charity.

Please see instructional Celotex Videos below



* This is the maximum discount achievable if you buy in bulk. Discounts calculated automatically.
Click on any underlined product name to link to a full product detail page.
Product Name Size Unit Price Multi-Buy Price* Qty. SubTotal Final Price Ex VAT Discount %
 Celotex 12mm Foil Backed PIR Boards TB4012 ( Enquire about availability before ordering) 2400mm*1200mm £10.40 £10.40 
£0.00 £0.00 0.00 %
 Celotex 25mm Foil Backed PIR Boards TB4025 2400mm*1200mm £12.80 £12.42 
£0.00 £0.00 0.00 %
 Celotex 30mm Foil Backed PIR Boards TB4030 2400mm*1200mm £14.46 £14.03 
£0.00 £0.00 0.00 %
 Celotex 40mm Foil Backed PIR Boards TB4040 2400mm*1200mm £18.45 £17.90 
£0.00 £0.00 0.00 %
 Celotex 50mm Foil Backed PIR Boards GA4050 2400mm*1200mm £20.15 £19.55 
£0.00 £0.00 0.00 %
 Celotex 60mm Foil Backed PIR Boards GA4060 2400mm*1200mm £24.56 £23.82 
£0.00 £0.00 0.00 %
 Celotex 70mm Foil Backed PIR Boards GA4070 2400mm*1200mm £28.80 £27.94 
£0.00 £0.00 0.00 %
 Celotex 75mm Foil Backed PIR Boards GA4075 2400mm*1200mm £29.76 £28.87 
£0.00 £0.00 0.00 %
 Celotex 80mm Foil Backed PIR Boards GA4080 2400mm*1200mm £31.88 £30.92 
£0.00 £0.00 0.00 %
 Celotex 90mm Foil Backed PIR Boards GA4090 2400mm*1200mm £35.59 £34.52 
£0.00 £0.00 0.00 %
 Celotex 100mm Foil Backed PIR Boards GA4100 2400mm*1200mm £36.18 £34.99 
£0.00 £0.00 0.00 %
 Celotex 120mm Foil Backed PIR Boards XR4120 2400mm*1200mm £43.58 £42.27 
£0.00 £0.00 0.00 %
 Celotex 130mm Foil Backed PIR Boards XR4130 2400mm*1200mm £48.75 £47.29 
£0.00 £0.00 0.00 %
 Celotex 140mm Foil Backed PIR Boards XR4140 2400mm*1200mm £51.67 £50.12 
£0.00 £0.00 0.00 %
 Celotex 150mm Foil Backed PIR Boards XR4150 2400mm*1200mm £51.59 £50.04 
£0.00 £0.00 0.00 %
Polythene Damp proof membrane (black) 4m x 25m 250Mu 4 metres x 25metres £35.05 £35.05 
£0.00 £0.00 0.00 %
Polythene Damp proof membrane (black) 4m x 25m 300Mu 4 metres x 25metres £39.75 £39.75 
£0.00 £0.00 0.00 %
Foil backed Jointing Tape 50mm *45m 50mm*45m £6.42 £5.78 
£0.00 £0.00 0.00 %
Foil backed Jointing Tape 75mm *45m 75mm*45m £7.55 £6.80 
£0.00 £0.00 0.00 %
Foil backed Jointing Tape 100mm *45m 100mm*45m £9.27 £8.34 
£0.00 £0.00 0.00 %
We Supply Celotex TB4000, GA400, Celotex Pl4000, and Celotex GA range Celotex FF4000  

Product Summary

Celotex TB4020 - XR4000 (previously TB3000- XR3000) is specifically designed for "cut-to-fit" applications between rafters or joists, enabling the achievement of lower U-values with a single layer of insulation than has previously been possible.

XR4000 is entirely appropriate for use in roofs, ceilings, walls, and floors.

These boards are silver backed both sides easy to cut with a blade or fine toothed saw. They are ideal for insulating walls concrete or timber floors as well as timber or steel framed walls.

Product Description

Like Celotex Tuff-R Zero GA4000, the XR4000 range is installed in conjunction with an appropriate lining panel, for example standard gypsum plasterboard to BS 1230-1 : 1985.

Celotex Xtra-R is a premium performance multi-purpose rigid polyisocyanurate foam (PIR) thermal insulation board with reflective foil facings. provides multi-purpose cavity wall insulation boards that are uniquely reinforced with glass-fibre and feature the best reaction-to-fire performance measured in accordance with new European Standards of any PUR / PIR.

Product Application


Technical Spec

Product Code

Thickness (mm)

R-value (m2K/W)

U-Value (W/m²K)

Weight (kg/m2)

Board weight (kg)

Celotex XR4000






Celotex XR4000






Celotex XR4000






Celotex XR4000






Celotex XR4000






Celotex XR4000






Celotex XR4000






Thermal conductivity / Lambda Value (W/mK) = 0.022: Compressive strength (kPa) = ≥ 120: 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.


Where Celotex Extra-R XR4000 should be used

This thicker version can be used in any rafter or joist application where there is the need to achieve improved u-Values from those available from a thinner board.

Celotex Extra-R XR4000 between rafters Insulation between rafters:

Celotex XR3000 between rafters

Use Celotex Extra-R XR4000 high performance thermal insulation in pitched roofs either between and under rafter or between the rafter applications to minimise insulation thickness and give the following benefits ...

Ideal for use where headroom is limited

Provides reliable long term energy savings for buildings

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

Creates a warm habitable roof space

No need to insulate water pipes and tanks

Suitable for new build and major refurbishment projects

Minimised additional loading to the structure

Ideal for loft conversions/room in roof applications


The void created by a pitched roof can be made habitable by insulating along the plane of the roof pitch with Celotex rigid PIR insulation boards. This creates a warm, potentially habitable roof space in which water pipes and tanks no longer need to be insulated.

If BS 747: 2000 slater's felt is being used, a minimum 50 mm ventilated air space must be provided between the felt and the cold side of the insulation in order to minimise the risk of condensation formation. This construction is known as a ventilated construction.

With some breathable membranes, the cold side of the insulation may be placed in direct contact with the membrane (check with membrane supplier prior to specification). However, the outer side of the membrane must be adjacent to an air space to allow moisture vapour to escape to the outside of the building. This is known as an unventilated construction.

Insulation for timber frame wall lining:

Timber frame wall lining with Celotex Rxtra-R

Celotex Insulation for timber frame wall lining Celotex utilises the low lambda values of Celotex tuff R GA4000 and ExtraR XR4000 between the studs, followed by an internal lining of Celotex T-Break TB4000 over the studs, providing for a thin build-up with the excellent thermal insulation.


Offers the thinnest solution available Provides reliable long term energy savings for buildings
Low emissivity foil facers give improved thermal insulation with cavity air spaces Provides a vapour control layer when board joints are taped
Reduces thermal bridging through studs and rails
Can be nailed direct to stud framing
Dryline directly over insulation
Provides cavity for services Installation guidelines
Suspended timber floor insulation

Fixing floppy quilt insulation between floor joists can be difficult. Insulating a suspended timber floor is made easy using Celotex Insulation cut to fit between joists.

The specification of insulation for ground floors is more complex than that for walls or roofs. This is because the mechanisms for heat flow are affected by the ratio of surface area to perimeter.

With a suspended timber floor, there is little choice but to install the insulation between the joists, but the thermal bridges created by the joists have to be considered.

Continuity of the insulation must be ensured by packing the spaces between the external walls and the joists with insulation. The void below an insulated suspended timber floor must be well ventilated. The insulation must be cut to fit tightly between the joists to prevent heat loss.


Make sure all studs and rails are flush, with no projections, and that services are correctly installed.

Cut Celotex Extra-R XR4000 to fit tightly between all studs and rails.

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

Insert insulation into framing and push back to plywood sheathing.

Fit services in to cavity if required.

Measure the wall height from floor level to underside of ceiling joists and cut board length to suit, using a trimming knife.

Ensure that the wall insulation is continuous with the floor perimeter insulation.

Cut boards for infill panels, using off-cuts where possible, making sure there are no gaps at wall abutments.

Tightly butt edges of boards together, making sure there are no gaps.

Temporarily secure the boards with clout nails at 600 mm centres. Mark stud lines on board surface as fixing guides for dry lining.

Always fix back to solid timber, both at stud lines and at top and bottom rails.

Ensure that all board surfaces are clean and free from dust and then apply aluminum foil vapour-seal tape to all joints. Taping the joints of the Celotex insulation with self adhesive aluminum foil tape provides a good vapour control layer and improves air tightness.

Seal the insulation at all abutments and service penetrations with a vapour resistant sealant.

Fix plasterboard lining over the Celotex insulation using plasterboard nails or screws of appropriate length and joint or skim to the desired finish.

No separate vapour check membrane is required in this application; Celotex insulation acts as an effective internal vapour control layer when all joints are sealed. Suspended timber floor insulation Celotex



Return to products