Celotex XR4150 150mm
Celotex XR4150 150mm

Celotex Installation Video
Technical Information | |
Size | 2400mm*1200mm |
Thickness | 150mm |
Length | 2.4m |
Width | 1.2M |
Category | Celotex GA4000 range |
Volume discounts apply automatically.
Product Summary
Celotex XR4150 (previously 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.
XR4150 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.
Celotex Tuff-R, with its low emissivity foil facings, is ideal for pitched and flat roofs, solid masonry walls, timber or steel framed systems, and floors.
Celotex Tuff-R is a 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 (Rigid polyurethane / polyisocyanurate) product on the UK market
Technical Spec
Product Code | Thickness (mm) | R-value (m2K/W) | U-Value (W/m²K) | Weight (kg/m2) | Board weight (kg) |
Celotex XR4150 | 110 | 5.00 | 0.20 | 3.59 | 10.34 |
Celotex XR4150 | 120 | 5.45 | 0.18 | 3.89 | 11.20 |
Celotex XR4150 | 130 | 5.90 | 0.17 | 4.20 | 12.10 |
Celotex XR4150 | 140 | 6.35 | 0.16 | 4.50 | 12.96 |
Celotex XR4150 | 150 | 6.80 | 0.15 | 4.81 | 13.85 |
Celotex XR4150 | 165 | 7.50 | 0.13 | 5.43 | 15.64 |
Celotex XR4150 | 200 | 9.05 | 0.11 | 6.63 | 19.09 |
Thermal conductivity / Lambda Value (W/mK) = 0.022: Compresive strength (kPa) = ≥ 120: Water vapour restistance (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 Application
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 XR4150 between rafters Insulation between rafters:
Use Celotex Extra-R XR4150 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.
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.
Insulation for timber frame wall lining:
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.

Benefits:
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.
Installation Instructions
Make sure all studs and rails are flush, with no projections, and that services are correctly installed.Cut Celotex Extra-R XR4150 to fit tightly between all studs and rails.
For optimum thermal performance, the unprinted foil surface should face the air cavity.
For optimum thermal performance, the unprinted foil surface should face the air cavity.
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