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40mm Celotex TB4040 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
40mm Celotex TB4040 is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Celotex is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.
£21.75£26.10 Ex VATInc VAT£7.55£9.06 Per M2 Add to cart -
40mm Ecotherm Eco-Versal PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
40mm Ecotherm Eco-Versal is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Ecotherm Eco-Versal is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.
£21.97£26.36 Ex VATInc VAT£7.63£9.16 Per M2 Add to cart -
40mm Recticel Eurothane GP PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
40mm Recticel Eurothane GP is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Recticel is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.
£21.43£25.72 Ex VATInc VAT£7.44£8.93 Per M2 Add to cart -
40mm IKO Enertherm ALU PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
40mm IKO Enertherm ALU PIR (polyisocyanurate) insulation is a top-quality insulation board featuring a rigid PIR foam core and reflective aluminium foil facings. It delivers outstanding thermal performance and moisture resistance, making it suitable for various installations and an ideal choice for different energy-efficient projects.
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40mm Kingspan OPTIM-R Flooring Insulation Board
40mm Kingspan OPTIM-R Flooring Insulation Panels achieve a declared thermal conductivity of 0.007 W/m∙K.
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40mm Kingspan OPTIM-R Roofing Insulation Board
40mm Kingspan OPTIM-R Roofing Insulation Panels achieve a declared thermal conductivity of 0.007 W/m∙K.
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40mm Kingspan Therma TP10 / TF70 / TW55 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 8 (23.04m2)
All three models 40mm Kingspan Therma PIR Insulation Board:
- 40mm Thermapitch TP10
- 40mm Thermafloor TF70
- 40mm Thermawall TW55
share the same high-performance PIR core and low-emissivity foil facings, offering excellent thermal efficiency and easy installation. Although labeled differently, these boards share identical technical specifications.
Non-refundable.
£262.88£315.46 Ex VATInc VAT£11.41£13.69 Per M2 Add to cart -
40mm Mannok PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2
40mm Mannok PIR Insulation Board is an excellent choice for anyone looking for a high-performance insulation solution that provides superior thermal efficiency. It is ideal for use in any construction project, such as commercial and residential, in wall applications as well as roofing and flooring applications.
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40mm Rockwool RW3 Acoustic Insulation Slab 1200mm x 600mm 86.40m2 Pallet
40mm Rockwool RW3 Slabs can be applied to an array of general building applications for acoustic, thermal and fire protection of partition walls, ceilings, floors and roofs.
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40mm Rockwool RWA45 Acoustic Insulation Slab 1200 x 600mm 138.24m2 Pallet
40mm Rockwool RWA45 has been developed for thermal, acoustic and fire performance in a range of construction types. It is suitable for applications on partition walls, ceilings, floors and roofs.
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40mm Unilin Thin-R PIR Insulation Board 2400mm x 1200mm (8′ x 4′) Pallet of 56 (161.28m2)
40mm Unilin Thin-R PIR insulation is a foil faced, high-performance insulation solution that offers exceptional thermal efficiency and durability. This polyisocyanurate insulation board, formerly known as Xtratherm, is ideal for a range of applications, such as floors, pitched roofs, and walls.
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40mm Insulation Thermal
40mm insulation is a thin insulation layer used to improve thermal control in areas with limited space. It is often specified to address specific thermal detailing requirements rather than to meet whole-element U-value requirements on its own. It fine-tunes heat performance, reduces cold surfaces, and supports a wider build-up.
What is 40mm insulation thickness?
40mm insulation thickness means the material measures exactly 40 millimetres from the warm side to the cold side. The dimension matters because heat loss calculations depend on thickness and thermal conductivity, not just material type.
At this depth, insulation slows heat movement but does not stop it entirely. The actual performance depends heavily on the material’s thermal conductivity (lambda value). High-performance foam materials deliver greater resistance at 40mm than fibrous products.
This size is commonly used where adding more depth would interfere with fixings, floor heights, or detailing.
What is 40mm thick insulation used for?
40mm thick insulation is usually added to improve comfort and efficiency. In most cases, it does not meet UK Building Regulations on its own.
Typical applications include:
- Internal wall upgrades that aim to keep space loss minimal.
- Floors where height build-up is tightly controlled.
- Roof refurbishments where rafters cannot be deepened.
- Thermal breaks around steel, concrete, or structural junctions.
In many builds, thick 40mm insulation works as a supporting layer alongside thicker insulation elsewhere.
Types of insulation 40mm thick
There are several insulation types available at insulation 40mm thickness:
Rigid foam boards
- PIR Insulation: High thermal efficiency for its depth. Often chosen when maximum performance is needed in minimum space. Joints should be fully sealed to minimise air leakage.
- Phenolic Insulation: Offers slightly better thermal performance than PIR. More brittle, so best handled carefully.
- EPS Insulation: Lower performance but stable, lightweight, and cost-effective. Common under floors.
- XPS Insulation: Stronger and more moisture-resistant than EPS. Often used where compression or damp exposure is a concern.
EPS/XPS offers limited thermal benefits at 40mm thickness unless paired with thicker layers.
Mineral wool
- Glass mineral wool: Flexible and easy to fit. Thermal performance at this thickness is modest. Mainly used for sound control, not thermal protection.
- Rock mineral wool: Denser than glass wool. Offers better acoustic and fire performance.
Advanced products
- VIP (Vacuum Insulated Panels): Extremely high performance at very thin depths. Used only where space is critical, as they cannot be cut.
Some aerogel products are available at similar thin dimensions, though they are specialised and costly.
Need bulk insulation quantities or help choosing the right material? Get a fast quote from our team and secure the right 40mm solution for your build.
FAQ
Where to buy 40mm insulation?
You can buy insulation 40mm thick online from Insulation Wholesale. We stock a wide range of materials, so you can choose based on performance, space, and budget. We offer reliable lead times and support both trade and one-off projects. Our ordering process is straightforward, and we handle all bulk quantities properly.
How to fix 40mm insulation?
The fixing method depends on the material and surface:
- Rigid boards are usually bonded with adhesive, mechanically fixed, or both.
- Floors often rely on compression and perimeter restraint.
- Timber frames may use friction fit or fixings through battens.
The key rule is to ensure full contact with the surface or space. Gaps reduce performance more at thin depths than at thick ones.
How to cut 40mm insulation?
- Foam boards: Cut with a fine-tooth saw or insulation knife.
- Mineral wool: Cut a little oversized (so it friction-fits) with a long-blade knife.
- VIP panels: Do not cut – order exact sizes.
Measure accurately because a poor cut wastes more performance at 40mm than at larger thicknesses.
