75mm Insulation Board CW4000
A 75mm insulation board is a rigid panel used to reduce heat transfer through a building. It is common on refurbishment jobs, extensions, and higher-performance assemblies in new builds.
What is 75mm insulation board?
A 75mm thick insulation board is a factory-manufactured rigid panel with a fixed insulation thickness running through it. This thickness is often specified when designers are targeting specific U-values rather than simply improving thermal comfort.
The average 75mm thick insulation board is made from rigid insulation foams (such as PIR or phenolic) or expanded polystyrene (EPS). Unlike rolls, it does not sag or slump over time. Once fixed in place, it remains dimensionally stable.
Most are manufactured in standard sizes such as 75mm insulation board 1200mmx2400mm, which makes setting out easier and reduces wastage.
What is 75mm thick insulation board used for?
A 75mm insulation thickness board is used in areas where heat loss is high and thinner insulation would fall short. It is mostly installed in:
- External wall systems and internal wall upgrades
- Pitched roofs between or below rafters, where permitted by the roof build-up design
- Flat roofs as part of a layered warm roof build-up
- Floors where headroom allows deeper insulation
75mm insulation is often specified to help meet Building Regulations requirements rather than simply improve comfort.
Types of insulation in 75mm thickness board
The three main insulation types available at this thickness are:
EPS Insulation (expanded polystyrene)
A cost-effective, lightweight option that is easy to cut. It insulates well but needs more thickness than other materials to achieve the same performance. However, it delivers consistent performance and has good moisture resistance when correctly specified and installed.
Phenolic Insulation foam board
Phenolic boards offer very high thermal resistance relative to thickness. That means you get strong performance without going thicker. However, phenolic board edges are fragile and need careful handling.
PIR Insulation (polyisocyanurate)
A 75mm PIR insulation board is one of the most popular choices on site. PIR offers a good balance of thermal performance, strength, and workability. A 75mm rigid insulation board made from PIR is easy to fix, trims cleanly, and is suitable for many wall, roof, and floor build-ups.
FAQ
Is 75mm insulation enough for walls?
In many situations, yes. A 75mm insulation thickness board provides solid thermal performance for both refurbishments and new builds. Whether it is enough depends on the wall type, existing construction, and the target U-value.
In older buildings, adding a 75mm thick insulation board often brings a dramatic improvement. In new builds, it may be used alongside other layers as part of a wider insulation system
How to fix 75mm insulation board?
- Walls: Mechanically fix the boards to masonry or timber, often with supplementary adhesive.
- Roofs: Fix boards between or below rafters using screws and washers.
- Floors: Boards are usually laid tightly together, either loose-laid (floating) or mechanically restrained, depending on the floor system.
How to cut 75mm insulation board?
Use:
- A fine-tooth hand saw, or insulation saw
- A straight edge to guide the cut
- A stable surface so the board does not bend
Score the facing material first, then cut through the insulation core in steady passes.
Where to buy a 75mm insulation board?
You can buy an insulation 75mm thickness board online from Insulation Wholesale. We stock EPS, phenolic, and PIR options in this thickness, ready to go from UK stock. Our team supports trade and commercial projects, so we offer trade discounts, pallet deals, and a fast quote process when you need numbers quickly. We focus on low wholesale pricing and fast nationwide delivery, including delivery to your site.
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75mm Celotex CW4075 Cavity Wall Insulation Board 1200mm x 450mm 4.32m2 Pack of 8 (4.32m2)
75mm Celotex CW4075 Cavity Wall Insulation Board is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring a low emissivity foil facing.
£66.13£79.36 Ex VATInc VAT£15.31£18.37 Per M2 Add to cart
