75mm Polystyrene Insulation

75mm polystyrene insulation boards are most commonly used for floor insulation, where the depth suits the thermal and compressive strength requirements of concrete slab construction without significantly impacting overall floor build-up height. Available in both expanded polystyrene (EPS) and extruded polystyrene (XPS), they are also used in wall and flat roof applications where a mid-range board thickness fits the required build-up.

Types of Polystyrene Insulation Available at 75mm

EPS boards at 75mm include standard white EPS across a full range of compressive strength grades, graphite-enhanced grey EPS for improved thermal performance, and compressible clay heave protection board for ground movement applications.

XPS boards at 75mm are available from Ravatherm in multiple grades.

Applications for 75mm Polystyrene Insulation

Floor insulation is the most common application for 75mm polystyrene boards. Laid beneath a concrete slab on a well-consolidated hardcore base, 75mm EPS or XPS delivers a continuous thermal break between the ground and the finished floor, with standard EPS delivering an R-value of between 1.97 and 2.21 m²K/W depending on grade and grey EPS or XPS achieving up to 2.5 m²K/W. In projects where a wet underfloor heating system is installed over the slab, the higher performance per millimetre of grey EPS or XPS helps limit the impact on overall floor build-up depth. The boards cut cleanly with a sharp hand saw and are lightweight enough to handle without mechanical assistance, making them practical for both self-build and contractor-led projects.

Wall insulation at 75mm suits cavity construction and internal dry-lining, and the same thickness is regularly specified for flat and inverted roof applications, particularly where XPS is laid above the waterproof membrane.

In new-build ground floor construction on clay subsoils, 75mm SPI Clayfill is frequently specified alongside standard floor insulation to absorb heave pressure before it reaches the slab.

Why Choose Insulation UK for 75mm Polystyrene Insulation?

A comprehensive range in stock across standard EPS, grey EPS, clay heave and XPS boards at 75mm, covering floor, wall, flat roof and foundation applications.

Products from trusted manufacturers including Jablite, Ravatherm and SPI, all available at competitive trade prices with no minimum order value.

Fast UK-wide delivery with free shipping on orders over £500 (ex VAT), and reliable nationwide logistics on every order despatched from our distribution centre in Rotherham.

Competitive pricing with some of the lowest 75mm polystyrene insulation prices available online, backed by strong stock availability and a trusted supply chain.

Expert help and advice from a team with over 50 years in the industry. Whether you are specifying a new-build ground floor slab, upgrading internal wall insulation on a period property, or sourcing clay heave boards for a development on shrinkable clay, we are here to make sure your project runs smoothly from start to finish.