Roof Insulation

Roof insulation is one of the most impactful measures available in both new build and refurbishment projects, addressing a source of heat loss that accounts for up to 25% of a building's total thermal losses.

Available in rigid board, mineral wool and multifoil formats, roof insulation products cover a wide range of construction types and build-up configurations, from flat roof warm deck and inverted systems through to pitched rafter and ceiling applications. For projects where improving overall thermal efficiency is the priority, combining roof insulation with insulated loft boards can deliver a greater reduction in heat loss than either measure alone.

Polyisocyanurate (PIR) boards are the most widely specified material for roof applications in UK construction, valued for their high thermal performance relative to thickness, but the right product choice depends on roof type, target U-value, and the specific constraints of the build-up.

Types of Roof Insulation

Roof insulation divides into several distinct categories depending on roof construction and application, each with different material and thickness requirements.

Flat roof insulation boards are used in warm roof, cold roof and inverted roof build-ups, with rigid PIR boards the most widely specified option due to their high thermal performance in a compact thickness.

Pitched roof insulation covers rigid board solutions for use over or between rafters, most commonly specified where the roof space forms part of the habitable envelope.

Between rafter insulation is installed within the depth of the structural rafters in a pitched roof, typically combined with over or under rafter layers to achieve the required U-value.

Ceiling pads offer a practical solution for insulating directly above a ceiling plane in non-habitable roof spaces.

Multifoil insulation uses reflective foil layers to deliver thermal and vapour control in roof build-ups, and can be used alongside rigid boards to meet specification targets.

Roof Insulation Boards

Polyisocyanurate (PIR) is one of the highest-performing rigid insulation materials available for roof applications, with a typical thermal conductivity of 0.022 W/mK. That level of performance means target U-values can be achieved at a significantly thinner board depth compared with lower-performing materials, which is a meaningful advantage where structural depth or headroom is constrained.

Insulating a roof is one of the most cost-effective improvements available across most building types. The payback period on a well-specified roof insulation upgrade compares favourably with other fabric measures, and the combination of reduced heat loss and improved airtightness delivers a measurable improvement in both comfort and running costs.

Why Choose Insulation UK for Roof Insulation?

A Comprehensive Range of PIR, phenolic and mineral wool roof insulation boards in stock from 20mm to 200mm, covering flat roof, pitched roof, between rafter and ceiling applications.

Leading Manufacturers including Tekwarm, Celotex, Kingspan, Recticel and Rockwool. all available at competitive trade prices.

Fast UK-Wide Delivery with free delivery on orders over £500 ex VAT, and reliable nationwide logistics on every order.

Competitive Pricing across the full roof insulation range, backed by strong stock availability to keep your project on programme.

Expert Help and Advice from a team with over 50 years in the industry, available to support with specification, U-value targets and product selection across flat and pitched roof applications.