Unilin Insulation Boards

What Is Unilin Insulation?

Unilin Insulation is the current brand name for the PIR insulation range formerly manufactured and sold as Xtratherm. The rebrand brought the product line under the wider Unilin group, but the boards themselves, their specifications and their manufacturing standards are unchanged. Searching for Xtratherm insulation, Xtratherm PIR or Unilin Xtratherm will lead to the same products listed on this page.

The Thin-R XT/PR-UF range stocked here consists of rigid polyisocyanurate (PIR) insulation boards with low-emissivity composite aluminium foil facings autohesively bonded to both sides of a closed-cell PIR core. The foil facings are thermal facings that contribute to insulation performance within cavity air spaces; they are not a vapour control layer, so a separate VCL should be specified where the build-up requires one.

Thicknesses and Range

The Unilin PIR insulation board range runs from 15mm through to 150mm in the following thicknesses: 15mm (full board and half board), 20mm, 25mm, 30mm, 40mm, 50mm, 60mm, 70mm, 75mm, 80mm, 90mm, 100mm, 110mm, 120mm, 125mm, 130mm, 140mm and 150mm. All full boards measure 2400 x 1200mm, covering 2.88m² per board. The 15mm half board measures 1200 x 1200mm, covering 1.44m².

Every thickness shares a declared thermal conductivity of 0.022 W/mK. Thermal resistance (R-value) scales with depth: a 50mm board delivers 2.25 m²K/W, a 100mm board delivers 4.50 m²K/W, and the thickest 150mm board reaches 6.80 m²K/W. Compressive strength across the range is 150 kPa at 10% compression (to BS EN 826), and vapour resistance exceeds 300 MNs/gm. The boards are square-edged, CFC and HCFC free with zero ozone depletion potential, and the closed-cell PIR core is rot-proof, moisture-resistant and dimensionally stable for the service life of the building.

Applications

Unilin Thin-R XT/PR-UF boards are general-purpose PIR insulation boards specified across a broad range of construction applications.

Floor Insulation

Unilin PIR boards are widely used in ground-supported floor constructions over concrete slabs with screed, suspended timber floors and floating floor systems. The 150 kPa compressive strength supports screed loads and underfloor heating without deformation. Thicknesses from 50mm to 150mm are commonly specified for floor applications, with the choice driven by the target U-value and available build-up depth. A damp-proof membrane is normally required beneath the insulation in ground floor constructions.

Roof Insulation

For pitched roofs, the boards are installed between and below rafters. For flat roofs, Unilin PIR is specified in warm-deck constructions and over-rafter systems. Thinner boards from 25mm to 75mm are used as supplementary layers or in depth-constrained refurbishment work, while thicknesses of 100mm and above are specified for primary insulation layers targeting demanding U-values. The 140mm and 150mm boards are specified where the design targets the lowest achievable roof U-values or where future-proofing against tightening energy standards is a design priority.

Wall Insulation

Unilin PIR insulation boards are used in timber framed walls, metal framed systems and as internal wall insulation in conjunction with plasterboard drylining. Board thickness depends on the framing depth and the target U-value, with 50mm to 100mm being the most commonly specified range for framed wall applications.

Performance and Certification

All Unilin Thin-R XT/PR-UF boards are BBA certified and manufactured to EN 13165 under quality systems certified to ISO 9001:2015 and ISO 14001:2015. Reaction to fire is classified Euroclass F to BS EN 13501-1. The range holds an Environmental Product Declaration (EPD) to EN 15804+A2 and ISO 14025, and a BES 6001 certificate for responsible sourcing. Always refer to the latest Unilin datasheet, Declaration of Performance and BBA certificate before specifying or ordering.

Why Choose Insulation UK for Unilin Insulation

• Full range in stock: every Unilin PIR board thickness from 15mm to 150mm is available to order, including the 15mm half board for smaller projects.
• Competitive trade pricing: volume and project-specific pricing is available; contact our team at 03003 034 578 or sales@insulationuk.co.uk for a quote.
• Free delivery on orders over £500 ex VAT: helping to keep project costs down on larger insulation orders.
• Technical knowledge: our team can advise on the right Unilin board thickness and specification for your project, from a single-room refurbishment to a full new build.
• Fast UK delivery: reliable nationwide dispatch to keep your project on schedule.