20mm Unilin Thin-R PIR Insulation Board

Unilin Insulation (formerly Xtratherm) now provides superior thermal performance.

20mm Unilin Thin-R PIR Insulation Board (2400mm x 1200mm x 20mm) delivers ultra-thin, rigid foil-faced polyisocyanurate (PIR) thermal foam insulation with exceptional thermal conductivity of just 0.022 W/mK. Engineered for pitched roofs, walls, floors, and timber or steel-framed construction systems.

About

20mm Unilin PIR insulation excels in pitched roof applications—whether ventilated, hybrid, or warm roof designs—providing outstanding U-values whilst preserving internal space. Roof construction represents a critical thermal boundary where heat loss is most significant. This board minimises heat escape and delivers excellent thermal bridging performance. Suitable across multiple construction scenarios including pitched roof systems, wall cavities, and floor structures, the product combines thinness with lightweight handling and straightforward installation. The board resists fire, repels water, and carries minimal environmental impact.

Product Details

Thickness: 20mm

Length: 2400mm

Width: 1200mm

Available Thicknesses: 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 60mm, 65mm, 70mm, 75mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm, 165mm

Maximum Board Weight: 0.45 kg/m²

Thermal Resistance: 0.91 m²K/W

Thermal Conductivity: 0.022 W/mK

Compressive Strength: >150 kPa

Water Vapour Resistivity: >100 MNs/gm

Density (Foam Core): 30–32 kg/m³

Surface Spread of Flame: Class 1

Reaction to Fire: E

Finish: Aluminium Foil Facings

Applications: Roofs, Walls, Floors, Timber & Steel Frame

ETA Notification: Yes

Features: Versatile | High-performance | Rigid

Warm roof construction represents an excellent solution for insulating complex roof designs. Installing insulation above—or above and between—roof timbers maintains the structural envelope at internal conditions, reducing thermal stress and condensation risk.

The 20mm PIR insulation requires storage on a clean, level surface away from ground contact and must remain covered. Polythene wrapping alone does not provide sufficient outdoor protection. During storage and construction, take care to shield the insulation from damage. The insulation boards cut easily with a sharp knife or fine-toothed saw.

Key Facts

1. Unilin 20mm PIR achieves an A+ rating under the BRE Green Guide.
2. Certified Lambda value of 0.022 W/mK.
3. Minimises intrusion into living space.
4. Reduces condensation risk.
5. Low-emissivity foil facings.
6. Lightweight and simple to fit.
7. Enhanced thermal bridging control.
8. Ventilated roof compatible.
9. Warm roof compatible.
10. Hybrid roof compatible.

Browse our Unilin range and filter by thickness or coverage using the left-hand menu. For project suitability advice or bulk quotations, contact us on +4402038839057, email sales@insulationbee, or use Live Chat for the best UK insulation prices.