This general-purpose thermal insulation board (polyisocyanurate) is engineered for high-performance insulation in floors, walls, and roofs. Featuring low thermal conductivity and foil facings on both sides, it minimizes heat loss while maintaining a thin profile, making it a standard choice for UK building regulations compliance.

Common applications include:

• Pitched & Flat Roofs: Installed between or over roof rafters, loft conversions, and warm flat roof constructions.

• Timber Frame & Cavity Walls: Fitted between timber studs or within masonry wall cavities to significantly reduce heat transmission.

• Solid Wall & Internal Lining: Fixed directly to internal brickwork or concrete walls before dry lining with plasterboard.

• Underfloor & Ground Floors: Laid beneath concrete floor slabs, screeds, or suspended timber floor joists to prevent ground cold bridge issues.

Available for collection from our Rugby branch or local delivery using our own fleet.

PIR will typically be delivered in one of our vans or pick-up trucks, unless ordered alongside larger goods. Delivery is kerbside and the final offloading position is always subject to safe access and the driver’s discretion.

Please tell us before delivery about:

• Narrow roads or restricted entrances
• Parked vehicles or limited turning space
• Overhead cables, trees or other obstructions
• Soft, sloping or unsuitable ground
• Any other access concerns

Enter your postcode on the product page to check your delivery area. We’ll confirm the delivery date after your order is placed.

How do I cut 2400 x 1200mm PIR insulation boards to size?

PIR insulation is easy to cut using standard hand tools. Measure your dimensions, mark with a straight edge, and cut using a fine-toothed handsaw or a dedicated insulation saw. For thinner boards (25mm–50mm), you can score deep into the foil facing with a heavy-duty utility knife and snap the board clean over a straight edge.

Why do PIR boards have foil facings on both sides?

The low-emissivity aluminium foil facings perform two vital functions: they act as a radiant heat barrier by reflecting thermal energy back into the room, and they serve as an effective vapour control layer (VCL) to prevent interstitial condensation when joints are taped.

Do I need to tape the joints between insulation boards?

Yes. Sealing all board joints, perimeter gaps, and service penetrations with aluminium foil tape creates a continuous vapour barrier. This prevents air leakage and stops warm, moist air from reaching cold structures where condensation could form.

What is the thermal conductivity (Lambda value) of PIR insulation?

Rigid PIR boards feature an exceptionally low thermal conductivity rating—typically 0.022 W/mK. This allows you to achieve current UK Building Regulations thermal performance targets with thinner insulation profiles than traditional mineral wool or EPS polystyrene.

Is PIR insulation board fire resistant?

PIR (polyisocyanurate) offers superior fire resistance compared to standard PUR (polyurethane) or EPS boards because it chars rather than melts when exposed to flame. However, it is generally classified under Euroclass E or F fire ratings, meaning it must be covered behind a protective fire-rated barrier (such as 12.5mm plasterboard) in inhabited domestic spaces.