Where to buy PIR insulation?

You can buy PIR board insulation online from specialist insulation stores such as Insulation Wholesale. As a leading PIR insulation supplier, we stock a full range of panels for walls, floors, roofs, and lofts – from foil-faced wall panels to roof-ready boards and heavy-duty floor insulation. If you are budgeting for a project, our team can provide quick, accurate quotes so you know the current PIR insulation prices before you order.

How to cut PIR insulation?

Mark your cut line. Use a straightedge or long level. If your line is crooked, your cut will be too. Score the foil first. Take a sharp utility knife and lightly score along your line. This does not slice the board – it just breaks the foil, leaving a neat edge. Deepen the cut. Run your knife over the same line three or four times. You will feel it sink deeper each pass. For thinner boards (25–50mm), you can usually cut through the material with the knife alone. Snap the board. For thicker boards (75–150mm), once the knife has cut through the foil and a bit into the foam, tilt the board over an edge or your knee and snap it along the scored part. The core breaks cleanly. Trim the back. After snapping, the face will be clean-cut, and the back partially torn. Score the back foil with your knife and slice off the remaining foam. Optional: use a handsaw. If you prefer one tool start to finish, a fine-tooth handsaw works well. It is slightly messier but great for deep cuts or angled pieces.

How to install PIR insulation?

1.Between Studs, Joists, or Rafters This is the classic “cut to fit and friction-fix” method. Cut each board 3–5 mm wider than the gap. Fit it into the space so it grips the sides. That slight pressure keeps it snug. Make sure the face of the board sits flush with the timber so your plasterboard or internal lining lands cleanly. Tape the foil joints to get a tighter vapour barrier. PIR is rigid enough to bridge the gap, and the foil face helps stop air movement. Always follow system-specific guidance for vapour control and ventilation requirements. 2.Over Joists, Rafters, or Stud Walls (Continuous Layer) This provides the best thermal performance by eliminating cold spots. Fix the boards directly over the timber using insulation fixings or long screws with washers. Stagger the joints so no straight lines run through the insulation. Tape all joints with foil tape to seal the layer. Fit your plasterboard or deck on top using long screws that reach the timber below. The full sheet covers every timber, giving a more even thermal layer. 3.Solid Masonry Walls (Internal Facing) This is the "insulated lining board" approach. Dot-and-dab adhesive or mechanical fixings can be used, depending on the spec. Boards must sit flat with no steps between them. Tape joints, then add plasterboard over the top, or use insulated plasterboard that includes PIR. It creates a warm internal surface and stops heat from bleeding into the cold wall. 4.Floors Most PIR in floors is installed under the screed or under a chipboard deck. Lay a DPM if needed. Put PIR boards tightly together with staggered joints. Tape where required, then add your screed or deck on top. The rigid foam handles the load once it is supported by the layers above. 5.Flat Roofs Both warm-roof and inverted-roof setups commonly use PIR. Lay the boards over the roof deck. Stagger joints. Mechanically fix or bond, depending on the roof system. Add the waterproofing membrane over the top.

Can PIR insulation get wet?

PIR itself does not soak up water easily. So if the board gets a light splash or short-term exposure, it will not suddenly fall apart or lose its thermal performance. But it is not designed to stay wet because this can affect long-term stability. Long-term immersion or condensation behind the board can degrade facers or structure.

Can you use PIR insulation in loft?

Yes, PIR insulation works very well in a loft. Between Rafters Fit PIR panels snugly between the rafters, leaving the required ventilation gap above – usually 25–50mm, depending on the roof. Seal small gaps with foam or tape to prevent cold bridges. Under Rafters (to boost U-value) A continuous layer of foil-faced PIR is fixed across the underside of the rafters. This adds thermal performance, covers up imperfect cuts between rafters, and the foil layer acts as a vapour-control layer once joints are taped. Over Rafters (warm roof method) If you are re-roofing, PIR slabs can be laid on top of the rafters before the breather membrane and tiles go on. This gives you a full warm roof with minimal thermal bridging – the most efficient loft system, but only practical during roof replacement.

PIR Polyisocyanurate Insulation At Low Wholesale Prices

PIR Polyisocyanurate Insulation Thermal

The polyisocyanurate (PIR) Insulation board is one of the most popular construction materials, primarily used for pitched roofs, walls, and floors in domestic and industrial projects.

We stock the most desirable brands, including Ecotherm, Recticel, and Kingspan PIR insulation. These boards are available in various thicknesses from 20mm to 150mm. They deliver an excellent thermal conductivity of 0.022 W/mK across all thicknesses and boast superb compressive strength.

Read more about Polyisocyanurate PIR Insulation.

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Products in PIR Polyisocyanurate Insulation

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110mm Celotex XR4110 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2

110mm Celotex XR4110 is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Celotex is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.

£47.81£57.37 Ex VATInc VAT
£16.60£19.92 Per M2
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130mm Celotex XR4130 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2

130mm Celotex XR4130 is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Celotex is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.

£61.94£74.33 Ex VATInc VAT
£21.51£25.81 Per M2
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130mm Recticel Eurothane GP PIR Insulation Board 2400mm x 1200mm (8′ x 4′) 2.88m2

130mm Recticel Eurothane GP is a polyisocyanurate (PIR) insulation core with composite aluminium foil facings on both sides. Recticel is a multi-purpose insulation board suitable for use in pitched roofs, ceilings, floors and walls.

£54.66£65.59 Ex VATInc VAT
£18.98£22.78 Per M2
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20mm Kingspan Therma TP10 / TF70 / TW55 PIR Insulation Board 2400mm x 1200mm (8′ x 4′) Pack of 15 (43.20m2)
All three models 20mm Kingspan Therma PIR Insulation Board:
- 20mm Thermapitch TP10
- 20mm Thermafloor TF70
- 20mm Thermawall TW55
share the same high-performance PIR core and low-emissivity foil facings, offering excellent thermal efficiency and easy installation. Although labeled differently, these boards share identical technical specifications.

No longer in production.
£319.28£383.14 Ex VATInc VAT
£7.39£8.87 Per M2
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60mm Celotex CW4060 Cavity Wall Insulation Board 1200mm x 450mm 5.4m2 Pack of 10

60mm Celotex CW4060 Cavity Wall Insulation Board is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring a low emissivity foil facing.

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90mm Ecotherm Eco-Cavity Full Fill Insulation Board Tongue And Groove 1200mm x 450mm Pack of 4 (2.16m2)

Eco-Cavity Full Fill is suitable for full fill cavity wall applications while maintaining a residual 10 mm cavity. The residual cavity helps resist moisture transfer, aids installation, and accommodates mortar squeeze. The tongue and groove edges to ensure a continuous layer of insulation, increasing protection from wind driven rain and aiding installation.

£58.00£69.60 Ex VATInc VAT
£26.85£32.22 Per M2
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