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PIR Insulation Board

PIR insulation, also called Polyisocyanurate or PIR board, is a high-performance, rigid foam insulation with excellent thermal conductivity. It is moisture resistant and offers strong fire resistance. Suitable for lofts, floors, and walls, PIR board is space-saving thanks to its thin design. Our range of PIR insulation includes various sizes from Unilin.

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    Unilin CavityTherm Full Fill Insulation PIR Board 1200 x 450 x 100mm

    CavityTherm is an innovative built-in insulation for traditional walls that achieves passive level U-Values as low as 0.12 W/m2K with excellent thermal bridging detailing in cavities less than 150mm wide. The board includes specifically designed rebated...
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    Unilin CavityTherm Full Fill Insulation PIR Board 1200 x 450 x 125mm

    CavityTherm is an innovative built-in insulation for traditional walls that achieves passive level U-Values as low as 0.12 W/m2K with excellent thermal bridging detailing in cavities less than 150mm wide. The board includes specifically designed rebated...
  • CavityTherm%20Board.jpg.jpeg

    Unilin CavityTherm Full Fill Insulation PIR Board 1200 x 450 x 150mm

    CavityTherm is an innovative built-in insulation for traditional walls that achieves passive level U-Values as low as 0.12 W/m2K with excellent thermal bridging detailing in cavities less than 150mm wide. The board includes specifically designed rebated...
  • CavityTherm%20Board.jpg.jpeg

    Unilin CavityTherm Full Fill Insulation PIR Board 1200 x 450 x 90mm

    CavityTherm is an innovative built-in insulation for traditional walls that achieves passive level U-Values as low as 0.12 W/m2K with excellent thermal bridging detailing in cavities less than 150mm wide. The board includes specifically designed rebated...
  • ECOCT%20EXT%20CRN.jpg.jpeg

    Unilin CavityTherm Full Fill Int Corner Insulation PIR Board 1200 x 450 x 100mm

    CavityTherm Corner Fill is a preformed panel of CavityTherm that folds to provide a 90° corner either external or internal. Corner boards ensure excellent detailing and provide a template for setting out of outer brickwork.
  • ECOCT%20EXT%20CRN.jpg.jpeg

    Unilin CavityTherm Full Fill Int Corner Insulation PIR Board 1200 x 450 x 125mm

    CavityTherm Corner Fill is a preformed panel of CavityTherm that folds to provide a 90° corner either external or internal. Corner boards ensure excellent detailing and provide a template for setting out of outer brickwork.
  • ECOCT%20EXT%20CRN.jpg.jpeg

    Unilin CavityTherm Full Fill Int Corner Insulation PIR Board 1200 x 450 x 150mm

    CavityTherm Corner Fill is a preformed panel of CavityTherm that folds to provide a 90° corner either external or internal. Corner boards ensure excellent detailing and provide a template for setting out of outer brickwork.
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    Unilin CavityTherm Full Fill Riser Insulation PIR Panel 1200 x 225 x 100mm

    The CavityTherm half board allows you to position your insulation at floor levels and positions it directly under the Decks Post-Insulation-Riser (DIP). The CavityTherm can be used on individual floors as well as shared walls, thereby increasing thermal...
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    Unilin CavityTherm Full Fill Riser Insulation PIR Panel 1200 x 225 x 125mm

    The CavityTherm half board allows you to position your insulation at floor levels and positions it directly under the Decks Post-Insulation-Riser (DIP). The CavityTherm can be used on individual floors as well as shared walls, thereby increasing thermal...
  • CT_PIR%20RISER.jpg.jpeg

    Unilin CavityTherm Full Fill Riser Insulation PIR Panel 1200 x 225 x 150mm

    The CavityTherm half board allows you to position your insulation at floor levels and positions it directly under the Decks Post-Insulation-Riser (DIP). The CavityTherm can be used on individual floors as well as shared walls, thereby increasing thermal...
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    Unilin CavityTherm Full Fill Top Insulation PIR Panel 1200 x 225 x 100mm

    A CavityTherm half-board that is used to finish wall insulation heights when a full board is not required. Uses less materials and generates less waste than traditional methods.
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    Unilin CavityTherm Full Fill Top Insulation PIR Panel 1200 x 225 x 125mm

    A CavityTherm half-board that is used to finish wall insulation heights when a full board is not required. Uses less materials and generates less waste than traditional methods.
  • CT_PIR%20TOP%20PANEL.jpg.jpeg

    Unilin CavityTherm Full Fill Top Insulation PIR Panel 1200 x 225 x 150mm

    A CavityTherm half-board that is used to finish wall insulation heights when a full board is not required. Uses less materials and generates less waste than traditional methods.
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    Unilin CavityTherm100 Hockey Service V Insulation PIR Board 1200 x 75 x 100mm

    Hockey Service voids allows for easy access to the cable that supplies the meter box and is preformed to fit the insulation. It has a frost line of 28mm, with an R value of 6.9m2k/w
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    Unilin CavityTherm100 Meter Box Insulation PIR Panel 1200 x 600 x 100mm

    The preformed meter box accessory allows a recess space for placement of meter box, leaving the insulation to run in a continuous plane. The CavityTherm150 Meter Box Preform is based on the CavityTherm140 but with a tighter specification for more precise...
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    Unilin CavityTherm125 Hockey Service V Insulation PIR Board 1200 x 75 x 125mm

    Hockey Service voids allows for easy access to the cable that supplies the meter box and is preformed to fit the insulation. It has a frost line of 28mm, with an R value of 6.9m2k/w
  • CT_PIR%20METRE%20BOX.png

    Unilin CavityTherm125 Meter Box Insulation PIR Panel 1200 x 600 x 125mm

    The preformed meter box accessory allows a recess space for placement of meter box, leaving the insulation to run in a continuous plane. The CavityTherm150 Meter Box Preform is based on the CavityTherm140 but with a tighter specification for more precise...
  • CT_PIR%20HOCKEY.jpg.jpeg

    Unilin CavityTherm150 Hockey Service V Insulation PIR Board 1200 x 75 x 150mm

    Hockey Service voids allows for easy access to the cable that supplies the meter box and is preformed to fit the insulation. It has a frost line of 28mm, with an R value of 6.9m2k/w
  • CT_PIR%20METRE%20BOX.png

    Unilin CavityTherm150 Meter Box Insulation PIR Panel 1200 x 600 x 150mm

    The preformed meter box accessory allows a recess space for placement of meter box, leaving the insulation to run in a continuous plane. The CavityTherm150 Meter Box Preform is based on the CavityTherm140 but with a tighter specification for more precise...
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    Unilin ECO Cavity Wall Rebate Edge Insulation PIR Board 1200 x 450 x 100mm

    Cavity Wall 360 is a bio-enhanced partial fill wall insulation system. The system incorporates robust facings, engineered jointing details, pre-formed corners and has a certified Lambda of 0.020 W/mK.
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    Unilin ECO Cavity Wall Rebate Edge Insulation PIR Board 1200 x 450 x 110mm

    Cavity Wall 360 is a bio-enhanced partial fill wall insulation system. The system incorporates robust facings, engineered jointing details, pre-formed corners and has a certified Lambda of 0.020 W/mK.
  • ECOCT%20EXT%20CRN.jpg.jpeg

    Unilin ECO CavityTherm External Corner Insulation PIR Board 1200 x 450 x 110mm

    An engineered system providing added resilience against increases in wind-driven rain resulting from climate change. CavityTherm 360 is a bio-enhanced high performance composite board of enhanced PIR with a Lambda value as low as 0.020 W/mK for full fill...
  • ECOCT%20EXT%20CRN.jpg.jpeg

    Unilin ECO CavityTherm External Corner Insulation PIR Board 1200 x 450 x 125mm

    An engineered system providing added resilience against increases in wind-driven rain resulting from climate change. CavityTherm 360 is a bio-enhanced high performance composite board of enhanced PIR with a Lambda value as low as 0.020 W/mK for full fill...
  • ECOCT%20EXT%20CRN.jpg.jpeg

    Unilin ECO CavityTherm External Corner Insulation PIR Board 1200 x 450 x 150mm

    An engineered system providing added resilience against increases in wind-driven rain resulting from climate change. CavityTherm 360 is a bio-enhanced high performance composite board of enhanced PIR with a Lambda value as low as 0.020 W/mK for full fill...

PIR Insulation Board

What are PIR boards?

PIR stands for Polyisocyanurate — a rigid type of thermal insulation made from plastic foam.

First introduced in the 1960s as an upgrade to PUR (Polyurethane) boards, PIR offers better insulation performance and versatility.

Where can PIR Insulation be used?

  • Walls – Products like Ecoliner are ideal for insulating and drylining internal walls. Eco-Versal suits timber frame walls, with both sides faced in aluminium foil for improved efficiency. As the name suggests, Eco Cavity is designed for cavity or masonry walls and fits standard brick and block dimensions.
  • Flooring – Works with most flooring types, including timber, solid concrete, and suspended floors. Insulating floors helps prevent heat loss and keeps interiors warmer.
  • Lofts – Loft spaces are one of the most common areas for heat loss. Using PIR or PUR insulation can improve energy efficiency and reduce heating costs.
  • Eco-Versal versatility – A popular PIR option that works across pitched roofs, walls, loft ceilings, and floors for consistent thermal performance throughout the home.

Frequently Asked Questions

What is pir insulation?
Polyisocyanurate (PIR) is one of the most efficient insulation materials used in construction. Pir insulation boards are typically available in the following sizes: 25mm, 75mm, 100mm, 120mm and 150mm.
What does pir stand for in pir insulation?
Polyisocyanurate, also referred to as PIR, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation.
Is pir insulation flammable?
Whilst we urge you to refer to the manufacturer’s fire testing certifications, commercially available PIR insulation is not typically flammable.
Is pir insulation waterproof?
While PIR insulation boards are generally resistant to moisture, they are not fully waterproof.
What is the difference between pir and phenolic insulation?
As with the PIR/PUR boards above, phenolic insulation boards also have a closed cell structure. Phenolic board has a slightly higher r-value (higher is better, unlike u-values) and a slightly thinner profile than PIR/PUR boards due to the manufacturing process.

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