PIR Insulation

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.

What is PIR insulation board?

PIR foam is made through a chemical reaction that results in a closed-cell structure that traps gas. Because blowing agent gas has lower thermal conductivity than air, it is among the most energy-efficient insulating materials on the market.

The material’s low thermal conductivity, combined with its ease of handling and versatility in a variety of applications, has made it increasingly popular among architects and contractors.

The boards do not work on their own, though. Each piece of PIR is wrapped in a facing – usually a foil, a glass-tissue layer, or a bitumen-ready coating – and those facers do as much work as the foam itself. They control moisture, help the board bond to membranes, stiffen the panel, and can influence aspects of fire performance.

What are PIR insulation panels used for?

PIR insulation is suited to diverse applications:

  • Flat roofs. Bitumen-ready boards complement torch-on felt systems; glass-tissue boards are used under mechanically fixed single-ply or metal membranes.
  • Pitched roofs (between, under, or over rafters). Between rafters, it keeps the structure warm. Under rafters, it doubles as a vapour-control layer when foil-faced. Over rafters, it creates a continuous warm-roof layer with minimal thermal bridging.
  • Cavity walls. They are cut to fit neatly between wall ties and typically use reflective foil facers to boost performance in partial-fill systems.
  • Ground floors and suspended timber floors. Used with concrete slabs, screeds, and timber joists.
  • External wall systems, linings & special details. Often used in dry-lining boards (PIR bonded to plasterboard), insulated render systems, or warm balcony and threshold build-ups.

Types of PIR insulation panels

PIR insulation panels can be grouped by application:

PIR for flat roofs

These are used on concrete, timber, or metal decks for warm roofs. Flat-roof PIR always needs facings that work with a membrane, so the facer type is a big deal here.

Common facings in Flat-Roof PIR

a) Bitumen-coated glass-tissue facer

  • Made for torch-on felt and multi-layer bituminous membranes.
  • Usually topped with a polypropylene fleece to prevent slippage.
  • Found on products like Kingspan TR24.

b) Glass-tissue (mineral-coated) facer 

  • Slightly tougher, used when the roofer wants improved stability under hot works.
  • Compatible with adhesives and some mechanically fixed systems.
  • An example is Kingspan TR27.

c) Foil facer (less common for roofs) 

  • Used mainly for fully adhered and single-ply roof finishes, or when designers want a reflective layer.
  • Common on universal PIR boards, but not suitable for torch-on systems.
  • Example Kingspan TR26 ( used only where permitted by the roofing system manufacturer).

PIR for pitched roofs (between, under, or over rafters)

These are used in loft conversions, attic refurbishments, warm pitched roofs, and dormer cheeks. They are moisture-tolerant, rigid, and easy to cut around rafters.

Common facings in Pitched-Roof PIR

Foil-faced PIR (the standard) 

  • Aluminium foil on both sides.
  • Acts as a built-in vapour control layer, convenient under rafters.
  • Provides excellent thermal performance and a clean surface for taping joints.

Examples of pitched-roof PIR Boards

PIR for cavity walls (masonry construction)

For new-build cavity walls, partial-fill, or full-fill, depending on design. They resist moisture ingress, fit neatly between wall ties, and prevent thermal bridging.

Common facings in cavity PIR

a) Foil facers (highly reflective) 

  • Most cavity-wall PIR systems have low-emissivity foil on both sides.
  • Helps boost performance in the cavity airgap.
  • Also provides moisture resistance.

b) Textured/embossed foil 

  • Some manufacturers use micro-patterned foil to improve adhesion or prevent sticking during installation.

c) Water-repellent coated facers 

  • Applied to full-fill boards to provide extra rain resistance during construction.

Examples of cavity-wall PIR boards

PIR for floors (screeded or timber suspended)

For ground floors, suspended timber floors, and refurb work where weight and compressive strength matter. Floor PIR has high compressive strength, resists moisture, and keeps thermal performance stable beneath screed.

Common floor-PIR Facings

a) Foil facers (most common)

  • Acts as a vapour barrier under screed but does not replace a DPM where required.
  • Helps with taped joints and radon barrier compatibility.

b) Glass-tissue facers

  • Used on boards designed for adhesive bed fixing or where foil interaction is not needed.

Examples of floor PIR boards

Benefits of PIR board insulation

  • PIR is lighter than mineral wool insulation for similar thermal performance.
  • Easy to install – simple handling, straightforward application.
  • Reduces heat loss.
  • PIR insulation is thin, which means less material results in lighter structures and saves on building materials.
  • The foil facings have a high water vapour resistance and will therefore provide significant resistance to water vapour transmission.
  • Resistant to the damage caused by water vapour and mould.
  • Excellent coverage – 2400 x 1200mm panel provides a coverage area of 2.88m².
  • Manufactured using blowing agents with zero ODP and low GWP.

Why choose our PIR boards?

We stock a full range of PIR boards from all the major brands – from everyday 25–150mm sheets right up to heavy-duty roof and floor specs, depending on the product.

We offer competitive PIR insulation prices for single boards, as well as wholesale, bulk, and trade discounts when you are loading up for a full job.

We provide fast dispatch, nationwide delivery, and dependable timescales.

At Insulation Wholesale, you can purchase PIR Insulation at low wholesale prices with fast delivery for most of items within 2-5 days. Competitive rates guaranteed.

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