PIR Insulation Boards

PIR insulation boards from Kingspan, Recticel and Mannok in 20mm to 160mm, sold per sheet or pack at trade prices and delivered to England and Wales in 2–3 working days.

Which PIR board do I need?

PIR (polyisocyanurate) boards give high thermal performance for their thickness – most general-purpose foil-faced boards have a thermal conductivity of 0.022 W/mK. We stock:

  • General purpose 2400 × 1200mm boards for floors, walls and pitched roofs: Kingspan Thermapitch TP10 (25–150mm), Recticel Eurothane GP (25–150mm) and Mannok Therm.
  • Cavity wall boards: Kingspan Thermawall TW50 and Recticel Eurowall partial-fill (1200 × 450mm), Recticel Eurowall+ and Mannok IsoCavity full-fill.
  • Flat roof boards: Kingspan Thermaroof TR24, TR26 and TR27 and Recticel Eurodeck and Powerdeck, for mechanically fixed, adhered or torch-on waterproofing.

Thickness depends on the U-value you need to hit and the construction – try our free PIR U-value calculator or read what thickness of PIR insulation do I need?. For dry-lining walls, look at insulated plasterboard instead. Check the product datasheet (linked on each product page) and Building Regulations before ordering.

Delivery: prices are ex VAT. We deliver to England and Wales in 2–3 working days – free on orders over £500 ex VAT, £50 below that, with a £400 minimum order.

Looking for Celotex or EcoTherm? Celotex GA4000 and EcoTherm Eco-Versal are general-purpose foil-faced PIR boards rated 0.022 W/mK. Kingspan Thermapitch TP10, Recticel Eurothane GP and Mannok Therm boards in this range have the same 0.022 W/mK rating, so a board of the same thickness gives the same U-value. Looking for cheap PIR insulation? Every board is priced at trade price ex VAT, per sheet or per pack, so you can compare 25mm, 50mm, 100mm and 150mm boards like for like.

What thickness of PIR do I need? Check your floor, wall or roof against Building Regulations (Part L) targets with our free U-value calculator. Open U-value calculator

105 products

PIR insulation boards: buying guide

PIR (polyisocyanurate) is a rigid foam board with foil or glass-tissue facings. Because it insulates well for its thickness, it’s the usual choice where space is tight: between and over rafters, under floor screeds, in partial-fill cavities and on flat roofs.

Choose the right type of board

  • General purpose boards (2400 × 1200mm) – Recticel Eurothane GP, Kingspan Thermapitch TP10 and Mannok Therm, for pitched roofs, floors and walls. The foil-faced boards we sell list a thermal conductivity (λ) of 0.022 W/mK on their product pages.
  • Cavity wall boards (1200 × 450mm) – partial-fill boards such as Kingspan Thermawall TW50 and Recticel Eurowall leave a clear cavity; full-fill boards such as Recticel Eurowall+ and Mannok IsoCavity have tongue and groove edges and fill the cavity.
  • Flat roof boards – Kingspan Thermaroof and Recticel Powerdeck and Eurodeck boards are made for warm-deck roofs. The facing has to suit the waterproofing (mechanically fixed, adhered or torch-on), so check the board’s datasheet against your membrane.
  • Phenolic boards – Kingspan Kooltherm boards list a lower λ (0.019 W/mK for most of the range), so you can hit the same U-value with a thinner board.

Kooltherm or PIR? Phenolic boards are thinner for the same R-value but cost more. Our Kooltherm K103 vs PIR comparison shows how much thicker PIR needs to be, and what it saves per m², with a free printable one-page PDF.

R-values by thickness

The R-value (thermal resistance) of a board goes up with thickness and down with λ. For the λ values listed on our product pages. PIR (λ 0.022 W/mK): Eurothane GP, Thermapitch TP10, Thermawall TW50, Eurowall; Phenolic (λ 0.019 W/mK): Kooltherm K103, K107, K108, K112.

ThicknessPIR
λ 0.022		Phenolic
λ 0.019
25mm1.101.30
50mm2.252.60
75mm3.403.90
100mm4.505.25
120mm5.456.30
150mm6.807.85

R-values in m²K/W, worked out as thickness (m) ÷ λ and rounded down to the nearest 0.05. Each product page has a table for the exact thicknesses in that range. Check the manufacturer’s declaration of performance and your U-value calculation for Building Regulations. Flat roof boards such as Thermaroof TR27 and Powerdeck list λ 0.024–0.027 depending on thickness, so see their product pages.

How thick should it be?

The thickness you need depends on the U-value required for the element (floor, wall or roof) and on everything else in the build-up. Use our PIR U-value calculator to find a thickness, read what thickness of PIR insulation do I need?, then use the insulation calculator to work out how many boards or packs to order. Always confirm the final specification with your building control body or designer.

Fitting tips

  • Cut boards tightly and tape joints with foil tape to keep them airtight.
  • Check each board’s datasheet (linked on the product page) for the correct fixings, vapour control and fire requirements.
  • Store boards flat, off the ground and under cover.

Delivery and minimum order: prices are shown ex VAT. We deliver to England and Wales, usually in 2–3 working days. There’s a £400 ex VAT minimum order, delivery is £50 ex VAT on orders under £500 ex VAT and free over £500 ex VAT. Need a price for a large or mixed load? Call 03330 908479.

Frequently asked questions

What’s the difference between PIR and phenolic insulation?

Both are rigid insulation boards. Phenolic boards such as Kingspan Kooltherm list a lower thermal conductivity (0.019 W/mK for most of the range) than foil-faced PIR (0.022 W/mK), so they can be thinner for the same U-value, but they usually cost more per square metre.

How many PIR boards do I need?

A 2400 × 1200mm board covers 2.88m². Divide your area by 2.88, add around 10% for cutting and round up. Our insulation calculator does this for you, including packs of cavity and flat roof boards.

Can I use general purpose PIR in a cavity wall?

Cavity walls normally use boards made for the job, such as Kingspan Thermawall TW50 or Recticel Eurowall, which are sized to suit wall tie spacing. Check the manufacturer’s literature before using any board in a cavity.

What thickness of PIR do I need for Building Regulations?

It depends on the element and the rest of the construction. Try our PIR U-value calculator and confirm the result with building control.

Do I need to tape the joints?

Taping the joints with foil tape helps keep the insulation airtight and is often part of the manufacturer’s installation guidance, especially where the board forms the vapour control layer.

Is there a minimum order and how much is delivery?

There’s a £400 ex VAT minimum order on insulation and building materials. Delivery to England and Wales is £50 ex VAT on orders under £500 ex VAT and free over £500 ex VAT, usually in 2–3 working days.

PIR (polyisocyanurate) insulation boards are a top choice for thermal insulation in the construction industry thanks to their closed-cell structure, low thermal conductivity, and exceptional thermal performance. Whether you’re working on residential homes, commercial projects, or industrial builds, PIR boards deliver reliable insulation that stands out in terms of both efficiency and cost-effectiveness.

  • Superior Energy Efficiency
    PIR insulation boards excel in reducing heat loss, helping to maintain a comfortable indoor temperature year-round. With a thermal conductivity as low as 0.022 W/mK, these boards provide excellent U-values, meaning less energy is required to heat or cool a building. This makes them a smart choice for anyone looking to lower energy costs while boosting energy efficiency.
  • Lightweight and Easy to Install
    Contractors and DIYers alike prefer PIR insulation for being lightweight and simple to handle. Whether you’re cutting boards to fit cavity wall studs, timber joists, or a concrete slab, installation is quick and easy.
  • Durable with Long-Term Benefits
    PIR insulation is made with a rigid thermal insulation core that withstands wear and tear while delivering consistent performance over time. Its two aluminium foil facings or mineral glass coatings help reinforce its durability and enhance thermal efficiency.
  • Eco-Friendly Features
    These insulation boards come with zero ozone depletion potential and low-emissivity foil facings, ensuring they align with sustainability goals in building construction.

PIR insulation is one of the most versatile solutions available for modern construction projects, thanks to its adaptable nature and high thermal performance. Common applications include:

  • Internal Wall Insulation
    Installed on solid masonry walls or timber frame studs, PIR insulation reduces heat transfer and creates a reliable thermal barrier. This makes it especially effective for solid masonry internal linings.
  • Cavity Wall Insulation
    PIR cavity wall boards act as a partial fill cavity insulation, efficiently trapping air within its closed-cell structure to enhance energy efficiency.
  • Roof Insulation
    Ideal for both pitched and flat roofs, PIR boards are compatible with timber frame constructions and can be installed beneath OSB boards or applied directly for airtight insulation.
  • Floor Insulation
    From concrete slabs to spaces between timber joists, PIR insulation boards are a go-to for floor applications, thanks to their high compressive strength and lightweight structure.

We stock a range of PIR insulation products to suit your specific project needs. Here are the top options to consider:

  • General Purpose PIR Boards
    Perfect for multi-application use, from walls to floors and roofs.
  • Celotex PIR Insulation Boards
    Designed for exceptional thermal performance and trusted for various building applications.
  • Kingspan PIR Insulation
    Offering high-quality insulation with low thermal conductivity and premium fire resistance.
  • Cavity Wall PIR Boards
    Specifically developed for cavity walls to minimise heat transfer and energy loss.

When purchasing PIR insulation, keep the following factors in mind to make the right choice:

  1. Application Requirements
    Determine whether you need PIR boards for flat roofs, cavity walls, or internal wall insulation. Each application may require a specific thickness or feature, such as two aluminium foil facings or a closed-cell structure.
  2. Thermal Ratings
    Check the material’s thermal conductivity (W/mK) value to ensure it aligns with your project objectives, such as achieving the best U-value.
  3. Brand Quality
    Select products from trusted manufacturers like Celotex or Kingspan for reliability and performance.
  4. Thickness Options
    PIR boards come in thicknesses ranging from 25mm to 150mm, making it easy to customise according to project demands. Remember, PIR boards deliver high thermal efficiency at only half the thickness of some alternative solutions.
  5. Delivery and Support
    Ensure your supplier offers fast delivery and expert advice to guide your purchase.