A Guide to PIR Insulation Boards


In the world of energy efficiency and home insulation, PIR (Polyisocyanurate) insulation boards have become a popular choice due to their impressive thermal properties, and versatility and offer an excellent balance between cost, performance and durability.
What is a PIR Insulation Board?
PIR insulation boards, short for Polyisocyanurate boards, are a type of rigid foam board commonly used to insulate walls, roofs, and floors. They offer high thermal performance, helping to retain heat in buildings, which in turn reduces energy consumption and lowers utility bills.
What are PIR boards made of?
PIR boards are constructed by combining polyol and MDI (methylene diphenyl diisocyanate) under high pressure to form a rigid foam. This foam is then sandwiched between two layers of facing materials, typically aluminium foil or glass tissue. These facings help improve the board's insulation performance and provide durability.
The rigid foam structure is what gives PIR boards their excellent insulating properties, and the added facings make them moisture-resistant, lightweight and easy to handle.
What can you use a PIR Insulation Board for?
PIR insulation boards are incredibly versatile and can be used in a wide range of applications such as:
- Walls – PIR boards can be used in both internal and external walls to improve thermal and sound insulation.
- Roofs – PIR boards are popular for pitched, flat, and inverted roofs due to their lightweight structure and excellent insulating properties.
- Floors – PIR boards are used to insulate solid and suspended floors, helping reduce heat loss from buildings.
- Cavities – PIR boards can be used for cavity wall insulation, where they are placed between two walls to trap heat inside.
In both residential and commercial properties, PIR insulation is widely used to meet building regulations and enhance energy efficiency.
What sizes do PIR insulation boards come in?
PIR insulation boards come in a variety of sizes to suit different applications. The standard size for most PIR boards is 2400x1200mm (8x4ft), but they come in varying thicknesses depending on the level of insulation required. Thickness options typically range from 25mm, 30mm, 40mm, 50mm, 60mm, 70mm, 75mm, 80mm, 90mm, 100mm, 120mm, 140mm, 150mm
The thicker boards generally offer better thermal insulation (low U-values).
What are the different brands of PIR boards?
- Celotex – One of the leading names in insulation, particularly in the UK. Known for its consistent quality, Celotex offers excellent thermal performance, with a typical lambda value of 0.022 W/mK. All their boards come with foil facings for improved moisture resistance and heat reflection, making them a reliable choice for both new builds and refurbishments.
- Kingspan – As a premium brand in the insulation world, Kingspan Therma is often seen as a leader in high-quality PIR boards. Kingspan offers the same impressive thermal efficiency as other brands, with a lambda value of 0.022W/mK. Their boards are foil-faced and boast exceptional fire and moisture resistance, making them suitable for a wide range of applications, including floors, walls, and roofs.
- Recticel – Recticel PIR Insulation Boards offer excellent thermal performance, with 0.022W/mK lambda value. Their boards are also foil-faced for enhanced moisture resistance, and they’re widely used in both residential and commercial projects.
- EcoTherm – EcoTherm offers high-quality PIR insulation with similar technical performance to other leading brands. Like others, Ecotherm PIR boards come with foil facing for improved durability and water resistance.
- Mannok – Formally known as Quinn is a growing name in the insulation industry. Their Therm PIR boards provide excellent thermal performance and versatility across different construction projects. Mannok’s boards also come foil-faced as standard and offer reliable performance for use on floors, walls and roofs.
- Xtratherm – Xtratherm is another prominent brand in the PIR insulation market, offering boards with a lambda value of around 0.022 W/mK, putting it on par with other top brands. Their boards are typically foil-faced for added thermal and moisture protection, and they’re suitable for a variety of construction projects, from domestic homes to large-scale commercial buildings.
What’s the difference between each PIR board?
At first glance, the decision might seem complicated, but if you dig into the technical, you’ll find that these products are almost identical in terms of performance. This leads to the big question:
Is there really any difference between them?
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The Technical side: Essentially Identical
When we break down the core technical properties of PIR boards from these brands, they’re virtually indistinguishable:
- Thermal Performance (Lambda Value): All of these brands offer a lambda value of around 0.022 W/mK, meaning they all provide excellent thermal insulation in a slim profile.
- Fire Performance: PIR boards from all these manufacturers meet similar fire safety standards, with most providing foil facings that offer enhanced fire resistance.
- Foil-Facing: Every one of the above-mentioned brands offers foil-backed boards, which provide moisture resistance and increase thermal efficiency.
- Sustainability: Sustainability initiatives have become standard across the board. Most of these manufacturers emphasise eco-friendly production processes and have Environmental Product Declarations (EPDs) to back it up.
So, from a technical standpoint, whether you choose Celotex, Kingspan, Recticel or any of the other brands, the product you’re getting will perform similarly in your building projects.
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The Price: No Real Difference
If you’re expecting price to be the deciding factor, think again. Across most suppliers, you’ll find that the pricing of these PIR boards remains consistent. While there might be slight fluctuations depending on local suppliers, overall, the price gap between brands is minimal. Most projects won’t see significant cost savings by choosing one brand over another unless a specific supplier offers a temporary deal or discount.
So, if the performance and price are virtually the same, how do you make a choice?
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Availability: which brand does your supplier stock?
The reality is, that most customers base their decisions on what’s readily available from their preferred supplier. Different suppliers tend to stock different brands, and they might not always carry all options at once. For most builders and contractors, this becomes the deciding factor: the brand you choose is often simply the one your supplier has on hand.
- Kingspan might be available from one distributor, while Celotex or Recticel might dominate another supplier's stock.
- Some suppliers have established relationships with certain manufacturers, meaning they’ll offer better support or delivery options for that specific brand.
If you have a reliable supplier who can deliver consistently and provide the insulation you need when you need it, that’s probably going to matter more than the brand name stamped on the boards.
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Brand familiarity and trust
Although the products are technically alike, some builders and contractors have a preferred brand based on personal experience or trust. Over time, contractors develop familiarity with specific brands and may stick to them for simplicity, especially if they’ve used them successfully on previous projects.
- Kingspan and Celotex are often seen as market leaders with established reputations.
- Recticel, Ecotherm and Xtratherm also have strong reputations but may be more regionally popular depending on where you’re sourcing your materials.
- Mannok, though lesser known outside certain regions, is highly trusted where it is widely used.
For most customers, this decision often boils down to who they know and trust to deliver, not because one product outshines another in terms of technical specs.
Final Thoughts: Practical factors lead the way
At the end of the day, while all the brands – Celotex, Kingspan, Recticel, Ecotherm, Xtratherm and Mannok – offer nearly identical products in terms of thermal performance, fire safety, and moisture resistance, the choice for most customers comes down to practical considerations:
- Which brand does your supplier carry?
- Which brand are you familiar with?
- Who offers the best availability and logistics for your project?
These are real-world factors that influence decisions in construction, where time, supply chains, and trusted partnerships matter just as much – if not more – than marginal differences in product features.
Ultimately, it’s safe to say that whichever PIR insulation brand you choose, you’ll be getting a product that delivers high-quality performance. The key is working with a supplier who can get the product to you efficiently, at a price you’re comfortable with.