When you’re looking to upgrade your home’s thermal efficiency, PIR (Polyisocyanurate) insulation boards are often the go-to choice. They are lightweight, easy to cut, and offer some of the best thermal performance per millimetre on the market.
But with big names like Celotex, Kingspan, and Mannok all available at Next Day Insulations, how do you choose the right one for your project? In this guide, we break down the key differences to help you decide.
1. Celotex: The Versatile All-Rounder
Celotex is perhaps the most "famous" name in UK insulation. Their GA4000 and XR4000 ranges are staples for floor, wall, and roof applications.
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Best For: General purpose use in residential extensions and renovations.
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Key Advantage: Incredible availability and a wide range of thicknesses (from 12mm up to 200mm).
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Thermal Conductivity: Typically 0.022 W/mK, which is the industry standard for high-performance PIR.
2. Kingspan: The Premium Specialist
Kingspan is often seen as the "premium" choice, particularly their Kooltherm and Therma ranges. While often slightly higher in price, they offer specialized solutions for specific builds.
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Best For: High-spec projects where space is at a premium or specific building regs (like fire or acoustic performance) are strict.
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Key Advantage: Their K100 series can offer thermal conductivity as low as 0.018 - 0.021 W/mK, meaning you can use a thinner board to achieve the same U-value as competitors.
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Niche Products: They offer dedicated boards for pitched roofs (TP10) and cavity walls (TW50).
3. Mannok: The Value Powerhouse
Formerly known as Quinn Therm, Mannok has rapidly become a favorite for builders looking for professional quality without the "brand name" markup.
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Best For: Large-scale projects, new builds, and budget-conscious DIYers.
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Key Advantage: Excellent cost-to-performance ratio. Mannok PIR boards match the thermal conductivity of Celotex (0.022 W/mK) but often come in at a more competitive price point per sheet.
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Reliability: They are fully certified and widely accepted by building inspectors across the UK.
Comparison Table: At a Glance
| Feature | Celotex (GA4000/XR4000) | Kingspan (Therma/K-Series) | Mannok (PIR) |
| Thermal Conductivity | 0.022 W/mK | 0.018 - 0.022 W/mK | 0.022 W/mK |
| Typical Use | Universal (Floors/Walls/Roofs) | High-spec / Thin profiles | General Construction |
| Price Point | Mid-Range | Premium | Budget-Friendly |
| Ease of Install | Excellent | Excellent | Excellent |
Which Should You Choose?
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Choose Celotex if… You want a reliable, tried-and-tested board that is easy to find and meets all standard UK building regulations.
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Choose Kingspan if… You have very limited space (e.g., a thin wall or narrow rafters) and need the absolute lowest thermal conductivity possible to meet your U-value targets.
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Choose Mannok if… You are insulating a large area and want the best possible value for money without sacrificing thermal performance.
Get It Delivered Tomorrow
No matter which brand you choose, the most important part of any build is keeping it on schedule.
At Next Day Insulations, we stock a massive range of PIR Insulation Boards from all these leading brands. With our reliable delivery, you can get your materials on-site exactly when you need them.