Kingspan TP10 vs Celotex XR4000: PIR Boards Compared
Kingspan Thermapitch TP10 and Celotex XR4000 (now sold as Sopratherm XR4000) are the two PIR boards most often named on drawings for pitched roofs, walls and floors at thicker build-ups. They share the same declared thermal conductivity, so at the same thickness they do the same thermal job. The real differences are price, the thicknesses you can get and how each one is delivered. This guide compares them using the manufacturers’ published data and our prices as of 16 October 2026.
The two boards in brief
- Kingspan Thermapitch TP10 is Kingspan’s multi-purpose PIR board for pitched roofs, floors and walls, with a PIR core and composite foil facings. We stock it from 25mm to 150mm. See all Kingspan insulation boards.
- Celotex XR4000 is Celotex’s thicker PIR board for pitched roofs, floors and walls where you want a low U-value from a single layer. Soprema bought Celotex and the board is now made and sold as Sopratherm XR4000. It has a PIR core with low-emissivity composite foil facings on both sides. We stock the 120mm (XR4120) and 150mm (XR4150) boards. See the full Celotex (Sopratherm) range.
Side-by-side comparison
| Kingspan Thermapitch TP10 | Celotex XR4000 (Sopratherm) | |
|---|---|---|
| Core | PIR | PIR |
| Facings | Composite foil | Low-emissivity composite foil, both sides |
| Thermal conductivity (λ) | 0.022 W/mK | 0.022 W/mK |
| Board size | 2400 × 1200mm | 2400 × 1200mm |
| Compressive strength | 120 kPa (at 10% compression) | ≥140 kPa (CS(10\Y)140) |
| Reaction to fire | Euroclass F | Euroclass F |
| BBA certificate | 14/5133 | 25/7318 and 25/7329 |
| Thicknesses we stock | 25–150mm | 120mm and 150mm |
| How we sell it | Per sheet | Per sheet |
Figures are from each manufacturer’s datasheet and BBA certificates, which are linked from the product pages.
Same thickness, same R-value
Thermal resistance (R-value) is the thickness divided by λ. Because both boards declare 0.022 W/mK, they publish the same R-values: 5.45 m²K/W at 120mm and 6.80 m²K/W at 150mm. So if your U-value calculation works with 120mm of TP10, it works with 120mm of XR4000 too, as long as your specification or Building Control allows an equivalent product. To check what thickness you need, use our PIR U-value calculator.
Price at the same thickness
Prices per 2400 × 1200mm sheet (2.88m²), ex VAT, correct as of 16 October 2026:
| Thickness | R-value (m²K/W) | Kingspan TP10 | Celotex XR4000 | Difference per sheet |
|---|---|---|---|---|
| 120mm | 5.45 | £64.33 | £43.07 | £21.26 |
| 150mm | 6.80 | £78.28 | £51.88 | £26.40 |
At 120mm and 150mm, XR4000 is the cheaper board per sheet. For a typical loft conversion using 40 sheets of 150mm, that difference comes to more than £1,000 ex VAT before delivery.
Delivery is where it gets more complicated
- Kingspan TP10 goes with our other insulation, plasterboard and drylining: free delivery across England with a minimum order of £400 ex VAT. Orders usually come on a Moffett lorry with forklift offload, so someone needs to be there to receive them.
- Celotex (Sopratherm) is delivered separately with its own rules: minimum Celotex order £400 ex VAT, £40 delivery under £550 ex VAT and free from £550 ex VAT. Other items in your basket don’t count towards these amounts.
So for small orders, the £40 Celotex delivery charge can cancel out the saving. For larger orders over £550 ex VAT of Celotex, XR4000 usually works out cheaper overall at 120mm and 150mm. If you need thicknesses other than 120mm or 150mm, or you’re mixing PIR with plasterboard, studs and other boards for a £400 free-delivery order, TP10 is often the simpler choice.
Which should you choose?
- Choose Celotex XR4000 for 120mm or 150mm in bigger quantities, especially when a Celotex order on its own reaches £550 ex VAT, or when your drawings specify XR4000.
- Choose Kingspan TP10 if you need any thickness from 25mm to 140mm, want everything on one free delivery with your other insulation and drylining, or your specification names Kingspan.
- Want the cheapest 0.022 board? Recticel Eurothane GP and Mannok PIR declare the same λ. See our Celotex vs Kingspan vs Recticel vs Mannok comparison.
How many sheets do I need?
Each sheet covers 2.88m². Divide your area by 2.88, round up and add around 10% for cutting. Our insulation calculator does this for you. For the right thickness by application, see what thickness of PIR insulation do I need?
Not sure which board your job needs? Call our team on 03330 908479 for expert advice, Monday to Friday. We deliver to England only.