Important Information: For all updates and Celotex announcements since June 2017, please see the links below...  See more

Declared lambda values - Read more >

5000 Class 0 testing - Read more >

Rainscreen cladding & RS5000 - Read more >

Celotex FI5000

Premium performance flooring insulation solution, suitable for concrete slab, beam and block, suspended timber and underfloor heating flooring applications.

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IMPORTANT: We have recently identified a compliance issue relating to our calculation and testing of the lambda value of products in our 4000 and 5000 range and the Crown-Bond and Crown-Fix products within Crown Flat Roofing range. Due to this issue, the suspension of the 5000 range will continue and now includes the FI5000 and GD5000 products. Materials relating to this product are for information only.

Please use the link below to read our full statement regarding declared lambda:

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Celotex FI5000 is a premium performance flooring insulation solution, suitable for a range of flooring applications including concrete slab, beam and block, suspended timber and underfloor heating applications.


  • Board size: 1200 x 2400mm
  • Thickness : (Currently Suspended) 75 - 125mm
  • Lambda: 0.021 W/mK
  • Facer: Innovative Composite Facer with built-in VCL

Celotex FI5000 provides thermal performance benefits and has been designed with installation efficiency in mind. Featuring a super low lambda of 0.021W/mK, FI5000 achieves compliance to UK Building Regulations with better U-values and thinner solutions. 

Celotex FI5000 combines best in class PIR insulation with an innovative composite facer featuring a built-in vapour control layer (VCL), enabling direct screed, without the need for an additional separating layer. FI5000 features an enhanced compressive strength value of ≥175 kPa making it the ideal solution for a range of flooring applications.

You can also find out more about high performance upstand insulation Celotex US4000 for concrete slab and beam and block flooring applications when Celotex FI5000 is installed.

Plus, that's not all. Using our comprehensive U-value Calculator we can offer you detailed flooring U-value Calculations that ensure you are achieving regulatory compliance. Click here to start calculating!

We also offer quick and easy SAP calculations through our Energy Assessments Celotex Service. For more information or to request a free quote, contact our experienced team today.