Celotex TB4000

Celotex TB4000 is an easy to install polyisocyanurate (PIR) insulation board with excellent thermal performance, featuring a low emissivity foil facing. Available in thicknesses from 20mm to 40mm, it can be considered for floor, wall and roof applications.

Product Image
U-value Calculator
Start your U-value calculation >
Use the calculator

Product Features


  • Lightweight 2400 x 1200mm boards
  • Low emissivity foil facing
  • BBA certified – certificate 17/5405 (Pitched Roof, Dry Lining, Floor Insulation)


Fire Classification

Euroclass F Reaction to Fire classification, according to BS EN 13501-1. Products with this level of classification are not provided with a rating for smoke emission.

Product Specification

Thickness (mm) Length (mm) Width (mm) Lambda Value (W/m.K) R-Value (m².K/W)
20 2400 1200 0.022 0.90
25 2400 1200 0.022 1.10
30 2400 1200 0.022 1.35
35 2400 1200 0.022 1.55
40 2400 1200 0.022 1.80

Product Benefits


  • Thermal Performance - Excellent thermal performance with a thermal conductivity of 0.022 W/m.K, reducing the thickness of insulation required to hit the target U-value.
  • High Performance Facer - Low emissivity foil facing provides improved thermal performance in sealed cavity air spaces, improving the achievable U-value.
  • Easy to Install - Celotex boards are light and rigid assisting with ease of transportation, handling and fitting.
  • BBA Certified - Celotex TB4000 has been assessed by the BBA as fit for use in defined roof, wall and floor applications if installed, used and maintained as set out in the certificate. Please read the BBA certification page for full details and restrictions.


Key Considerations

When using Celotex TB4000, you need to satisfy yourself that use of the product meets all relevant national Building Regulations and guidance as well as local, national and other applicable standards relevant for your construction or application, including requirements in relation to fire and applicable height restrictions.
Please refer to the following product documents:

Celotex TB4000 should not be used in the external walls of buildings over 11 metres in height. Recent changes to Building Regulations mean that only non-combustible insulation or insulation of limited combustibility should be used in buildings of that height.