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A high performance gas membrane for use in situations where resistance to methane, carbon dioxide and/ or radon gases is required. It is generally used within construction applications, predominantly within the foundation design. The multilayer 0.4 mm thick membrane includes an ultralow permeability aluminium foil core encapsulated between a number of additional low density polyethylene (LDPE) layers and a reinforcing grid to form a single sheet membrane.

Features and benefits:

  • Excellent resistance properties with low permeability to ground gases including methane, carbon dioxide and radon.
  • Provides additional damp proofing protection to the structure (no requirement for a separate DPM).
  • Reinforced membrane construction with high resistance to both puncturing and tearing.
  • Complies with relevant industry codes and guidance including CIRIA and BS 8485:2015+A1:2019.

Standard product features


Reinforced low density polyethylene with an aluminium foil core.


Green/ silver.


0.4 mm.


370 g/m².

Roll size:

2 x 50 m.

Technical properties:

  • Tensile strength (to EN 12311-1/2): Machine direction (MD): 370 N/50mm. Cross direction (CD): 347 N/50mm.
  • Nail tear resistance (to EN 12310-1): MD: 295 N. CD: 341 N.
  • Elongation (to EN 12311-2): MD: 22%. CD: 16%.
  • Methane gas permeability (to EN ISO 15105-1 and ASTM D1434): 0.041 ml/day/m²/atm.
  • Carbon dioxide gas permeability (to EN ISO 15105-1 and ASTM D1434): 0.195 ml/day/m²/atm.
  • Water vapour resistance (to EN 1931 and EN 12572): 0.01 gsm/day.
  • Temperature range: -40 to 70ºC.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-65-50/325 Plastics sheets

Product specification

An important note about specifying



Cordek Ltd


+44 (0)1403 799600

Product reference

Tri-Gas Membrane

Manufacturer details

Spring Copse Business Park,
West Sussex, RH13 0SZ
Tel +44 (0)1403 799600
Fax +44 (0)1403 791718
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