Keytec 400

Gas Barrier

Key features

  • Five layer process membrane
  • Exceeds DPM standards
  • Extremely low gas transmission
  • Gas barrier for methane, carbon dioxide and radon
  • Weldable with conventional hot air equipment
  • Aluminium foil core
  • Meets BS standards for DPC

Keytec 400 Gas Barrier:
Specification methane and co²

Keytec 400 gas membrane is loose laid to a prepared substrate. The membrane contains at least 15μ aluminium foil, reinforced with polyester multistrand scrim and encapsulated with polyethylene films. The puncture resistance has a CBR of at least 142N and maximum elongation of 3.3% with a minimum thickness of 0.46mm and a methane transmission of less than < 0.01cm³/m²/h. Keytec 400 is fully hot-air welded and tested for peel and sheer within the application.


Scrim reinforced polyethylene and aluminium.

Keytec 400 can be used in a variety of applications including the protection againt Methane, Radon, CO² gases and also Hydrocarbon vapours
Material specification CE MARK to EN 13967
PropertyUnitValueTest method
Unit weightg/m²415ASTM D1505
Thicknessmm0.46ASTM D5799
Tensile strengthk/N/m9.47ASTM D 6693.04
Methane transmission cm³/h/m²less than 0.005EN 1062-6 (1999)
Oxygen transmissionNILEN 1062-6 (1999)
Moisture transmissiong/m²/dayless than 0.01EN 1062-6 (1999)
Radon improvement factor500-1
Puncture resistanceN142.1 ASTM D4833
Determination of Resistance to RootsPASSDD CEN/TS 14416:2005
  • Standard detail 1

  • Standard detail 2

  • Standard detail 3

  • Standard detail 4

Product detail

J40 Flexible sheet tanking /
damp proof membranes

110. Hardcore beds

Blind with not less than 50mm of soft sand or pulverized fuel ash and consolidated to provide a smooth bed free of sharp projections.

120. Polyethylene damp proof membrane / gas barrier:

Manufacturer and reference:
Keytec 400 by Keytec Geomembranes. Telephone 0116 262 9106

  • Thickness / gauge: O.46mm
  • Methane transmission less than 0.005cm³/h/m²
  • Tensile MD 9.47kn/m
  • Moisture transmission less than 0.01g/m²/day

The membrane is loose laid to the formation with 100mm overlaps welded by hot air fusion at seams and terminated at the edge of the outer leaf of the structure.

Care must be taken to ensure that the gas membrane is not punctured prior to the casting of the concrete floor slab or screed.

All service entries are sealed with proprietary top-hat sections and heat welded to the gas barrier or adhesive methane membrane in the case of multi-ducts. (Keyflex GMA)

310. Workmanship generally

Materials must be applied with care to provide a completely gas impervious and damp proof membrane.

360. Junctions with projecting DPCs / cavity trays

Adjoining surfaces must be clean and dry.
Projecting DPCs/ cavity trays: Lap, fully bond and seal with sheeting.

  • Laps (minimum): 100mm
  • Bonding/sealing: Manufacturers' recommendations

370. Pipes, ducts and cables

Preformed collars are recommended for the purpose by the membrane manufacturer.

  • Sealing: Fully bond to penetrations and sheeting
  • Completed junctions: Impervious