RIW Gas Seal HC

RIW Gas Seal HC


A 0.5 mm-thick, multi-layered, blended polyethylene membrane, for use where protection against ground gas and hydrocarbons are required.

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Combined ground floor damp proof membrane and hydrocarbon/ gas barrier.


A 0.5 mm-thick, multi-layered, blended polyethylene smooth sheet, typically used as a gas barrier and damp proof membrane in concrete floors below the slab or where additional protection from hydrocarbons and VOCs are required.

Features/ Benefits:

  • Hydrocarbon, methane, carbon dioxide, radon and VOC barrier.
  • Manufactured from virgin material, not recycled waste.
  • Separate damp proof membrane not required.
  • Robust jointing and sealing system.
  • High puncture resistance.
  • Welded joints possible.
  • Complies with latest code of practice as published by CIRIA and BRE.
  • Compliant with BS 8485:2015.


Combined ground floor damp proof membrane and hydrocarbon/ gas barrier.


A range of accessories are available (specified separately):

  • RIW Gas Seal GR DPC: Gas resistant damp proof course/ cavity tray, 450, 600 or 900 mm wide.
  • RIW Gas Seal Pipe Collar: Pre-fabricated ‘top-hats' for sealing around pipe penetrations. Available in 100, 130 and 160 mm diameters.
  • RIW Gas Seal Tape HC: Double-sided self-adhesive butyl tape, 100 mm wide, for sealing between overlaps in the membrane.
  • RIW Lap Tape RB: Self-adhesive polymer/ bitumen compound with polypropylene woven mesh, 75 mm wide, for sealing edges of lapped product.
  • RIW Pre-Formed Gas Cloaks: Pre-fabricated units for internal/ external corners and door reveals.

General information


Multi-layered, blended polyethylene

Uniclass 2015

Pr_25_57_65_60 Plastics sheetsPrimary
Specification data - Plastics sheets

Product Reference

RIW Gas Seal HC

Standard product features


Multi-layered, blended polyethylene.


0.5 mm.

Roll size:

2.0 x 50 m.


Black/ grey.

Side laps:

150 mm.

Technical properties:

  • Methane permeability (to BS ISO 15105-1): 0.13 ml/m²/day/atmosphere.
  • Tensile strength (to BS EN 12311-1): >550 N/50mm².
  • Tensile elongation (to EN 12311-1): 400%.
  • Tear resistance (to EN 12310-1): >300 N.
  • Water vapour transmission rate (to BS EN 1931): 0.14 g/m²/day.

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