PermaSEAL Self-Adhesive Radon & Methane Gas Membrane 1m x 20m

Self-Adhesive Radon and Methane Gas Membrane

PermaSEAL Self-Adhesive Gas Membrane provides reliable protection against radon, methane and water ingress in below-ground structures. It creates a continuous gas-resistant barrier that helps prevent harmful ground gases from entering basements, foundations and other occupied areas.

This makes it particularly suitable for new-build and existing structures on contaminated land, former industrial sites and other locations where radon or methane may be present. By combining gas protection and external waterproofing in one membrane, it can simplify the construction build-up and reduce the need for separate systems.

The membrane consists of a tough, cross-laminated high-density polyethylene film bonded to a highly adhesive, polymer-modified bitumen compound. It is puncture and tear resistant, flexible enough to bridge minor cracks and immediately gas-tight and waterproof once correctly installed and detailed.

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Uses of PermaSEAL Gas Membrane

PermaSEAL Self-Adhesive Gas Membrane is intended for external, positive-side applications where protection against radon, methane and water ingress is required. Typical uses include:

• Gas protection on contaminated or previously developed land
• Radon protection in areas identified as being at risk
• External basement and cellar waterproofing
• Foundation walls and below-ground structures
• External structural waterproofing
• External vertical walls
• Podium decks
• Flat and ventilated roofs

The membrane is compatible with steel and most metals and can be applied to prepared mineral substrates, precast concrete and ICF when used with the appropriate primer.

Why Protect Against Radon and Methane?

Radon and methane can migrate through the ground and enter buildings through foundations, floors, service penetrations and construction joints. A correctly installed gas-resistant membrane creates a continuous barrier that helps prevent these gases from entering basements and other occupied areas.

PermaSEAL Self-Adhesive Gas Membrane combines gas protection and external waterproofing in one tough, flexible system. This makes it particularly suitable for contaminated land, former industrial sites and other locations where radon or methane may be present.

• Combined protection: guards against radon, methane and water ingress within a single membrane system.
• Tough and flexible: the cross-laminated HDPE film is puncture and tear resistant and can bridge minor cracks.
• Reliable sealing: the high-tack self-adhesive backing helps create secure joints, overlaps and detailed areas.
• Quick installation: the membrane is cold-applied and requires no flame, heating or curing period.
• Immediate protection: once correctly installed and detailed, the membrane is waterproof and gas-tight.

Tested Gas Resistance

• Radon permeability: 5.7 × 10^-12 m²/s
• Methane permeability: less than 5 cc/m² per 24 hours per atmosphere

Installation

To create an effective gas-resistant barrier, all sheets, overlaps, corners, penetrations and junctions must be carefully sealed and rolled. Pay particular attention to pipes, changes of direction and wall-to-floor junctions, as gaps or poorly sealed details can compromise the continuity of the system.

Preparation

Start by making sure your substrate is clean, free of dust and previous coatings, smooth and dry. A primer will be required for porous substrates - we recommend PermaSEAL Self-Adhesive Bitumen Primer. Closely follow the instructions to guarantee correct application.

Application

PermaSEAL Self Adhesive Gas Membrane needs to be applied downwards. This means you start with the roll at the highest point and make your way down. Overlap the membrane by a minimum of 50mm on edges and 150mm on top joins.

Once rolled out in position, press the membrane against the substrate. You should pay particular attention to corners, edges and overlaps. Use a pressure roller on all joints and overlaps to seal the membrane and remove any trapped air.

PermaSEAL - Complete Solutions. Made Possible.

When it comes to water and gas protection, you can trust PermaSEAL membranes. Our PermaSEAL range brings together technical excellence and high quality at low trade prices. For specification advice or technical guidance, speak to our team on 0117 982 3282.