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Radbar Flexible Hydrocarbon Membrane 1.3 x 20m

£248.00 Ex VAT
£297.60 Inc VAT

Highly effective flexible hydrocarbon membrane that protects buildings from methane, carbon dioxide, radon and VOCs as well as moisture. Suitable for brownfield sites.

Flexible Hydrocarbon Barrier Membrane 

RADBAR flexible Hydrocarbon membrane is a tri-polymer membrane that provides an effective barrier against radon, VOCs, Methane, Carbon Dioxide and Hydrocarbon gases. It’s designed to protect properties whilst providing the flexibility to make installation easier. 

This black Hydrocarbon Barrier Membrane can be used above or below the slab in concrete ground floors. It is manufactured from specific polymers to have excellent chemical resistance including to volatile organic compounds (VOCs). 

The membrane has undergone extensive testing to ensure its integrity under challenging conditions. This gives occupants peace of mind.  

Uses of Radbar Flexible Hydrocarbon Membrane 

This hydrocarbon gas-resistant membrane is ideal for sites that have been formerly used as:

  • Brownfield sites - suitable in brownfield applications that are affected by hydrocarbons
  • Coalfields
  • Landfill sites
  • Industrial sites 

These previous uses mean that the ground can contain chemicals and volatile liquids. 

Important note: This membrane is not suitable when subject to hydrostatic pressure.

Installing a Flexible Hydrocarbon Membrane

The outstanding flexibility of this hydrocarbon barrier membrane makes it easy to install.

You should install this hydrocarbon membrane just before you lay the screed. 


The flexible hydrocarbon membrane should only be installed on a blinded or smooth surface. Ensure that the surface has a smooth finish with no projections or voids - this applies to both concrete slabs and brick and blockwork.

Start by cleaning and then drying all surfaces to make sure they are free of grease, dust, mortar and any other debris. 


Roll out the hydrocarbon membrane with the embossed surface uppermost, making sure it is aligned with the surface. When the membrane is laid below the concrete slab, it should be loose-laid to accommodate any small movements.  


Where overlaps are required, ensure that the membranes overlap by a minimum of 150mm. Where they overlap, make sure they are dirt, dust and moisture-free. These joints can then be bonded together with Radbar Hydrocarbon Double-sided Jointing Tape and sealed with Radbar Hydrocarbon Single-sided Tape. Apply as much pressure as possible to the area being jointed. 


If ground gases are present, then you need to consider ventilation during construction. During construction, a stand-by Radon sump can be installed with the pipework capped off close to the building outside. 

A fan can be added to the pipe at a later date to activate the system if radon levels are found to be high. Suspended floors with a solid concrete base also allow the option to retrofit a vented system with a sump as either a passive (no fan) or active (with fan) system. This would be more disruptive to the homeowner than a pre-installed system at construction stage. The Hydrocarbon membrane is compatible with vented systems.

Laying a Screed 

The hydrocarbon resistant membrane should be covered by a screed or other protective layer as soon as possible after installation. The screed should be at least 55mm thick across the entire membrane. This will help protect it. 

Important note: The membrane can be installed in all normal site conditions, provided that the air temperature is not below 5°C to prevent the risk of surface condensation. The membrane installation should be subject to third-party independent validation, in accordance with BS 8485 : 2015. 

Read our guide to installing gas membranes

Radbar Hydrocarbon System

The continuity of the gas & hydrocarbon protection must extend over the footprint of the building, and the gas membrane must be sealed to a gas-resistant damp-proof course.

Related gas membrane products:

  • Radbar Double-sided Jointing Tape — for joints and lap
  • Radbar Single-sided Overlap Tape.
  • Radbar Top Hat Unit — to seal service entry points to the membrane
  • Radbar gas sump — underfloor ventilated sump
  • Radbar preformed corner details and cloaks — prefabricated details

Permagard - Providing Solutions. Inspiring Confidence.

If you have any questions about gas membranes and how to install Flexible Hydrocarbon membranes contact our experts. We’re happy to provide free technical advice on 0117 982 3282.


  • BBA-approved flexible hydrocarbon membrane
  • Made from an engineered tri-polymer thermoplastic membrane
  • Resistant to water and water vapour
  • Resistant to underground gases — the product is capable of restricting the ingress of radon, methane and carbon dioxide into the structure
  • Resistance to chemicals — the product is chemically resistant to VOCs
  • Very high puncture and tear resistance - on a smooth or blinded surface it will not be damaged by foot or site traffic
  • Highly durable — under normal service conditions will restrict the ingress of radon, methane, carbon dioxide and VOC vapours during the lifetime of the flooring construction in which it is installed
  • Suitable for hot welding.