Powerbase Multigas Barriers

Powerbase Multigas 300 reinforced methane radon and CO2 gas barrier membrane

  • Multilayer reinforced LDPE gas barrier membrane for radon, methane and CO2
  • Independently tested to ISO 15105-1
  • Compliant to BS 8485:2015 (Multigas 300)
  • CE Marking
  • High tear and impact resistance
  • Available in rolls for joining on site
  • Also acts as a damp proof membrane
  Multigas 300 Multigas 500
Weight 270gsm 370gsm
Gas permeability

Methane 0.041 ml/day/m2/ATM
CO2: 0.195 ml/day/m2/ATM

Methane 0.41ml/day/m2/ATM
CO2 0.195ml/day/m2/ATM
Tensile strength MD 290N/50mm
XD 300N/50mm
MD 370N/50mm
XD 347N/50mm
Colour Silver/Green Silver/Green
Standard size 2.0 x 50m 2.0 x 50m



CE-ISOQARPowerbase Multigas Barrier Membranes are multilayer reinforced LDPE aluminium composites with exceptionally low methane, radon and CO2 permeation rates. Aluminium is known for its gas barrier qualities and it – along with the LDPE outer layers – also makes Powerbase gas barriers very effective damp proof membranes. Their high levels of tear and impact resistance are a product of long-term research and development combined with high quality manufacturing processes.

Powerbase Multigas Barrier Membranes have CE Marking for "Flexible sheets for waterproofing –Damp proof sheets (EN 13967: 2012) and gas resistant barrier membrane". The membranes are independently tested to ISO 15105-1 and are compliant to BS 8485. 

Industrial Textiles & Plastics Ltd is ISOQAR Quality Assured and certified to ISO 9001

Powerbase Multigas Barrier Membranes are supplied as rolls for joining on site as standard.

ITP's Geomembranes Team provides technical support and customer-specific service. Contact them on +44(0)1347 825201 or email powerbase@itpltd.com.



Methane, radon and CO2 are naturally occurring gases which can be harmful in high concentrations.

Radon is commonly found over granite formations whereas methane and carbon dioxide are produced as a result of the decomposition of organic matter such as made ground or natural deposits such as coal, peat or silt.

Where these are present, Powerbase Multigas Barriers Membranes provide effective protection. They are suitable for sites requiring NHBC Green, Amber 1 and Amber 2 gas protection measures.


Typically, an impermeable barrier is designed in the foundations of the building over a highly permeable ventilation layer. Hazardous gases migrate up through the soil and collect under the membrane in a sump from where they are vented and safely dispersed into the atmosphere. The principal function of the gas barrier membrane is to prevent harmful gases from entering the building through cracks, construction joints and service openings in the floor slab. The membrane should cover the whole plan area of the structure to all external faces in order to seal the ground slab as well as any cavity walls and voids in hollow concrete block work.

Powerbase Multigas Barrier Membranes can be joined on site with hot-air/hot-wedge welding or taped with Powerbond Double-Sided Jointing Tape. It is important to note that the shelf life of self-adhesive products is limited: usually between 6 months and 1 year when protected from direct sunlight and ambient temperatures above 30°C.

Certification and Compliance

CE Marking is required for many products. It

  • shows that the manufacturer has checked that these products meet EU safety, health or environmental requirements
  • is an indicator of a product’s compliance with EU legislation
  • allows the free movement of products within the European market

Powerbase Multigas Barrier Membranes have been tested for use as "flexible sheets for waterproofing –Damp proof sheets (EN 13967: 2012) and gas resistant barrier membrane" to ISO 15105-1.

BS 8485:2015 is the code of practice for the design of protective measures for methane and carbon dioxide ground gases for new buildings.