MemTech Void Vent 25


Ground Gas ProtectionMemTech’s Void Vent 25 offers a passive venting solution which facilitates the dispersal and dilution of dangerous gases.  MemTech’s Void Vent 25 has been specially designed to provide for high levels of air and/or gas flow.

MemTech’s Void Vent 25 is incomparable for its protection against dangerous gases and chemicals.  Optimised for maximum strength and performance.

  • Lightweight and easy to install
  • High gas flow capacity
  • Creates a de-pressurisation zone for collection of ground gases

Ground Gas Barrier Protection Void VentMemTech Void Vent 25 is a cuspated HDPE (High Density Polyethylene) membrane with a geotextile filter/separator.  Void Vent 25 has been designed to be installed with the geotextile filter side of the product to be in contact with the ground to allow for air and/or gas flow.  Void Vent 25 is available in either a 25mm or 40mm depth.

MemTech Void Vent 25 provides a passive means of ventilation  for ground gas protection when used in conjunction with:

  • MemTech Liquid Gas Barrier ‘LGB’
  • MemTech M1
  • MemTech R1
  • MemTech Titon

MemTech Void Vent 25 complies with the latest codes of practice (BRE, CIRIA and NHBC).

Ground Gases and Contaminates

  • Hydrocarbons
  • Methane (CH4)
  • Carbon Dioxide (CO2)
  • Radon (Rn)
  • Volatile Organic Compound (VOCs)

MemTech Void Vent 25

  • Suitable for new and existing structures
  • Independently tested by UKAS
  • BBA Certified
  • High resistance to puncture
  • Complies with BRE211:2015 and BS8485:2015


Memtech Void Vent 25 is installed underneath the Memtech gas membrane to provide passive ventilation of ground gas in accordance with BS 8485:2015.

Ground Gas ProtectionIt is either laid to the entire footprint or in 450mm or 900mm wide strips at designated intervals to provide appropriate levels of venting depending on CS level, Building type and building width. The Memtech Void Vent is linked to Memtech Vent boxes which provide the link to external atmosphere. These are installed on opposing sides of the building and each vent box provides 18000mm2 ventilation area.

Design and Specification

Brownfield sites or sites that have previously been used for commercial or industrial purposes will require ground gas protection.

When designing a gas protection solution consideration should be applied to the gas protection solution, point scoring system.

Our dedicated Technical Team are able to offer superior structural waterproofing and ground gas knowledge and take into consideration all relevant regulations when specifying a suitable ground gas barrier system.

Product code:DMS404

If you'd like more information on any of our products, call 01992 523 523 today to speak to one of our experts