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Visqueen Ground Gas Collection and Venting Systems

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Visqueen

Ground gas collection and venting system.

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+44 (0) 333 202 6800 Website

Application

For gas collection and venting applications.

Description

Ground gas collection and venting system.


System components:

  • Gas collection (venting hardcore layer): Supplied by others.
  • Gas collection (collection membrane): Visqueen Gas Vent Mat.
  • Gas collection (collection pipework): Visqueen Gas Venting VT Pipework.
  • Depressurization sumps (type): Visqueen Radon Sump.
  • Depressurization sumps (base and fill): Supplied by others.
  • Gas proof membrane: Visqueen Gas Barrier.
  • Venting and outlets (pipework): Visqueen Adjustable Z Vent.
  • Venting and outlets (external outlets): VisqueenPro Gas Vent Box or Visqueen Airbrick or Visqueen Gas Vent Bollard.
  • Venting and outlets (fans): Supplied by others.

General information

Color

Black

Finish

Laminated

Guidance for specification option:

Visqueen Gas Vent Mat.

Smooth

Guidance for specification option:

Visqueen Gas Barrier.

Metallic

Guidance for specification option:

VisqueenPro Gas Vent Box.

Material

Polyethylene

Guidance for specification option:

Visqueen Radon Sump.

Visqueen Gas Barrier.

Low density polyethylene (LDPE)

Aluminium

Guidance for specification option:

Visqueen Gas Barrier.

Foil

Guidance for specification option:

Visqueen Gas Barrier.

Steel

Guidance for specification option:

VisqueenPro Gas Vent Box.

Shape

Other

Length

Bespoke

Width

Bespoke

Height

Bespoke

Warranty description

-

Manufacturer guidance

See manufacturer's insurance document for warranty details. Consult manufacturer for further information.

Uniclass

Ss_15_10_33_34 Ground gas collection and venting systemsPrimary

CAWS

D21/42 Wall vent outlets

D21/395 Ground-level vent outlets

Specification data - Ground gas collection and venting systems

Gas collection

-

Venting hardcore layer

Supplied by others.

Guidance for specification option:

Consult manufacturer for details.

Collection membrane

Visqueen Gas Vent Mat.

Guidance for specification option:

A geocomposite void former comprising a cuspate high-density polyethylene (PE-HD) core bonded to a nonwoven polypropylene geotextile filter membrane.


  • 25 mm thick and supplied in rolls 0.9 x 50 m.
  • Large format rolls - rapid installation.
  • Cost effective - less contaminated soil to be removed compared to pipe and gravel systems.
  • Used in specifications to BS 8485:2015 + A1:2019 - system achieves between 0.5 and 1.5 points.
  • Full range of system components provides various methods of exhausting gases to atmosphere.
  • Rectangular.
  • 50000 x 900 x 25 mm (L x W x H).
  • Black coloured.

Collection pipework

Visqueen Gas Venting VT Pipework.

Depressurization sumps

-

Type

Visqueen Radon Sump.

Guidance for specification option:

A prefabricated plastic sump to provide a central collection point, or to be part of a series of sumps located under a ground floor slab.


  • All pipe work connecting to the sump should be fully sealed using the Visqueen radon membrane jointing system.
  • It links gas collection pipes and provides ventilation to atmosphere for radon gas under the floor of the building.
  • It should be located as close to the centre of the building as possible.
  • Circular.
  • 700 x 700 x 250 mm (L x W x H).

Base and fill

Supplied by others.

Guidance for specification option:

Consult manufacturer for details.

Gas proof membrane

Visqueen Gas Barrier.

Guidance for specification option:

A multi-layer reinforced polyethylene membrane with an integral aluminium foil. For ease of identification on site Visqueen Gas Barrier is coloured blue on one side and silver on the reverse. The barrier combines strength and performance with flexibility and easy installation.


  • BBA approved.
  • Complies with the methane gas transmission rate, mass per unit area and thickness requirements of BS 8485:2015 + A1:2019 - industry standard for methane and carbon dioxide protection.
  • Low permeability to methane, radon and carbon dioxide.
  • Approved for use in NHBC Amber 2 applications.
  • Multi-layer reinforced LDPE membrane with aluminium core.
  • High puncture and tear resistance.
  • Rectangular.
  • 50000 x 2000 mm (length x width).
  • Blue and silver coloured.

Venting and outlets

-

Pipework

Visqueen Adjustable Z Vent.

Guidance for specification option:

Visqueen Adjustable Z Vents are manufactured from black polypropylene and are designed to provide a clear airflow passage to the underfloor void. 


  • Functional solution for exhausting ground gases from underfloor voids.
  • Integral grille which prevents movement of vermin through vent. 

External outlets

-

Wall

VisqueenPro Gas Vent Box.

Guidance for specification option:

A gas venting system that will safely disperse harmful gases into the atmosphere and reduce the risk of rainwater entering the void. 


  • Comprised of a galvanised steel base with a 110 mm pipe inlet and adjustable feet for leveling purposes and to secure the box within the concrete surround.
  • Versatile.
  • Tested to BS EN 1433:2002 - suitable for loads up to 12.5 tonnes.
  • Heel safe lids.
  • Lid locking mechanism provides security and allows for maintenance.
  • System allows for water management, reducing the risk of rainwater entering the void.
  • Each vent box provides a free air flow capacity of 20148 mm². 
  • Rectangular.
  • 530 x 123 x 112 mm (L x W x H).
  • Grey coloured.

Visqueen Airbrick.

Guidance for specification option:

Visqueen Airbricks are manufactured from UV stabilized polypropylene and are available in terracotta and black. The airbrick replaces an external masonry brick. It incorporates a front mounted louvered grill to permit airflow while blocking out wind driven rain and prohibiting large insects from gaining access.


  • Functional solution for exhausting ground gases from underfloor voids.
  • Integral grille which prevents movement of vermin through vent. 

Visqueen Gas Vent Bollard.

Guidance for specification option:

Visqueen Gas Vent Bollard is a 110 mm diameter stainless steel or plastic vent bollard with a total height of 1400 mm of which between 800–900 mm is positioned above external ground level. The vent bollard provides a free air flow capacity of 25000 mm² (stainless steel) or 13200 mm² (plastic).


  • Used for all ground gas venting applications including volatile organic compounds (VOCs).
  • Aesthetic finish - rust proof.
  • High free air flow capacity - reduces number of units required.
  • Slotted venting design - eliminates need for a sub-base soakaway.
  • 8 kg weight (stainless steel); 1.48 kg weight (plastic).

Roof

VisqueenPro Gas Vent Box.

Guidance for specification option:

A gas venting system that will safely disperse harmful gases into the atmosphere and reduce the risk of rainwater entering the void. 


  • Comprised of a galvanised steel base with a 110 mm pipe inlet and adjustable feet for leveling purposes and to secure the box within the concrete surround.
  • Versatile.
  • Tested to BS EN 1433:2002 - suitable for loads up to 12.5 tonnes.
  • Heel safe lids.
  • Lid locking mechanism provides security and allows for maintenance.
  • System allows for water management, reducing the risk of rainwater entering the void.
  • Each vent box provides a free air flow capacity of 20148 mm². 
  • Rectangular.
  • 530 x 123 x 112 mm (L x W x H).
  • Grey coloured.

Visqueen Airbrick.

Guidance for specification option:

Visqueen Airbricks are manufactured from UV stabilized polypropylene and are available in terracotta and black. The airbrick replaces an external masonry brick. It incorporates a front mounted louvered grill to permit airflow while blocking out wind driven rain and prohibiting large insects from gaining access.


  • Functional solution for exhausting ground gases from underfloor voids.
  • Integral grille which prevents movement of vermin through vent. 

Visqueen Gas Vent Bollard.

Guidance for specification option:

Visqueen Gas Vent Bollard is a 110 mm diameter stainless steel or plastic vent bollard with a total height of 1400 mm of which between 800–900 mm is positioned above external ground level. The vent bollard provides a free air flow capacity of 25000 mm² (stainless steel) or 13200 mm² (plastic).


  • Used for all ground gas venting applications including volatile organic compounds (VOCs).
  • Aesthetic finish - rust proof.
  • High free air flow capacity - reduces number of units required.
  • Slotted venting design - eliminates need for a sub-base soakaway.
  • 8 kg weight (stainless steel); 1.48 kg weight (plastic).

Fans

Supplied by others.

Guidance for specification option:

Consult manufacturer for details.

Sustainability data

Material

Polyethylene

Guidance for specification option:

Visqueen Radon Sump.

Visqueen Gas Barrier.

Low density polyethylene (LDPE)

Aluminium

Guidance for specification option:

Visqueen Gas Barrier.

Foil

Guidance for specification option:

Visqueen Gas Barrier.

Steel

Guidance for specification option:

VisqueenPro Gas Vent Box.

Literature

Visqueen Product Guide 2022

Visqueen Product Guide 2022