Visqueen Gas Barrier is a multi-layer reinforced polyethylene gas barrier with a 20 micron aluminium foil. The barrier is coloured blue on the upper surface and silver on the reverse. The product is supplied in single wound rolls (not folded), 2m x 50m.

Radon, carbon dioxide, and methane protection - NHBC NF94 guidance:

Visqueen Gas Barrier when installed with either taped or welded joints complies with NHBC Foundation’s NF94 publication, Hazardous ground gas - an essential guide for housebuilders, in Type A membrane locations in precast suspended segmental subfloors and reinforced cast in situ concrete floor slabs (ground bearing, suspended or raft). For site or zone characteristic gas situations of CS4 and above, contact Rawlins Technical on 0113 2455450 (option 2) or send a message to [email protected].

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• Approvals and Standards
• System Components
• Preparation
• Installation
• Usable Temperature Range
• Additional Information

Approvals and Standards

• Third party accreditation (BBA 13/5069)
• Complies with the methane gas transmission rate, mass per unit area and thickness requirements of BS 8485:2015 + A1:2019
• Suitable for all Characteristic Gas Situation (CS) ground gas regimes
• Complies with NHBC Foundation’s NF94 guidance for use in Type A membrane locations
• Conforms to the specification requirements of NHBC Amber 1 and Amber 2 applications
• Conforms to the specification requirements of BR 211:2023
• CE Mark EN 13967:2017
• Quality Management System ISO 9001:2015
• Occupational Health and Safety System ISO 45001:2018
• Environmental Management System ISO 14001:2015

System Components

• VisqueenPro Double Sided Vapour Tape, 20mm x 50m
• VisqueenPro Single Sided Vapour Tape, 75mm x 15m
• VisqueenPro Single Sided Vapour Edge Tape, 150mm x 15m

Preparation

Visqueen Gas Barrier should be installed on a smooth continuous surface e.g. grouted beam and block floor, a compacted blinding layer e.g. 50mm thick sand blinding, or smooth concrete blinding. The substrate should be free from irregularities such as voids or protrusions.

The barrier can be cut with a sharp retractable safety knife or robust scissors.

When installing the membrane in demanding site conditions, use Visqueen GR Lap Tape in place of Visqueen Gas Resistant Foil Lap Tape.

Installation

Visqueen Gas Barrier should be loose laid on the substrate with the blue side up so as to avoid sunlight glare.

The barrier should be clean and dry at the time of jointing. It should be overlapped by at least 150mm, bonded with Visqueen Pro Double Sided Jointing Tape and sealed with Visqueen Gas Resistant Foil Lap Tape. Alternatively lap joints can be heat welded to achieve an effective seal. The overlap in the barrier is typically 100mm and when hand welding, a 35mm weld is normally achieved.

When hand welding, a roller must be used.

Airtight seals should be formed around all service entry points. Visqueen Preformed Top Hat Units are recommended for sealing service entry pipes. The base of the top hat and the upstand should be bonded using VisqueenPro Double Sided Jointing Tape and sealed with Visqueen Gas Resistant Foil Lap Tape. The upstand should be secured with the supplied jubilee clip. Alternatively VisqueenPro Detailing Strip can be used to seal service entry points. The upstand should be secured with a jubilee clip.

Forming an effective barrier to gases may give rise to complex three-dimensional detailing where, it is recommended Visqueen Preformed Units are used e.g. corners. Alternatively VisqueenPro Detailing Strip can be used to seal awkward junctions. If the barrier is punctured or perforated a patch of the same material should be lapped at least 150mm beyond the limits of the puncture and bonded with Visqueen Pro Double Sided Jointing Tape and sealed with Visqueen Gas Resistant Foil Lap Tape.

vAlternatively a patch can be formed using VisqueenPro Detailing Strip and lapped at least 150mm beyond the extents of the puncture.

Long periods of exposure to ultraviolet light will reduce the effectiveness of the membrane. The membrane should be covered by a protective layer immediately after installation to prevent damage from following trades, ultraviolet light, etc. Care should be taken to ensure that the membrane is not punctured, stretched or displaced when applying a screed or final floor covering. A minimum thickness of 50mm screed is recommended. When reinforced concrete is to be laid over the barrier the wire reinforcements and spacers must be prevented from puncturing the barrier. Where there is a high risk of potential damage, the barrier should be covered with Visqueen TreadGuard protection, screed or other approved protection material before positioning the reinforcement.

See "data sheets" tab further above to download detailed drawings on:

• Gas Barrier
  • GB-01A Barrier Above Slab, Beam & Block Floor, External Masonry Cavity Wall
  • GB-02A Barrier Above Slab, Beam & Block Floor, External Masonry Cavity Wall
  • GB-03A Barrier Above Slab, Beam & Block Floor, External Masonry Cavity Wall
  • GB-04 Edge Detail Raised Floor
  • GB-06 Internal Wall House To Garage
  • GB-07 Stepped Slab Gas Protection
  • GB-09A Barrier Above Slab, Beam & Block Floor, Masonry Party Wall
  • GB-10 Robust Detail Internal Cavity Wall
  • GB-12 Mobility Threshold
  • GB-13A Barrier Above Slab, Beam & Block Floor, External Light Gauge Steel Frame Wall
  • GB-14 Barrier Above Slab, Beam & Block Floor, External Light Gauge Steel Frame Wall
  • GB-15 Barrier Above Slab, Beam & Block Floor, Internal Masonry Wall
  • GB-16 Barrier Above Slab, Beam & Block Floor, Internal Masonry Wall Built Off Floor
  • GB-21A Barrier Below Slab & Insulation, Cast In Situ RC Ground Bearing Slab, External Masonry Cavity Wall
  • GB-29B Barrier Below Slab, Cast In Situ RC Slab, External Light Gauge Steel Frame Wall
  • GB-51 Service Pipe Top Hat
  • GB-61 Barrier Above Slab, Beam & Block Floor, External Masonry Cavity Wall at Telescopic Vent Location
  • GB-62 Barrier Below Slab & Insulation, Cast In Situ RC Ground Bearing Slab, External Masonry Cavity Wall
  • GB-63 Barrier Above Slab, Beam & Block Floor, External Light Gauge Steel Frame Wall
  • GB-81 Service Pipe Detailing Using VisqueenPro Detailing Strip, Step By Step
  • GB-82 Steel Column Detailing Using VisqueenPro Detailing S
• Membrane Joining
  • JD-08 Hand Welded Lap Joint Detail
• Tanking Systems
  • TGB-05 Rev 0 Typical Lift Pit Detail With Gas Protection
  • TGB-06 Rev 0 Typical Lift Pit Detail With Gas Protection
  • TGB-52 Rev 0 Typical Edge Detail With Gas Protection - Ring Beam

Usable Temperature Range

It is recommended that Visqueen Gas Barrier and all associated system components should not be installed below 5°C.

Additional Information

• When used in accordance BS8485:2015 + A1:2019 a subfloor ventilation system or pressure relief maybe required
• Where hydrocarbon or VOC contamination is present use Visqueen Ultimate HC Blok or Ultimate GeoSeal gas protection systems
• To assist build sequencing, Visqueen Ultimate Gas DPC is available for gas protection through the wall constructions
• For suspended beam and block floor detailing see GB-01
• For internal and external corners Visqueen Ultimate Preformed Units should be used see PFU-553
• To seal around steel columns use VisqueenPro Detailing Strip see GB-52
• For additional detailing information, contact Rawlins Technical 0113 2455450 (option 2) or send a message to [email protected]