4 x 12.5m - Yellow 500mu C/F Roll

Visqueen Low Permeability Gas Membrane

Features and benefits

BBA certified - third party accreditation
Complies with NHBC Amber 1 - suitable for low gas risk NHBC housing sites
Flexible - easy to detail and install on site
Supplied centre folded - reduces the risk of cracks in screed and limits creases
Multi functional - also acts as a radon and damp proof membrane
Dual jointing methods - lap joints can be taped or heat welded

Product description

Visqueen Low Permeability Gas Membrane is a robust co-polymer thermoplastic gas membrane, 0.5mm thick, yellow in colour
and supplied 4m x 12.5m in a center folded roll.

Approvals and standards

Third party accreditation (BBA 13/5069)
Conforms to the specification requirements of NHBC Amber 1 applications
Conforms to the specification requirements of BR 211:2015
CE Mark EN 13967:2017
Quality Management System ISO 9001:2015
Occupational Health and Safety System ISO 18001:2007
Environmental Management System ISO 14001:2015

Usage

Visqueen Low Permeability Gas Membrane is suitable to prevent the ingress of harmful levels of ground gases for housing
applications where NHBC are the warranty provider and the site has been classified as Amber 1. In this application, the membrane
is used above a precast suspended segmental ground floor system, for example a beam and block floor.
The membrane can also be used as a high performance radon membrane and/or damp proof membrane positioned within the
ground floor construction either above or below the structural floor.
The product is not intended for use where there is a risk of hydrostatic pressure.

System components

Visqueen Pro Double Sided Jointing Tape, 50mm x 10m
Visqueen Gas Resistant Foil Lap Tape, 75mm x 50m
Visqueen Top Hat Units
VisqueenPro Detailing Strip, 300mm x 10m, 500mm x 10m
Visqueen TreadGUARD 300, 2m x 75m
Visqueen TreadGUARD 1500, 1m x 2m

Storage and handling

Visqueen Low Permeability Gas Membrane should be stored horizontally, under cover in its original packaging.
Care should be taken when handling the product in line with current manual handling regulations.

Preparation

Visqueen Low Permeability Gas Membrane should be installed on a smooth continuous surface free from irregularities such as
voids or protrusions e.g. grouted beam and block floor.

In radon applications, the membrane should be installed on a smooth continuous surface or 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 membrane can be cut with a sharp retractable safety knife or robust scissors.

Installation

Visqueen Low Permeability Gas Membrane should be loose laid on the substrate. The membrane 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 Foil Lap Tape. In demanding site conditions seal lap joints with Visqueen Ultimate GR Lap Tape.

Alternatively lap joints can be heat welded to achieve an effective seal. Welded lap joints can be less than 150mm provided the
joint integrity is not compromised.

Airtight seals should be formed around all service entry points. Visqueen Preformed Top Hat Units should be used for sealing
service entry pipes. The base of the top hat and the upstand should be bonded using Visqueen Pro Double Sided Jointing Tape
and sealed with Visqueen Foil Lap Tape. The upstand should be secured with the supplied 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 Visqueen Pro Detailing Strip can be used to seal awkward junctions.

If the membrane 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 Foil Lap Tape. Alternatively a
patch can be formed using Visqueen Pro Detailing Strip and lapped at least 150mm beyond the extents of the puncture.

The membrane should be covered by a protective layer as soon as possible after installation to prevent damage e.g. from
following trades. 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 membrane the wire reinforcements and spacers must be prevented from puncturing the membrane. Where there is a high risk
of potential damage, the membrane should be covered with Visqueen TreadGuard protection, screed, or other approved
protection material before positioning the reinforcement.

Usable temperature range

It is recommended that Visqueen Low Permeability Gas Membrane and all associated system components should not be installed
below 5°C

Additional information

When used in full radon protection areas, a Visqueen Radon Sump or subfloor ventilation system maybe required.

Where ground gas protection is required to BS 8485:2015 + A1:2019, use Visqueen Gas Barrier system.

To assist build sequencing, Visqueen Zedex CPT DPC is available for gas protection through masonry wall constructions.

For suspended beam and block floor detailing see LPGM-01.

Visqueen Preformed Top Hat Units should be used at service pipe penetrations see LPGM-51.

For internal and external corners Visqueen Preformed Corner Units should be used see PFU-553.

To seal around steel columns use Visqueen Pro Detailing Strip see LPGM-52.

The product is recyclable and categorised under LDPE recycling code 4.