Visqueen Ultimate HC Blok is a 0.5mm thick, chemically resistant co-extruded volatile organic compound barrier and gas barrier. It is coloured gold on the upper surface and white on the reverse. The product is supplied in single wound rolls (not folded), 2.44m x 41m.

Radon, carbon dioxide, methane, and VOC protection – NHBC NF94 guidance:

Visqueen Ultimate HC Blok when installed with either taped or welded joints (welded only for VOC protection) 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). Visqueen Ultimate HC Blok also complies with this guidance when installed with welded joints in Type B membrane locations in 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
• Storage and Handling
• Preparation
• Installation
• Usable Temperature Range
• Additional Information

Approvals and Standards

• Third party accreditation (BDA certificate BAF-18-051-P-A-UK)
• Complies with NHBC Foundation’s NF94 guidance for use in Type A and Type B membrane locations
• Complies with CIRIA C748:2014
• 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
• 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 13967:2012
• Quality Management System ISO 9001:2015
• Occupational Health and Safety System ISO 45001:2018
• Environmental Management System ISO 14001:2015

System Components

• Visqueen Ultimate Double Sided Jointing Tape, 100mm x 15m
• Visqueen GR Lap Tape, 150mm x 10m
• Visqueen Ultimate Top Hat Units
• Visqueen Preformed Units - contact technical for more information on 0113 2455450 (option 2) or send a message to [email protected]
• VisqueenPro Detailing Strip, 300mm x 10m, 500mm x 10m

Storage and Handling

Visqueen Ultimate HC Blok 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 Ultimate HC Blok should be installed on a smooth continuous surface free from irregularities such as voids or protrusions e.g. grouted beam and block floor, 50mm thick sand blinding, or smooth concrete blinding. The membrane can be cut with a sharp retractable safety knife or robust scissors.

Installation

Visqueen Ultimate HC Blok should be loose laid on the substrate with the gold 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 Ultimate Double Sided Jointing Tape and sealed with Visqueen GR 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 Ultimate 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 Ultimate Double Sided Jointing Tape and sealed with Visqueen GR 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 Ultimate 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 Ultimate Double Sided Jointing Tape and sealed with Visqueen GR Lap Tape. Alternatively 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.

Detailed drawings can be downloaded from the "Data Sheets" tab further above, for details on:

• HC-01 Edge Detail Suspended Slab
• HC-02 Edge Detail Suspended Slab
• HC-03 Edge Detail Suspended Slab
• HC-04 Edge Detail Raised Floor
• HC-06 Internal Wall House To Garage
• HC-07 Stepped Slab Gas Protection
• HC-09 Internal Cavity Wall
• HC-10 Robust Detail Internal Cavity Wall
• HC-11 Level Threshold Raised Ground Level
• HC-12 Mobility Threshold
• HC-21 Rev 0 Edge Detail Ground Bearing Slab
• HC-51 Service Pipe Top Hat
• HC-52 Steel Column Sealing

Usable Temperature Range

It is recommended that Visqueen Ultimate HC Blok and all associated system components should not be installed below 5°C.

Additional Information

• When used in accordance with CIRIA C748:2014 or BS8485:2015 + A1:2019, a subfloor ventilation system or pressure relief maybe required
• 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 HC-01
• Visqueen Ultimate Preformed Top Hat Units should be used at service pipe penetrations see HC-51
• For internal and external corners Visqueen Ultimate Preformed Corner Units are available see PFU-553
• To seal around steel columns use VisqueenPro Detailing Strip see HC-52

For additional detailing information contact Rawlins Technical on 0113 2455450 (option 2) or send a message to [email protected]