Spec

Ultimate, gas, barrier, NF-500, hydrocarbon, PAH, VOC, VOCs, PAHs, hydrocarbons, BS8485, methane, carbon dioxide, radon, gas protection

Third party accreditation (BDA Agrement Certificate BAB-24-339-P-A-UK) 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 NF94 guidance for use in Type A and Type B membrane locations (non foil system) Conforms to the specification requirements of NHBC Amber 1 and Amber 2 applications Conforms to the specification requirements of BR 211:2023 UKCA UKNI CE to EN 13967:2012 Visqueen certified with Quality Management System ISO 9001:2015 Visqueen certified with Occupational Health and Safety System ISO 45001:2018 Visqueen certified with Environmental Management System ISO 14001:2015

Visqueen Ultimate Gas Barrier NF-500 is suitable for use in all types of buildings to prevent the ingress of harmful levels of volatile organic compounds (VOCs), methane, carbon dioxide and radon. The barrier can be positioned above or below reinforced cast in situ concrete floor slabs e.g. ground bearing, suspended or raft, or above precast suspended segmental subfloors, e.g. beam and block floor. The barrier can also be used as a high performance radon membrane and/or damp proof membrane. Where protection against VOCs or hydrocarbon contamination is required, the barrier system should be applied with welded joints. Radon, carbon dioxide, methane and VOC protection - NHBC NF94 guidance: Visqueen Ultimate Gas Barrier NF-500 when installed with either welded or taped joints (welded when used for VOC protection) complies with NHBC Foundation 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). In addition, Visqueen Ultimate Gas Barrier NF-500 when installed with welded joints complies with NHBC Foundation NF94 publication, Hazardous ground gas - an essential guide for housebuilders, 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 Visqueen Technical Services. The barrier is not intended for use where there is a risk of hydrostatic pressure.

When storing Visqueen Ultimate Gas Barrier NF-500 care should be taken to: - store in its original packaging; - avoid exposure to direct sunlight and high or low temperatures for prolonged periods of time; - store in a well-ventilated covered area to protect from rain, frost, humidity and mechanical damage; - store away from possible ignition sources; - store rolls of the barrier horizontally on a flat surface and not stacked. Care should be taken to avoid accidental damage to the product when handling on site. Care should be taken when handling the product in line with current manual handling regulations.

Visqueen Ultimate Gas Barrier NF-500 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 loose aggregates or other sharp protrusions, voids, projections or mortar deposits. The barrier can be cut with a sharp retractable safety knife or robust scissors. Hand rollers are required during lap joint formation and sealing membrane detailing. Typical hand rollers include 40mm silicone pressure roller and 6mm brass penny pressure roller. Consult the project specification to ensure the correct method of lap joint formation for the project is followed (welded or taped). Where protection against VOCs or hydrocarbon contamination is required, the barrier system should be applied with welded joints. Rolls of tape should be kept in a warm, dry location prior to use to ensure the tape is workable and can be more easily applied.

Installation of Visqueen Ultimate Gas Barrier NF-500 should be carried out by a competent contractor experienced with this type of product e.g. hold an NVQ Level 2 Diploma in substructure work occupations (Installation of Gas Membranes - Construction). The installation should be subjected to third-party validation in accordance with BS 8485:2015 +A1:2019 and CIRIA C735. Visqueen Ultimate Gas Barrier NF-500 should be loose laid on the substrate ensuring that the barrier sheet edges are aligned allowing adequate overlap for jointing between the sheets. The barrier can be laid either side facing upwards. The barrier lap area should be clean and dry at the time of jointing. The barrier has been designed to exhibit superior welding properties using hot wedge and hot air welding, therefore onsite welding of all lap joints is recommended. When hot air hand welding the lap joints, the joint should be overlapped by approximately 100mm and an approximate 35mm weld is normally achieved. During hand welding, the lap joints should be firmly compressed using a hand roller to ensure an adequate bond is achieved. When taping the lap joints, the joint should be overlapped by approximately 100mm and bonded with VisqueenPro Double Sided Jointing Tape (positioned approximately 25mm from the edge of the sheet) and sealed with Visqueen NF-150 Lap Tape. The lap joints should be firmly compressed using a hand roller during taping to ensure an adequate bond is achieved. Creating an effective gas barrier often requires complex three-dimensional detailing, such as around internal and external walls, corners, doorway thresholds, service pipes, party walls, and structural columns. Visqueen Detailing Strip (Pro or NF depending on the project specification) is gas resistant and can be used in place of the gas barrier to maintain continuous protection. The detailing strip lap joints should be firmly compressed using a hand roller to ensure an adequate bond is achieved. Visqueen Ultimate Preformed Units are also available. If the barrier is punctured or perforated a patch of the same material should be lapped at least 100mm beyond the limits of the puncture and, depending on jointing specification, either welded in position, or bonded with VisqueenPro Double Sided Jointing Tape (positioned approximately 25mm from the edge of the sheet) and sealed with Visqueen NF-150 Lap Tape. Alternatively, depending on jointing specification, a patch can be formed using Visqueen NF-Detailing Strip lapped at least 150mm beyond the extents of the puncture. Long periods of exposure to ultraviolet light will reduce the effectiveness of the barrier. The barrier should be covered by a protective layer e.g. Visqueen TreadGuard protection or other approved protection material, immediately after installation to prevent damage from following trades, ultraviolet light, etc. Care should be taken to ensure that the barrier is not punctured, stretched or displaced during or post installation. VisqueenPro Detailing Strip is also suitable for sealing detailing junctions and patch repairs, however when the gas protection measures are to conform with the requirements of NHBC NF94 guidance, please ensure acceptance by all stakeholders prior to use.

When Visqueen Ultimate Gas Barrier NF-500 is installed with taped lap joints, the air temperature should not be below 5°C or falling to prevent the risk of surface condensation affecting the tape adhesion. When ambient temperatures are above 25°C or rising, the barrier should be covered immediately after installation.

When used in accordance BS8485:2015 + A1:2019 a subfloor ventilation system or pressure relief may also be required. To assist build sequencing, Visqueen Ultimate Gas DPC is available for gas protection through the wall construction. For further information contact Visqueen Technical Office on 0333 202 6800. The information in this datasheet was correct at the time of publication. It is the user’s responsibility to obtain the latest version of the datasheet as it is updated on a regular basis. The information contained in the latest datasheet supersedes all previously published editions.

Refer to the Visqueen Ultimate Gas Barrier NF-500 safety datasheet (SDS).