Visqueen Class B FR Vapour Check is used in buildings where an air and vapour control layer (AVCL) is required that achieves a reaction to fire classification B - s1, d0 to BS EN 13501-1:2018. The membrane is used to reduce the risk of interstitial condensation occurring within the structure as well as improving the airtightness of the building.

The membrane restricts the passage of warm, moist air within the building from permeating into the floor, wall or roof structure and is designed to be installed on the warm side of the structure.

For conformity with the reaction to fire classification, usage of Visqueen FR Double Sided Vapour Tape or Visqueen FR Single Sided Vapour Tape must not exceed 11% of the area of the Visqueen Class B FR Vapour Check.

Care should be taken by the Designer to ensure suitability for applications other than those stated above. Visqueen Class B Vapour Check should be approved by all stakeholders prior to use.

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

Approvals and Standards

• Achieves a reaction to fire classification A2 - s1, d0 to BS EN 13501-1:2018
• Air leakage to BS EN 1026:2016
• CE UKCA UKNI Mark EN 13984:2013
• Quality Management System ISO 9001:2015
• Occupational Health and Safety System ISO 45001:2018
• Environmental Management System ISO 14001:2015

System Components

Visqueen FR Vapour Tape.

Preparation

When bonding Visqueen Class B FR Vapour Check to a substrate, e.g. metal or timber studwork, the surface should be smooth, clean, dry and free from dust or sharp protrusions.

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

Installation

Visqueen Class B FR Vapour Check should be installed in accordance with the recommendations of BS 5250:2021 Management of moisture in buildings - code of practice. The membrane should be installed on the warm side of the insulated structure, with care being taken to ensure that all laps, penetrations and abutments are sealed. The membrane should be continuous in order to ensure optimum airtightness and vapour control performance.

Visqueen FR Double Sided Vapour Tape is available for bonding the membrane to substrates such as metal or timber studs or noggings.

All joints in the membrane should be lapped by minimum 75mm (some warranty providers require minimum 100mm) and sealed with Visqueen FR Single Sided Vapour Tape applied centrally over the lap. To aid formation laps should be made over a solid substrate e.g. located over studs or noggings.

Ensure membrane continuity at the junction of horizontal and vertical substrates. Seal abutments with Visqueen FR Single Sided Vapour Tape applied centrally over the junction. Failure to suitably connect the barrier to other building elements will severely reduce airtightness and vapour control performance.

For conformity with the reaction to fire classification, usage of Visqueen FR Single Sided Vapour Tape or Visqueen FR Double Sided Vapour Tape must not exceed 11% of the area of the Visqueen Class B FR Vapour Check.

Ensure the membrane is not damaged in service due to residual heat from light fittings. The membrane should not be subjected to gravity forces (unsupported) such as on the underside of roof decks or the underside of floor structures, and should be suitably mechanically secured to ensure that it remains in position during service.

Visqueen air and vapour control layers (AVCLs) do require permanent mechanical fixing, normally achieved by over-boarding the AVCL with a plasterboard or other construction board.

Care should be taken to prevent the AVCL from becoming punctured, stretched or displaced when installing plasterboard or other construction board over the installed AVCL.

Usable Temperature Range

It is recommended that Visqueen Class B FR Vapour Check and all associated system components should not be installed below 0°C.