Frequently asked question

Do you have install a Breather Membrane with your Glasroc ‘X’ Sheathing Board

Approved Document C states that a breather membrane should be used over the face of the sheathing board. Whilst this is a guidance document and therefore not the only means of compliance with Building Regulations, it should be for the building designer to determine if a particular construction requires a breather membrane or not. In terms of water vapour resistance, Glasroc X Sheathing Board falls within the definition of a breather membrane (0.46MNs/g) in relation to this performance aspect as defined within BS 5250.