Use in cavity walls with formaldehyde fumes

Foam insulating materials which give off formaldehyde fumes either when used or later in normal use, may be used to insulate the cavity in a cavity wall where there is a continuous barrier which will minimise, as far as practicable, the passage of fumes into the building. BS 8208 gives guidance on factors to be considered when assessing the suitability of existing masonry external cavity walls for filling with thermal insulants.