What membrane do I need to use under timber cedar shingles?
A cedar shingle roof needs to ‘breathe’ to achieve its optimum lifespan. For the best performance an underlay is recommended for all shingle roofs whether domestic or commercial.
Shingle roofs over 22 degrees
For roofs over 22 degrees an air permeable type underlay can be used. This should meet the requirements of Annex A of BS 5534:2003+A1:2010.
Care should be taken with warm roof applications to follow current building regulations and individual specifications can be determined in conjunction with the insulation manufacturer.
Counter battens and battens should be used to create a vented space and again the underlay should meet the requirements of Annex A of BS 5534:2003+A1:2010.
Low pitched shingle roofs
A low pitched roof, that is roof with a pitch between 14-22 degrees, requires a water impermeable, vapour permeable underlay. This should meet the requirements of Annex A of BS 5534:2003+A1:2010. If it’s a warm roof counter battens should be used to create a vented space.