What membrane should i 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.

 

Disclaimer - The information shared in this blog is correct at the time of publication. Guidance, standards, and best practices may change over time, so if you’d like further clarification or the latest updates, please get in touch with the Marley Technical Advisory Team, who will be happy to help.