What are breather membranes and why are they required?

https://www.labcwarranty.co.uk/technical-blog/guide-to-breather-membranes?utm_content=303690337&utm_medium=social&utm_source=linkedin&hss_channel=lcp-2384972

Breather membranes are made from a variety of materials and they have two primary functions. Firstly they can provide temporary  weather protection to the structure prior to the application of cladding, and secondly they allow water vapour from inside the wall construction to pass outward through the wall.

Both of these functions stop moisture being trapped within the wall construction and thus preventing the framed structure from rotting (timber frame) or corroding (LGSF).

Read more here on the LABC website for further information including warranty information.