- 23 Feb 2016
- Reaction score
I have a low pitched roof, about 20 degrees, clad with fibre cement slates on battens on untearable breather felt. I formed a 50mm air gap by fixing 50mm x 25mm battens to the inside of the rafters and cladding the underside with plastic sheeting and then hardboard. There is a considerable amount of water running down the underside of the rafters, enough to fill several buckets in just over two weeks. The water only appears to come in when it is raining. I have stripped the roof and the only other thing I have found is that some of the glass fibre insulations appears to have been close to the underside of felt. Could this just be condensation?