We recently moved into a bungalow and the roof needs some tlc. Think two old chimney stacks that were never removed, a couple of sky lights (currently only covered with tarp) that need installing not too mention the felt is pretty old and bare. There are a few rotten boards but we've just discovered in a few places from inside the house that there is no insulation. So, what we thought as replacing the felt or GRP.. is now turning into a conversation about a warm deck. Is it ok to install the warm deck over the existing felt roof? Will any moisture in the existing boards and felt be trapped and lead to more problems like damp and mold in the future? All opinions and thoughts warmly received. Thank you