3 floor modern townhouse. Top floor is partially in roof space with inset dormer windows.
After heavy rain storms we keep getting waterstains on the ceilings of the floor below the dormers.
Had a roofer out twice. He has been all over the roof and put new, longer leading under tiles, and sides of dormer, sealed every conceivable space. There's only a tiny roofspace, but he/we have been up there looking for gaps/leaks and can't find anything.
BUT we are still getting watermarks.
It's not the old ones coming through, as we stain-painted those, but the new ones are new and damp.
Only happens every few months after particualrly heavy rain.
Any ideas? A friend said it might be something to do with excess water in the sills of the dormers.
I DO think it's something to do with the dormers, as the stains are directly beneath them.