Thanks for the quick reply.
Yes, they do appear to be fitted correctly. While I've just been checking, I noticed a pool of water on top of the felt under the first row of tiles, although it doesn't seem to be wet underneath the felt at all.
Hello
I was hoping someone can help. I've recently had a small extension built. We've had a lot of rain recently, some of which seems to have leaked through the roof. I've called the builder back to look at that, but I've also noticed the brickwork from the outside seems damp on both corners...