Comments re old roof make up.

Having recently replaced the old 1995 flat roof on an extension, I forgot I took some pics. I had wondered, at the time, about the make up of the roof

This is the roof in question


It was made up of 18mm ply on 4 X 2's, then 25mm of celotex type material laid across the 4 x 2's ...



Then several layers of felt. Problem was that some of the insulation had compressed, allowing water to pool and rot my barge boards and leak down the sides into the room below.


Is/Was it usual to felt on top of this celotex type stuff?

No concerns just interested.

Yip and it is still used although nowadays the cellotex is backed with blockboard so that it can be fixed using nails rather than the old method of fitting it using hot tar. If you redo the roof using this system a word of advice, keep off it once its finished and make sure you put a decent run on it i.e. raise the taper pieces so that no pooling can occur.