Building the roof

Once the roof joists were in Nick laid 'firrings' on top which give the 'flat' roof a slight slop to help shed the water. Then 10cm of insulation board. Then 6mm of ply, then a breathable waterproof membrane. Should be ready to felt soon.

One area I have been thinking about and need to talk to the builder about is the void where the new joists join onto the joists from the existing house. This appears to be directly open to loft which i know from experience is very drafty and cold in the winter. Not much point putting in 10cm of insulation to have the space underneath open the draft loft! I guess its an  easy solution like stuff in some fibreglass, but its details like these that are keep me up at night!

Lastly we are still getting quotes and speaking to tilers. Tiling on 22mm chipboard as the builder would do appears to be a definite no, no. Mainly because chipboard has been known to turn to wheetabix if it gets moist - not an ideal tiling substrate! Laying 25mm ply to the whole area would be the best solution but would cost £1000 just for the ply board. After quite allot of research (there's so much contradictory evidence, and people regurgitating old wife's tales) I'm thinking the way to go will be get Nick to lay 22mm OSB board down, which is a little maybe double what the cheapest chipboard is, but its apparently far more robust and be more rigid for tiling on. Then Ditra isolation matting then the tiles. It's looking like it will end up costing me double what I had originally anticipated when I expected the floor was going to be constructed from a solid slab....

The lead guy turned up this morning to make all the flashing for the roof. He was a really nice chap. He said he had done the lead work on the domes at the Greenwich Observatory - so that can't be bad!