I'm building a small conservatory and just getting to the stage to put the warm flat roof on. I was going to stop the joists on the inner skin of thermalite blocks and take the cavity insulation up to meet the insulation on the roof which would make a continues thermal barrier. Then build up the outside skin to the hight under the roof deck taking the roof deck over the cavity and outside blocks and then fit a fascia guttering etc. Not sure if BC will accept this or how to fix the edge of the deck to the outside skin. Could I just screw it down? Thanks.
It should be ok but you need to ask your BCO. What do your drawings show? By the by, warm flat roof and conservatory don't go together and connies don't need BRA: is it an extension?