Whats the regulation re span on flat roofs?

Question

I have to build a flat roof - 10.55 meter wide and 4.55 meter deep - Any advise re construction?

Answer 1

span your joists the shortest distance, 200x50 tannalised timber should be big enough, but check with building regs. run 2 rows of noggins, preferably herringbone strutting. when you cut your firring pieces don't cut them down to nothing, run them down to about 12mm, this will stop them splitting near the ends. allow for good ventilation under your soffit, and make sure you fit a drip batten over your gutter. get someone who knows what they are doing to do your lead work, this has to be right.