I have to design a shallow mono-pitch roof (around 20 degrees) for my proposed extension. The roof is to have a 4m long ridge above an existing party wall, and a span of 5m across the back of the house. The roof space is to be completely open as a feature. May be cold or warm roof. It will be OSB/felt boarded under the tiles due to the low pitch. Roughly, my inclination is to have 2 purlins about 2x8, and rafters 2x6 at 400mm spacings. The tie to the party wall and house wall would be joist hangers on 2x8s fixed with expansion bolts. Does this sound reasonable, under/over specced, or am I totally ignorant ? BCO will proably want structural calc, I know. Simon.
- posted
18 years ago