DIY Doctor UK DIY Forums

Hi, hope someone out there can help. Want to build a flat roofed gazebo. The size is 4.5m x 4.5m. I know that I need joists of 220 x 47 [9x2] to span at 400mm centres. But I want to connect these at each end to wooden joist spanning two pillars. What I cant seem to find is what size should the wooden joists be to hold what will be 10 internal joists.

In this situation the bearing joists are usually double the thickness of the spanning joists. Two spanning joists bolted together is the usual method of achieving this. Good luck and do let us know how you get on.