I want to build a canopy on the pine end of my brick bungalow. I need it to be 10Metres long, and 4M deep, and covered with twinwall polycarbonate, however, I would like it to be a light structure (minimal CSA) so as to minimise interference with the view of the garden and beyond, so I'm thinking to use 3 or (4 at a maximum) upright supports, and a gutter beam which is not too deep. I'm minded to use steel rectangular hollow sections for the construction, cut to size, welding brackets or plates at appropriate joining points and having the whole lot hot galvanized before assembling on site using ss bolts.
My gut instinct is to use 50mm square tube for the uprights and concreted into the ground.
50mm square tube for the rafters (4M long @ 1M centres) 150x50 square tube for the gutter beam, supported by the vertical members to give 3.3M spans, (rafters providing lateral support).Stability would be provided as one end of the canopy would be built into a corner formed by the bungalow and an attached garage projecting 4M proud of the pine end, I have no experience of using this material beyond building a 1 ton trailer using 50mm square steel tube welded to form the structural chassis.
I understand that planning permission would not be required for this construction, however I would be inclined to use the services of a structural engineer to check and modify the proposed design as necessary. I would imagine that the structural calculations would be minimal for such a simple structure, however it is difficult to locate a structural engineer having the appropriate experience for this project. I'm located in N Shropshire.
Advice and/or constructive criticism welcomed.
Thanks in anticipation. Tom Williams