I
iDIY
I’m not sure how to explain this but here goes 
I am a few rows of block below full height on a building in the back garden. It will have a pent/flat roof and 2 sides and a back constructed in dense block with a 90mm cavity.
The 4th or Front face has 500mm relief walls at either side, continuing the 90mm cavity, the rest of that 4th will have a 5m long upvc door / window unit made and fitted. Because it is 5m wide and the roof timbers will be supported above the window I got a structural engineer to calculate the size of RSJ required and he came back with 178x102 19kg with a top timber plate bolted on to secure the roof joists.
All pretty straight forward..
However, I’m a bit unsure of if it should rest on the inner leaf or outer leaf of the relief walls at each end, as being 102 wide it’s one or the other. I know that ‘normally’ you would support roof joists on a plate bolted to the top of an inner leaf. But if I put the rsj on the inner leaf there is nothing to fix the top of the upvc unit to?
any thoughts welcome.
I am a few rows of block below full height on a building in the back garden. It will have a pent/flat roof and 2 sides and a back constructed in dense block with a 90mm cavity.
The 4th or Front face has 500mm relief walls at either side, continuing the 90mm cavity, the rest of that 4th will have a 5m long upvc door / window unit made and fitted. Because it is 5m wide and the roof timbers will be supported above the window I got a structural engineer to calculate the size of RSJ required and he came back with 178x102 19kg with a top timber plate bolted on to secure the roof joists.
All pretty straight forward..
However, I’m a bit unsure of if it should rest on the inner leaf or outer leaf of the relief walls at each end, as being 102 wide it’s one or the other. I know that ‘normally’ you would support roof joists on a plate bolted to the top of an inner leaf. But if I put the rsj on the inner leaf there is nothing to fix the top of the upvc unit to?
any thoughts welcome.
