Pitch a garage roof

[OBBob]

Hi All

Is there a simple way to pitch a roof on a garage without using prefab trusses? I have lots of old timber to use up and a good solid load bearing wall down each side and the back.

I could run a ridge down the centre and use rafters but the front end is open with double doors, so I couldn't have a column (width of opening ~2600mm) length of garage 6700mm, 42deg pitch roof, tiled, no ceiling.

There must be a way to design this but the standard tables don't really seem to cover this sort of design. Really I just wanted to use all my old timber if possible.

[toecutter]

Hi All

Is there a simple way to pitch a roof on a garage without using prefab trusses? I have lots of old timber to use up and a good solid load bearing wall down each side and the back.

I could run a ridge down the centre and use rafters but the front end is open with double doors, so I couldn't have a column (width of opening ~2600mm) length of garage 6700mm, 42deg pitch roof, tiled, no ceiling.

There must be a way to design this but the standard tables don't really seem to cover this sort of design. Really I just wanted to use all my old timber if possible.

Also something to consider is maybe you should install a roof beam in the centre to stop the walls from being pushed out by the roof load on the rafters.
You could still support the ridge board at the opening with a stub column on a lintel as well as a stub column on the roof beam to the ridge.

[OBBob]

Also something to consider is maybe you should install a roof beam in the centre to stop the walls from being pushed out by the roof load on the rafters.

Thanks for the response.

Do you mean a beam spanning from the middle of the top plate of each wall ... like a collar tie sitting right at the base of each rafter?

You could still support the ridge board at the opening with a stub column on a lintel as well as a stub column on the roof beam to the ridge.

OK, so if I understand teh first comment correctly then the span of the ridge would be halved and be a continuous rather than single span.

But ... how do you calculate the lintel size ... is it then a Roof Load Width of both rafter spans added together i.e. 3600mm in my case as the rafters would be 1800mm long?

[toecutter]

Do you mean a beam spanning from the middle of the top plate of each wall ... like a collar tie sitting right at the base of each rafter? YES

note: All drawings compiled using mans 2nd best friend

[OBBob]

I can't see any of your drawings ... just red crosses.

[toecutter]

weird
pm me your email address and ill email them

[OBBob]

Hi All

Can someone give me some clarification on what this beam should be designed as? I'd call it a strutting beam. I was planning to use 4 of them along the 6m length of the shed to support the ridge beam. I have some nice old 155 x 45mm hardwood I wanted to use but the way I calculate it with 60kg/m roof load they wouldn't be suitable for that span.

I am on the right track?

[thebuildingsurv]

If your getting a permit for it, you will need an engineers design because the roof pitch is outside the framing code. If you collar tie each rafter then the ridge is not loadbearing, you then will not have to prop the ridge and the lintel at the front would then not be very big at all. there is a table for lintels in non load bearing walls.

[OBBob]

Good points, thanks. I think I'm over thinking it!!