5m long span to support tile roof on shed/workshop

[moconnell]

Hi guys im getting further along with my shed/workshop build and now now realised that i need to think about load support if i want to do a 'proper' tiled roof as i have a 5 m span.

Currently i have a 5 meter span between my gable ends ive got a sold oak 8x2 on tied in to my 150mm wide oak beams in the centre of the ends. Building is approx 5x4 metres.

Ive send 3 emails out to structural engineers locally to ask for a consultation but none seem to want to know as maybe too small a job?

I just want to know if i need to add more timber to make it strong enough or if i need some steel in there...

Anyone got any advice or rule of thumb i can apply to this structure (that doesnt technically need building regs). Ideally i wanted to use old clay pan tiles or slates on this 20degree pitch roof...

This gives an idea on it

Thanks
Matt

 

[cdbe]

If it's a vaulted roof that's miles too small, if it's a conventional roof with rafters and ceiling joists it's not a structural component so will be fine.

 

[moconnell]

Yeah i wanted vaulted..so ive got to replan...current idea is since gable rafters will be 10cm square beams i might run 2 more either 8x2 or 4x4 across the lenth from mid gable rafter to gable rafter maybe giving me effectively 3 times what i have. Does that seem ok?

 

[Dereekoo]

Yeah i wanted vaulted..so ive got to replan...current idea is since gable rafters will be 10cm square beams i might run 2 more either 8x2 or 4x4 across the lenth from mid gable rafter to gable rafter maybe giving me effectively 3 times what i have. Does that seem ok?

No

 

[moconnell]

For others who might be doing this: maybe you're going for cathedral to preserve headhight like me....for regs basically you must have either for the ridge:
-2 massive glu lams
Or
-a steel.
OR
still use trusses with either:
- raised collar trusses (what i'm doing)
- scissor trusses
...this gives me 25cm extra to make it good head height..(which trusses normally impact if you dont have big walls)

 

[mrrusty]

There is another option, which is what I have done recently with a garden room, and that is to have something in the fit-out of the internals that divides the ridge with a support post/wall into two much shorter ridges. It dramatically reduces the size of the beam needed.

 

[moconnell]

There is another option, which is what I have done recently with a garden room, and that is to have something in the fit-out of the internals that divides the ridge with a support post/wall into two much shorter ridges. It dramatically reduces the size of the beam needed.

Was thinking about one truss half way with a support under and up to the ridge...not sure if span is technically halved? ..prob still hard to get a stuct.eng. to sign off on it. Or did you mean a full beam/pole or interbal wall support from floor to ridge? In which case its breaks the open plan up... looked to me like more complex trusses were also possible but beyond my skills.