Single storey vaulted pitched roof

[PULLMYFINGER]

Hi i was hoping someone could assist me, we are looking to extend out home and i'm trying to put together some building regs drawings. The building is single storey mainly brick with curtain wall style glazing to the front which goes follows roof slope. Now with the glazing going so high i dont want a flat ceiling so there wont be any ceiling joists and new ceiling will needs to follow the rafter line underside.

1) Can these rafters be timber if so what size
2) what size timber purlins need to run between and at what centres
3) How are the rafters restrained to avoid pushing walls out as there isn't any cross timbers tying the rafters together like a normal truss.

Thanks in advance for any help.

 

[garyo]

You need your glass end gable to be structural. That's to say it'd probably need a steel frame integrated within it (or around it) to hold your ridge beam up. The other end of your ridge would be embedded in the house wall, and then your walls won't spread because there are no forces to do so.

What's the design for the glass gable wall?

 

[PULLMYFINGER]

Thanks for your assistance garyo.....there is no official manufacturers design as yet. its just detailed how i would like it to look.

So does the ridge beam running from main house wall to new glazed wall need to be steel or would timber surfice?

 

[tony1851]

As above, you would need a ridge beam rather than ridge board.
Also, your rafters would need to be stiff (ie deep) enough to prevent excessive deflection which would
tend to push the walls out at the top.

 

[PULLMYFINGER]

Dont suppose you know what size the rafters would need to be? also assuming rafters where deep i could omit any need for purlins?

 

[^woody^]

Your walls aren't high enough. Rafters will be at least 175 deep

 

[PULLMYFINGER]

oh no....Why are the walls not high enough? I thought they could be under 2.1m as there is no windows or doors to the side elevations just brick

 

[freddiemercurystwin]

You'll have a pretty low headroom alongside the walls. As mentioned a steel solution is required to support the ridge beam, probably a 152x152 steel or 2 x 200x50 timbers. As mentioned whilst at one end it can sit in the wall the other end will either need to sit on a column that goes down to the foundation or a steel portal that sits up in the rafter zone and is supported on each flank wall or maybe a horizontal steel beam at the top of the doors supported on each of the flank walls with a small column supporting the end of the ridge beam. No need for purlins.

You'll need a structural engineer, the window/door manufacturers will be no use.