Flat roof timber span

th3joker · 3 Jul 2015

I'm connecting the Garage onto the house and need to redo the roof.

The span length is 4930mm on top or 4780mm off hangers what size timbers would I need to buy.

Planning to use ply and rubber on top, in Cornwall so we basically get snow once every ten years and it's never deep.

Thanks in advance for any help or suggestions

freddiemercurystwin · 3 Jul 2015

About 50x220 @400cts, they may possibly be a little undersized. Any smaller may be risking some deflection. But that's taken from the standard Trada span tables.

th3joker · 3 Jul 2015

freddymercurystwin said:
About 50x220 @400cts, they may possibly be a little undersized. Any smaller may be risking some deflection. But that's taken from the standard Trada span tables.

thank you very much

th3joker · 3 Jul 2015

Could I go thicker, say a 75 and reduce the height?

freddiemercurystwin · 3 Jul 2015

75x195's would work but will probably cost more.

freddiemercurystwin · 3 Jul 2015

Or post in Building, may get one of the engineer types to do some number crunching, I'm just going by the standard tables tbh.

th3joker · 3 Jul 2015

Appreciate the help, I will ask in building

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Flat roof timber span

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