what the timber size should be to span a 4.5 metre wide roof?  Its a mono 
pitch roof which spans 4.5 metres from eaves to ridge.  Its 8 metres long. 
Redland Cambrian slates will go on it.
Cheers

Stuart

"Stuart"  wrote in message 
news:d43dmb$ba5$1@newsg2.svr.pol.co.uk...

> what the timber size should be to span a 4.5 metre wide roof?  Its a mono 
> pitch roof which spans 4.5 metres from eaves to ridge.  Its 8 metres long. 
> Redland Cambrian slates will go on it.
> Cheers
>
> Stuart

There is a rule of thumb method but I'm not going to tell you how to do it 
as it should not be used by amateurs.  Building Control will require you to 
demonstrate that the joists are adequately sized for dead and live loads.
This is a very simple calculation for an engineer which should take him all 
of 10 minutes. He will calculate the joist sizes and check that deflection 
is within acceptable limits. There is also the need to ensure that the 
structure is adequately tied and connections are suitable. My advice - get a 
professional engineer involved. Alternatively, you could commission a truss 
roof manufacturer to design and construct the trusses for you. This is a 
cost effective way of doing things.

Thanks for the advise Bob
Stuart
"Bob Hill"  wrote in message 
news:p1d9e.12443$DU6.4480@newsfe1-gui.ntli.net...

> "Stuart"  wrote in message 
> news:d43dmb$ba5$1@newsg2.svr.pol.co.uk...
>> what the timber size should be to span a 4.5 metre wide roof?  Its a mono 
>> pitch roof which spans 4.5 metres from eaves to ridge.  Its 8 metres 
>> long. Redland Cambrian slates will go on it.
>> Cheers
>>
>> Stuart
> There is a rule of thumb method but I'm not going to tell you how to do it 
> as it should not be used by amateurs.  Building Control will require you 
> to demonstrate that the joists are adequately sized for dead and live 
> loads.
> This is a very simple calculation for an engineer which should take him 
> all of 10 minutes. He will calculate the joist sizes and check that 
> deflection is within acceptable limits. There is also the need to ensure 
> that the structure is adequately tied and connections are suitable. My 
> advice - get a professional engineer involved. Alternatively, you could 
> commission a truss roof manufacturer to design and construct the trusses 
> for you. This is a cost effective way of doing things.
>