Shed roof

[Stringman_uk]

I have a bit of a situation.
I have build a summer house (4.5mw x 2.5md) and its all treated T&G with a rubber membrane sloping ( front to back) roof.
We have decided to add on a cooking shed ( 6ft x 4ft) on the side ( so 1.8m front to back 1.2m left to right)
We have clad it in the same T&G so that it lends in. which it does pretty well.
Obviously, as the height is lower than the actual summerhouse you can see the roof ( just bitumen felt) so we got to wondering if we would cover the bitumen with the T&G as it would blend in with both structures.
Would it cause any potential rot problems as it is treated wood and there is is bitumen below ( and we can add TYvek as well)

Any Thoughts?

Thanks in adavance

 

[DAZB]

Your problem would be the fixing method as you would need a structure to fix the t & g to and nailing or screwing through the roof covering may give you problems. It is perfectly possible but just bear in mind you have to keep the waterproofing intact and that t & g laid on a pitch roof exposed to the weather will not last more than 4 or 5 years given current weather trends.

 

[Stringman_uk]

Thanks for the reply.
The roof at the moment is 18mm osb covered in felt. I would either nail it direct to the felt roof or put battens on.
Good to know about the lifespan. I wonder if there are clear water protection treatments?