Garden Room - {Pub Shed}

[Baxter111]

Hello,

I’m currently build a garden room / pub shed for use in the weekend and evenings.

I’ve built the base and insulated it with kingspan slabs and I’m going to build the sides/roof this weekend.

The roof, I’m using OSB3 18mm boards and intend to felt the roof either with torch on felt or the classic nail job, my question, do I need a membrane or will it be ok to felt straight onto the OSB3?

Also the sides of the shed will be 15mm OSB3 and I’m going with a shiplap finish, does this need a membrane behind it and some thin joists for the shiplap to sit on for it to be breathable?

I’m also going to insulate the walls too.

 

[Alastairreid]

9mm osb will do for the walls with builders paper 25x50mm battens for air gap then shiplap.
Roof pitched or flat? Consider epdm which is a good DIY product.