What is a boundary?

[kgnoble]

If your building is more than 1m from the boundary you only need the fire resistance from the inside. The internal plasterboard will take care of this.
Just to clarify the last sentence of my previous post you have no problem with surface spread of flame.

Thank you - everyone - for all your replies and advice. I will keep you posted as to how I get on.
Keith

 

[John D v2.0]

if the building is 45m2 then it will still be subject to building control, so the 30m2/1m exemption will not apply. Therefore you may still have to limit the unprotected areas based on the actual distance from the boundary - but a lot depends on the actual definition of unprotected areas and whether your current building meets the definition. Others may know more.

 

[jeds]

30m² exemption wouldn't apply, requiring a full application. Separation distances would still apply.