how much to build a single attached, flat roof garage? with the strength for it to be built on top of for a future house extension, what would be recommended single or double lined??? or what the term is for it, not sure of that part.
Well, between �5-8k for the straightforward garage.
If you are thinking of building over it at a later stage you really need to have it drawn up properly by someone who can design it with either bricks piers at the corners for steel lintels later over, or you build with a conventional double skinned wall. Its the inner skin of a conventional brick/block house that supports the roofing trusses - not the outer brick skin.