We are rebuilding our garage as part of planned extension works. The existing, single garage is attached to the side of the house. Under the new plans it will be knocked-down and moved forward by approx. 70cm. The extension is a single-story ‘wrap around’ with a kitchen extension at the back, a utility room at the back of the garage adjoining the kitchen extension, then the new garage.
The architect has suggested building the garage using cavity-walls, to allow easy and planning-free conversion if we ever want to make it an extra room. We are confident we never will (need the garage) and access to the main house will always be tricky (via the utility) so not ideal as an extra bedroom.
My question is, is the cost difference substantial to build as single brick or cavity wall? It really only affects two external walls of the garage (one of which has the roller door anyway), as the other two border the existing house and the new utility. The garage roof will be a continuation of the side pitch of the new extension. I hope this makes sense.
Obviously we can ask builders to quote for both but we are just at the stage of submitting plans and not yet ready to get detailed quotes. I just wondered if anyone had experience of rebuilding a garage and the costs/other disadvantages of using cavity walls.