Garage conversion structural engineering

Garage floors are usually a thin, unheated concrete slab that falls towards the door for drainage and sits directly on the ground with little or no insulation or damp protection. To become a habitable room the floor normally has to be rebuilt or built up, either as an insulated slab or a suspended floor, and the level raised to meet the house. We advise on which floor build-up suits the ground and the levels, and design any suspended floor structure and its bearings where the slab cannot simply be topped.

Because the garage floor was never a habitable floor, we also look at what is under it. Where the existing slab is breaking up, was poorly laid, or the ground is soft, a new floor may need to span rather than bear directly, so we size it for the imposed loads of the new room. Getting the floor right is often what turns a cold, damp garage into a room that performs like the rest of the house.

Garage walls and foundations are frequently lighter than the main house because they only had to carry a garage. Where the conversion adds load, for instance by building the infill wall or raising the roof, we check the existing walls and footings and design any strengthening. On a detached garage becoming a habitable building we treat it more like a small new structure, checking the whole load path from roof to foundation rather than assuming the garage build was adequate.

The calculations are prepared to the Eurocodes, the relevant UK National Annex and Approved Document A, and cover the door infill, the floor, the lintel and any foundation work as one package. We work from your architect's or designer's plans and coordinate the structure with the design, so you get a set your builder and Building Control can work from without a run of queries.