Concrete pad for garden room

Xcellor

Hi,

I'm looking for some advice on the concrete pad required for a steel tech type garden room. I'm looking at a structure of around 5 x 4 meters. The room will be gym/office space so I'd like to to be as comfortable - what sort of insulating materials should be used I'd like to start getting some prices for the pad. Would the pad be done as normal and insulation ontop or does it need to be within the concrete at the time of pouring?? Any tips/advice appreciated.

Cheers

Lumen

Non-expert opinion…

If you don't need a flat threshold, I'd do insulation over (thick) slab, where the slab bears the load of the walls. The detailing is simpler, it ensures the insulation is kept dry and can be continuous with the (presumably internal) insulation of the garden room. It also has the advantage that you don't need to size the slab perfectly - it can (and should) be wider than the walls, so that the walls are not bearing on the edge of the slab.

If you need a flat threshold, I'd suggest a perimeter block (on edge) wall to bear the garden room walls, then a thin slab on properly prepared base to get everything flat and level, then high density load bearing insulation under the finished floor. Advantage: less concrete as it's only for levelling. Disadvantage: the perimeter wall must exactly match the dimensions of the prefab room, and if you need to replace it later you''ll have to either find one of the same dimensions, or infill the perimeter and go smaller.

Whichever route you go, you want the insulation to be continuous from floor to walls.