I'm building a shop (~950 sq ft) and a cabin (~800 sq ft). They are on Manitoulin island and will be on exposed flat limestone that is randomly segmented. I will be getting the assistance from an engineer, but would like to be somewhat educated and know my options before working with them or the building inspector. I cannot find any particulars in the building code or on the internet for my type of ground. I have concluded that a slab would be the best fit to accomodate any shifting and be the most cost effective but I don't know how I should pour an insulated, above grade slab in respect to maintaining an insulated perimeter. I can only see backfilling over the exterior skirt insulation, which then lends itself to the constant problem of erosion unless the backfil is contained in a crib of some sort.
Also, in order to save on costs building the shop, can I vary the slab thickness to accomodate different loading or do I have to pour one massive slab? I have a 12 tonne truck in one area, footprints for a 2 post hoist in another and the rest is foot traffic. The shop is radiant hydronic heating but the cabin is not as it is only used for emergencies in the winter.
Thanks for any advice!