ajk1
Dad & I overlap, we can't take credit for the cumulative total of years. The Ontario & National building codes do not require 1.2m frost cover. That's a prescriptive number for soil used for Part 9 in place of engineering judgement and design (and it actually says 1.2m "unless local experience says it should be otherwise"). An engineer should be able to distinguish between when the prescriptive number is convenient, economical, or necessary; when a material other than soil is appropriate (insulation?); and when neither is necessary or appropriate. If one can't, that's fine, they can defer to someone who can. There are a multitude of configurations and circumstances, and appropriate design details for them. Clay, sand, gravel, peat, rock; they all require different considerations. That doesn't mean one has to default to the non-engineered approach. It might seem impossible but I have a 1500 sq.ft. unheated barn attached to a 700 sq.ft. heated workshop on a continuous reinforced concrete slab on grade. The barn sits on a 2' high 2-wythe kneewall of block & brick bearing a heavy timber structure, and the workshop is of typical stick framing sitting directly on the slab with a 2' high brick skirt to deflect splash from the roof. There's plumbing in the workshop. There isn't a crack in the masonry & nothing but shrinkage cracks in the slab, it's more than 20 years old (I dismantled & relocated the 175 yr. old barn), and it's founded on clay, but it's properly designed, drained, and insulated. I've designed and built countless heated & unheated structures on reinforced slabs including a 6000 sq ft church with 54' span scissor trusses and 100% masonry exterior cladding (built 2010, no drywall cracks in 2015), a 6000 sq.ft. unheated pre-engineered steel building for Ontario Hydro (25 years ago) and within the last 2 months 3 pre-engineered steel buildings >7500 sq.ft. both heated and unheated. I've also seen plenty of designs from other engineers for similar buildings (contractors love to shop), with very little deviation from what I would recommend. Just because one hasn't managed to do it oneself, it doesn't mean it can't be done.