Foundation and a cold Canadian winter

[dbhansen]

Originally Posted by John.Halder

Did you use the Forno Bravo plans?

Glad my pictures were useful, John! Yes, I did use the Forno Bravo plans, and borrowed ideas from lots of other members' pictures. Digging the foundation was a LOT of digging, but it went surprisingly quick given our thick clay soil. This is the foundation's first winter, so I'll see how she held up once the snow melts. If you have to dig by hand, I think the floating slab might be the best way to go.

Daren

[tdibratt]

I built mine in Canadian Winterland as well. I used the floating slab approach which I learned when I built a garage a few years back up in the Parry Sound area. The concrete slab is built with integrated footings about 12-16 inces wide and 12 inches deep. When I did the garage we did not even require insulation. The concept is to dig down your perimeter trench 12-16 wide and 12 inches deep so that the inside perimter of the trench is tapered. For example if I was looking at a cross section of the trench on the right side, the outside cut would be straight up and down. The inside cut would taper from say 16" wide at the top to 12 inches wide at the bottom. So the line would go from left to righ as you go from top to bottom. If you picture this effect all the way around you essentially create an area where when poured with conrete locks the slab into place so it cannot shift left to right. You then put in rebar into the trenches. 2 rows. Use vertical peices of rebar to hold the two rows in place and have them extend up high enough so that the actuall slab rebar grid ties into the vertical pieces. You create a rebar structure with the rebar in the footings and the slab tied together. Pour your concrete. Now if monther nature wants to play with your slab ans try to heave it a bit, the whole slab will raise and lower with frost but not impact the structure on the slab. That is the concept. Now what I did for my own is I went down far enough in the perimter to give me about 3-4inches od gravel, followed by 2 inches of blue syrofoam insulation (ridgid) and then the concrete went in over this. This has been my first winter and although I have not gone out to inspect closely, I can see my oven from my window and nothing appears to have moved. Again even if it did, the whole oven would move with the slab. I am no engineer so I cannot comment on this process being bullit proof but it worked for me and makes sense.