Foundation in Minnesota

[Yeager]

Hello all,
I am planning my Pompeii Pizza oven in Minneapolis and have a few questions. It will have pavers on the front side of it (the pavers will have 12" of class 5 with 1" of sand) and was wondering what you would do for the pizza oven - here are a few scenarios I am considering.

1. Dig out 17.5" below surface - 12" of Class 5 and 5.5" of concrete (with mesh re-inforcement)

2. Dig out 19.5" below surface - 12" of class 5, 2 inches of Dow Cornings Foam insulation, 5.5" of concrete (with mesh re-inforcement)

3. Dig out 17.5" below surface - 12" of Class 5 and 5.5" of concrete (with mesh re-inforcement) with four sonotube footings in each corner

any advice?

thanks!
Yeager

[Cubslover]

If Ice Heave is your concern, sonotubes do nothing for you unless you flare them or add feet. It merely gives the ice something to grab.

I talked with a few civil buddies and decided to take a look at nearby concrete at my place before choosing a foundation. My patio is 18x14, 4" thick without ANY reinforcement. I also have a sidewalk that curves around through a garden to the opposite side of the house. NONE of it has shifted or cracked in 7 years so I chose to do a heavily reinforced floating slab.

I dug out 12" below grade, laid 5" of crushed stone and gravel, then poured 8" of concrete over a massive grid of 1/2" rebar and remesh. I laid this grid at 3" above the bottom and another 3" above it. I also took my time curing. As soon as it was dry to the touch, I began misting it with water. I then covered it with plastic and kept it wet for a week. Proper curing is key.

I feel very confident that it will not crack through our winter/spring cycle. We will hit -15 to -20 during the winter at times, but I know your winters are probably a little more severe.

[gastagg]

You will find extensive debates on this forum about whether or not to pour foundations below frost level or settle for a slab. Many guys will say that you must pour foundations regardless. Some will argue that if you're not planning a large kitchen installation that spreads out over a large area and are not attaching the oven to another structure, then a stand-alone oven will do fine with properly prepared ground/gravel/rebar setup. I live in Minneapolis and chose the slab option. I dug down 12", placed 6" of class V compacting every 2" and poured a heavily-reinforced (mesh and rebar) 6" slab. Now, I haven't gone through my first winter yet, and I'm not even done with my oven, but I'm sure that if this sucker moves, it will move as a unit. If it moves and doesn't move back to level, then I will regret my choice. But I've got a large patio with a similar prep and I haven't noticed any heaving that doesn't come back to it's original place.

[RandyJ]

I also live in Minneapolis area and went the slab route . I went 12" thick all the way around the edge and 6" deep for the rest, and lots of rebar. I also have not done my first winter but am not worried about it. Good luck with your build. I am almost done with mine.

Randy