Foundation and a cold Canadian winter Getting Started Discuss Foundation and a cold Canadian winter in the Pizza Oven Design and Installation forums; Hi there, I'm new to this site and am looking for information on how people have done their foundations to ...

[ekah]

Hi there, I'm new to this site and am looking for information on how people have done their foundations to deal with frost problems. Thanks

[dmun]

There are two approaches. You can dig down under the frost line, pour heavy footings on bare soil, and build up from there. This is what you need to do if your oven is part of a building which needs to conform to building code for masonry fireplaces.

If your oven is freestanding, you can pour a four inch slab on a well drained crushed rock bed. The gravel drains away standing water, and prevents frost heave.

Here's an interesting article from Canada, detailing a method of building shallow insulated footings. You need special high-compression insulation board to withstand the weight of the structure for this.

ESB: Frost-Protected Shallow Foundations

Good luck with your project.

[staestc]

Welcome to the forum Ekah!
Travis n'Texas

[dbhansen]

I live in northern Wisconsin and did a deep foundation. Not necessarily the best way to go, but it works. Pics are available via the 2 links below.

[sarah h]

Hi Ekah, and welcome!

I'm in Ottawa too and built last fall on just a 6 inch slab on top of a gravel bed.
If I had done more research first, I might have gone with something more substantial but my oven survived last winter without any problems. That said, however, please don't take this as a recommendation - I don't feel qualified enough to provide one - just saying what I did ...

Are you right in the city or in the outskirts?

Best of luck with whatever you decide to do - I'll look forward to watch your progress here on the forum.

Sarah

[Versachi]

Welcome Ekah. Another Canadian yippee! I'm up in Thunder Bay with winters much worse than most here on the forum. I dug down 16 inches and filled it with gravel which I compacted and have a six inch slab on it. No movement in the slab last year. Keep in mind that the ground where my slab is is very sandy so there is little water in soil which would cause it to move.

Cheers, Versachi

[ekah]

Thanks to everyone for their comments. Given that winter is just starting to be a reality, I won't undertake the construction until next spring. Until then, lots of planning to be done.

Thanks again.

[Ed_]

Originally Posted by dmun

Here's an interesting article from Canada, detailing a method of building shallow insulated footings. You need special high-compression insulation board to withstand the weight of the structure for this.

The article is definitely worth a read. Although they do emphasize the need for sufficient compressive strength in the insulation beneath the slab, I don't think that's too big a concern for an oven.

A quick bit of math shows that if you have a 5' by 6' slab, the slab plus the structure on top of it would have to weigh over 21 tons to get up to 10 psi on the insulation. You should definitely check specifications, but I think most extruded polystyrene insulation is rated at 10-15 psi. And while your oven will be pretty heavy, you won't come close to 20 tons, so you have a good margin of safety.

For comparison, ten cubic yards of concrete would weigh about 20 tons.

[John.Halder]

Originally Posted by dbhansen

I live in northern Wisconsin and did a deep foundation. Not necessarily the best way to go, but it works. Pics are available via the 2 links below.

Daren,

Thanks so much for such a comprehensive set of photo's. Wow. It's almost an instruction manual by itself.

I've been wondering for a while on the type of foundation - but I think if I followed your deep one I'd need to hire a back hoe - judging by the photo's I've got about 20 more years on me than you do, and I'm not sure I'm up to that amount of digging! Our climate will be about the same, though - I'm close to Iowa City.

Did you use the Forno Bravo plans?

Again - thanks for the "help."

John

[rroughtrade]

Here in Atlantic Canada, we have many of the same problems that you have in Thunder Bay, though our winters have a much shorter thaw and refreeze cycle meaning that we are a little more prone to frost heaves. Instead of building a poured slab foundation, we are thinking of going with a poured footing which will both keep the costs down and be resistant to frost heaves. At least in theory, this should protect us from both frost heaves and water inflitration if we get heavy rains.