foundation for cold weather

[jgv109]

I just downloaded the plans and would like to build a raised version of the pompeii oven. I live in an area where freezing and heaving of structures is normally an issue to consider - has anyone in a cold area dug the traditional 3 ft foundation to support the walls when building one of these ovens ? Thanks!

[azatty]

Lots of people on the board have ovens in New England. There are a variety of solutions. Do a search on "frost heave" and you'll pull up a ton of threads describing the various considerations and solutions.

[Aegis]

Originally Posted by jgv109

I just downloaded the plans and would like to build a raised version of the pompeii oven. I live in an area where freezing and heaving of structures is normally an issue to consider - has anyone in a cold area dug the traditional 3 ft foundation to support the walls when building one of these ovens ? Thanks!

I live in Ct. and although this winter hasn't been too bad last winter was a bute! I had my slab and stand constructed before last winter and it has survived well both times so far. I have clay/ledge soil,the worst for frost heave damage so if you have anything better no worries! (And anything is better than clay!) I dug down about a foot and dumped in 3/4" stone for drainage and I also dig 9 holes for sono tube and went with the "pillar" foundation. Here are some pics, I went down 42" for the tubes or I stopped at ledge. At the bottom of the tubes I put in some 3/4 stone for drainage until I hit the 42" mark. Drainage, drainage, drainage is your best friend! From the under the base I also had drainage pipe running down the back. This is connected to the drainage pipe I put in for the retaining walls and patio area. Good Luck and enjoy your build! btw the pompeii oven works GREAT!
John

[vtsteve]

I have a plain 5.5" reinforced slab in central Vermont, resting on three feet of compacted stone (I kept hitting debris from 130 years of previous renovation - including two ash layers - so I kept digging). Now my patio heaves up and down around the oven .

[Dino69]

I will be doing a pier foundation as Aegis has done. Also planning on belling out the bottoms. My frost dept is only twentyfour inches so I will be going thirty, or a bit more, and adding drainage rock. I need to have a building permit here and "the man" said it would be fine.

They actually plan on coming out to inspect my footings. Then he said he would be back when it is all completed. Seems to me there might be a few things in between those two stages of building.

David

[Mingy]

There seems to be a lot of confusion about the impact of frost heave on various structures. People put a lot of effort into over engineering these things for no particular reason. You have to worry a lot about frost heave when you have to connect to other structures such as a deck connecting to a house.

I have a 24' x 40' garage on a slab and this summer will be constructing a 40' x 100' workshop on a slab. Thats just a floating slab. My oven is on a floating slab and there is no reason to be concerned than anything bad will happen as a result: it'll go up a bit and it'll settle down a but with the thaw/frost cycle. Nobody puts foundations or frostwalls or sonotubes on sidewalks do they?

So, remove the topsoil, make sure there is a well drained compacted gravel base and get going.

Have a look. This is from Canada. We know cold. http://www.cmhc-schl.gc.ca/publicati...2000-127E.html The styrofoam is to reduce heat loss during the heating season, not to prevent frost heave.

[Neil2]

Mingy has it right.

A well reinforced floating slab is the way to go on frost susceptible soils. If it is tied in any way to the patio or other structures, consider a pile type foundation.

[jgv109]

Thanks to everyone for sharing their approaches! I'm new to the forum but I have to say this seems like a great community of folks.

...at the moment my husband is concerned that a slab without a suitable foundation will not heave in a uniform way and the oven sitting on a slab without a foundation may be damaged...his current plan is to dig a trench 8-10" wide and 3 ' deep around the perimeter of the slab and fill it with concrete to the grade

I'll definitely encourage him to read through this forum before we start the dig...the "big dig" if we follow his plan

Thanks again! Best, Jeanna

[Mingy]

I've seen lots of unusual solutions suggested here to the cold weather problem ranging from slabs a few feet thick to sonotubes down a few feet with a slab on top to a foundation below the frost line. These are not only expensive, they have their own issues like cost, or the possibility things could be worse as a result of the proposed solution. You can think of frost heave as expansion and contraction: The oven is so small, no matter what you do, the ground will freeze below it. Sonotubes will add weight (a downward force) putting huge strains on the slab.

If you confine frozen earth (by boxing with a foundation) it will freeze and force up and out. This will probably be enough to crack any wall or slab. This doesn't happen with a house because a house if big (and heated).

A floating slab will rise up and settle down. We aren't talking a foot or two, more along the lines of an inch or so. If properly reinforced as per the instructions, it'll rise up a bit then settle down a bit. There will not be undue stress on the structure as with other solutions.

I should stress that any construction needs a suitable soil, regardless


* edit * I want to clarify my comments about a foundation and slab and stresses. When they build a house, they take care to not connect the floor slab to the foundation when the floor slab is ground level, like in a garage. This way, if there is soil movement upwards, the slab kind of floats and then settles back. So, if you build a foundation, below the frost line and a suspended slab (the bottom of the oven) and the floor (storage area) floats, you should be ok. Its a huge waste of effort and cost, but it should work. If you tie a frost wall or tubes into a ground level slab, thats when you've got the stresses I've mentioned.

By the way, I have heavy equipment, including a backhoe, so I don't have to dig by hand. Nonetheless, I don't see the point.


If you don't believe my link from the Canadian government, research slab on grade construction in cold areas. As I have said, it is quite common in cold climates for out buildings, etc.. Also, as I noted, when do see foundations around driveways or sidewalks?

[Aegis]

Originally Posted by Mingy

I've seen lots of unusual solutions suggested here to the cold weather problem ranging from slabs a few feet thick to sonotubes down a few feet with a slab on top to a foundation below the frost line. These are not only expensive, they have their own issues like cost, or the possibility things could be worse as a result of the proposed solution. You can think of frost heave as expansion and contraction: The oven is so small, no matter what you do, the ground will freeze below it. Sonotubes will add weight (a downward force) putting huge strains on the slab.


By the way, I have heavy equipment, including a backhoe, so I don't have to dig by hand. Nonetheless, I don't see the point.


If you don't believe my link from the Canadian government, research slab on grade construction in cold areas. As I have said, it is quite common in cold climates for out buildings, etc.. Also, as I noted, when do see foundations around driveways or sidewalks?

Wish this info was available when I asked these questions two years ago All I got was to ask local builders and inspectors what was needed in my area. I will keep my fingers crossed and hope for the best. That is all I can do at this point....