Can I build a small home, 20' x 10' on an insulated concrete slab on grade foundation in a cold 3A climate zone?

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Posted by: from Winnipeg
5/19/2014 at 4:15:24 PM

I live in Winnipeg, Manitoba, Canada. The climate zone is 3A and it's very cold here. Temperatures between November and February can drop to -40 C (which is also -40 F). I read this article written by the government of Ontario that talks about the benefits of building a home on a concrete slab on grade foundation.

I have 3 questions.

1) Is this done often in cold climates?

2) What kind of cost could I be looking at for the foundation for a 20' x 10' home?

3) Is this the least expensive method? What other methods can you suggest to keep costs as low as possible? I thought of a crawl space or a raised pile foundation type, but these 2 types are really expensive.

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Date/Time5/20/2014 at 4:35:56 PM

The only benefit of a slab on grade is cost, that's it. It is not done very often in Canada. The problem is the on going cost of trying to heat the space and the uncomfortably cold floor you'll end up with.

You also have to deal with the possible shifting and cracking of the floor in the winter. You just can't insulate the concrete properly or to a high enough R value to solve the heating problems. If the air is -40C then the ground and therefore the concrete touching it is the same temperature.

With a crawl space or even better a full basement, you can insulate the heck out of the walls and the lower your floor is in the ground the warmer it will be. Once you reach about 6' down the earths temperature is pretty much consistent year round.

Do it properly and you'll be happier for it.

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Date/Time5/20/2014 at 7:08:25 PM

Hi Phil,

I would never build a home on a concrete slab. The costs to heat the home would be extremely high. And as the other reply you received noted, there is also a huge potential for cracks and shifting.

Any new build or addition I have ever done has been on a proper foundation. And only one was a crawl space. The clients insisted.

Regarding the cost for your foundation. You will have to talk to some companies where you live to get estimates. Costs vary sometimes to a great degree depending on where you live in this great country of ours.

Hope that helps,

James Fram

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Phil in Winnipeg
Date/Time5/20/2014 at 7:12:14 PM

I'm not sure if you guys read what I linked.. which is a recommended by the goverment of my neighboring province that has similar climates.

Personally you may never, but why is the government recommending this?

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Mark from CMJ Renovations in Oakville
Date/Time5/22/2014 at 7:18:14 AM

I agree with James. It is a low cost effective way to build. It was designed by first nations for rural construction where getting machinery and soil may not be ideal for digging etc.

At the end of the day it isn't recommend by the government but is basically saying it is an option for low cost construction and if you wish to do it this is how it is done.

You may also want to check with your municipality where I live you need a foundation with at least a heated crawl space unless it is considered a sun room.

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Date/Time8/8/2014 at 9:59:21 PM

Building slab on grade can be easily and economically done. I would recommend you look up Dow Chemical and their 'Soils Insulations' literature. Many commercial buildings use this technique which is in most cases a simple matter of installing an extruded polystyrene under the slab and outwards from the foundation to prevent frost from going underneath.

The two most common brands go by the name of Styrofoam ( Dow Chemical ) and there's also another manufacturer that makes a pink product.

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