Can you jack up a cottage and build a slab on grade underneath it?
I have a cottage in Quebec which used to be resting on the ground. In the 1950s they dug under neath and poured concrete and used cement blocks to make a three quarter basement. It is wet in the spring and damp throughout the summer making the bungalow humid in all seasons. THis mostly due to the house being directly next to a hill.
I've looked at your radiant air heating solution and was wondering if it would be possible to raise the house 2-3 feet and put it on gravel and an insulated slab while turning the basement into a thermal battery by filling it with sand and running piples through it. If so, can you recommend any companies who would be up to the task?
Yes, you can for sure jack up a cottage and build a slab underneath and drop it back down. 2-3 feet won’t do it though, you’ll need to get it high enough to work under there. Generally that is something you’d hire a specialized contractor to do, you weren’t planning to do this yourself I hope? Lifting a building high enough to build underneath is a much more risky undertaking that jacking up a cottage a bit to level it.
Your cottage would need to lifted high enough that you can at least get a Bobcat under there to level it, add clean crushed stone and compact it, then install all the foam forms and insulation. The company that provides engineered raft slab on grade kits with air heated floors is Legalett, the serve most of North America and certainly Quebec, they designed our solar air heated floor for our last LEED Platinum demo house in Wakefield, QC.
Thanks for your response and the link to get a quote. Yes, I understood that the house has to be much higher during the construction phase. I've seen many houses propped up like this in Constance Bay when being repaired after flooding. Perhaps I didn't phrase the question well. The objective, after the rebuild, is that the house will rest 2-3 feet higher than it was prior to putting slab on grade in place. What you didn't answer was whether it is economically viable to convert the old basement into a thermal battery. Perhaps this is not your area of expertise so I shall seek the answer elsewhere. Thanks again.
Just curious what was the outcome ? I have a very similar cottage like yours and was debating about putting a slab underneath it , also in Quebec ( Buckingham ) area .
I had a company (local to Gatineau) come round just to give me a quote to raise/move the house to actually do a 10k slab. They charged $350 just to visit the property and then their quote was $40k just to raise and move the house. It made raising the house more expensive than the entire project put together. What annoyed me most was the fact that I referred a colleague to them and they didn't charge him to visit his propoerty or for a quote.
I decided that I could get huge amount of landscaping done for a quarter of the price to resolve the real problem which was the drainage around the house. So - I would have a good look at your property and see if you can ensure that the water is moving away from your house instead of running into it.
As for creating a thermal battery - Mike has a point that if you make a thermal battery under your house you need to insulated it on all sides. That's a given however the real issue is any kind of maintenance would require digging up your basement and the slab.
Instead, if you have the land, create a hole and insulate it on all sides and make that your thermal battery. You can heat it with passive solar and use it for hot water and/or radiant heat or a heat pump. Then you can always maintain it as it is away from you house.
If you raise your cottage and put an insulated slab underneath and drop it down on top, the concrete of that slab becomes the thermal battery. For something to act as thermal mass and store heat, it needs to be separated thermally from the ground. Unless you plan to insulate underneath the sand then it wouldn't benefit you.