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My home has a walkout basement that the past owner had attached a 10×16 sunroof. Since I was considering adding a second level above the sunroof I curiously dug down to check the footing. To my surprise there was no footing. They poured a slab and laid five courses of block on top of the slab. Three of the five courses of block are buried with the exception of the walkout side (south) where the slab is exposed at grade. Surprisingly for northern Minnesota, so far only the west wall has moved away from the main house approximately 3/8 of an inch.
What should I do? Is it possible to excavate under the slab and build a proper foundation? Does anyone have any other creative (and less expensive)ideas on fixing the problem?
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Hi Denny,
Need to know the thickness of the concrete slab and the type of soil its founded on.
It reads like it could be a floating slab that was built onto after the fact.
It's doubtful that you can build another level over this slab.
If you're seriously looking at building a second level, given that you probably won't be able to add to it and will have to put in proper footings below frost, maybe you should consider changing the design.
You could dig around the outside of the slab (so that you can save it) pour the footings and increase the size ever so slightly. Frame in the new sunroom, using as much of the existing materials and windows.
Make sure that you design this new room for the addition of the second level and your off to the races.
Gabe
*Like Gabe said, a foundation wall could be build right outside the existing slab and the whole thing made 16" larger.Underpining can be done. The slab can be excivated in small areas, jacks put in place, the rest excivated, concrete poured, block pointed into place to support the slab, and finally the jacks removed. Slabs crack, sounds like tricky work.
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In the area I dug up the slab was 6" on the edge. The soil is sandy loam and drains very well near the slab.
At this point I've given up on adding a second level. I just want to secure the level that is there.
Thanks for your response :)
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My home has a walkout basement that the past owner had attached a 10x16 sunroof. Since I was considering adding a second level above the sunroof I curiously dug down to check the footing. To my surprise there was no footing. They poured a slab and laid five courses of block on top of the slab. Three of the five courses of block are buried with the exception of the walkout side (south) where the slab is exposed at grade. Surprisingly for northern Minnesota, so far only the west wall has moved away from the main house approximately 3/8 of an inch.
What should I do? Is it possible to excavate under the slab and build a proper foundation? Does anyone have any other creative (and less expensive)ideas on fixing the problem?
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Hi Denny,
Your slab may not need to have any further work done to it.
The small amount of settling that you described is really nothing to worry about.
If your soil is sandy and drains well, the movement will always be minimal.
Gabe