Frost protected shallow foundation retrofit?
I have a ranch with a full basement and attached single car garage in Southern Maine I am about to gut and remodel. The plans dictate that the garage be changed over to a master bedroom/ bathroom. We will be decking over the existing slab which could be removed if necessary. There are a few cracks in the 8″ x 4′ frost wall and we have determined that there is no footer. The obvious and easy solution was to dig it up and replace it with proper footers and insulation. The question is, can we leave the frost walls and insulate to create a frost protected shallow foundation and raise the frost line ( http://oikos.com/esb/43/foundations.html). Would I be taking chances with more heaving and cracking or should this stop further damage and allow me to build on top of the existing frost walls? Any thoughts?
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If your foundation has been heaving and cracking, I would be very wary of your proposed solution. In any case, I think you need to hire an engineer who can make a site visit rather than relying on advice provided over the internet.
I think the current issue of the Journal of Light Construction has an article on this exact topic.