I’ve been receiving rather unpalatable quotes from helical piling/ground screw companies for my small home. I do love the minimal environmental impact they have, but the financial impact was looking significant: ~$5000 – $7000 for the pilings, plus whatever the wood frame deck would cost. A foundation is important and if that was the only way, I’d go for it, however reluctantly.
Yesterday, I met with an engineer- more about that in another post, but he offered up a much closer to ideal solution: the Frost Protected Shallow Foundation (FPSF). Technical links, below.
Heat flux is core to the concept of a FPSF. A heated dwelling will transfer a certain amount of heat to the surrounding soil, which will reduce the frost depth significantly. The depth required of a FPSF is dependent upon the temperatures in a region- and there are maps that detail this. In my part of Pennsylvania, the depth required for this type of footing is only 12″! That should minimize impact to many larger tree roots and lead to lower excavation costs.