I purchased your Little House Plans a few years back and built a 12x18 cabin, in Maine, with loft. It is completely finished, heated, and used for an office. For its foundation, I placed 9 pre-cast re-enforced concrete pads that measure 16" in diameter and 6 " thick on a compacted surface of 3/4 gravel - 3 rows with three pads each. I then placed 6x6 PT beams on the pads. This is the 4th winter and I've had no problems
I am now going to build a new 14x18 building, also n Maine, with the plans I have, using the concrete pads but with two rows of three pads with two 4x 10 beams as the foundation. However, I saw where you have some new information on foundations. Can you pass this information along?
Thank you,
jmm1890
Here's a bit more detail on pier and beam foundations that may be helpful.
http://countryplans.com/foundation/index.html
It sounds like you probably have those gravel footings pretty well worked out. That new building would not add much additional weight and the same system could work. The deeper footings in the diagrams do help anchor the building better if you have heavy wind or earthquake loads. Otherwise your modified system seems fine as long as you don't have expansive clay under the footings.