We started a 14 wide cabin 2 years ago slowwing still going at it almost all done. We've hit more finiacal obsticals them we thought, but so it is with 2 kids. We would like to add on to make a it bigger. We built our cabin 28' long and the wife saw the layout on the volks plan and asked can we do that on the side of ours to expand it. Heres the question can it be done on piers i was thinking(yes i now i shouldn't) 2 main outside and a center beam we would just use truses for the roof so i wouldn't need a bearing wall>
I don't see any reason you couldn't - just follow good building practices.