When I first got into construction a couple decades ago, I was working for a roofing and siding contractor doing a new development. Houses were going up so fast

When I first got into construction a couple decades ago, I was working for a roofing and siding contractor doing a new development. Houses were going up so fast that as soon as we finished one house, the next was one ready for us. My recollection is probably about 12 to 15 weeks start to finish, which is approximately in line with your 100 day number. Although, if you already have the land, you can potentially buy a mobile home, have it delivered and setup, utilities hooked up, and move in within a week, for a lesser overall price. There are a lot of tradeoffs, though.