Following on from my previous question: Can I have two storeys in a 16 foot space?
It looks like the "best" use of that crawlspace area would be to build a new floor inside the 16-foot crawlspace/basement - a large livable/usable finished day-basement room with a somewhat unfinished storage area underneath. But I'm wary of the cost involved in inserting a new floor into the existing house structure.
Another option for adding more square-footage to the house that I'm looking at is extending the top floor of the house by having an elevated extension (on legs/stilts). It would not surprise me if it did end-up costing the same because while more "new" work is needed (i.e. adding new exterior walls) I believe it would be less hassle - "greenfield vs brownfield".
Here's what I'm proposing, via MSPaint:
So the top-floor would be extended northwards by about 2-3m, greatly increasing the floor-area of the two bedrooms, as well as adding a walk-in closet for Bedroom 3 and a Jack & Jill shower-room (or two separate shower-rooms). I think adding a deck/balcony that stretches the length of the house would be nice (as the north face of the house faces a wooded area) - it could be covered too, and then the bedrooms would both have their own french-door access to the deck/balcony.
Of course, note the problem is that it's essentially 30-feet from the west-end down to the ground below. I'm assuming a builder can source structural timbers long enough for that.
But an advantage is that the entire foundations don't need to be massively-extended, a set of pile-driven single foundations would be all that's necessary (would you even need a pile-driver?).
Is my proposal feasible? And if so, how much is this likely to cost in comparison to installing a floor into, and finishing, the basement?