cantilever joists

[SDUCKEEEY]

 How about moving post and beams in to 18 feet. Leaving space to fill in later with a "false" stone foundation up to a few inches from the joists. The biggest benefit being stiffer floor with less span on joists. There would be 1 foot overhang on each side. 20x32 cabin 1 story

[jraabe]

Not a bad idea. It would make the joists stiffer and the roof loads would not overload the carrying capacity of the span since loads can be offset by the depth of the joist without requiring any engineering (or getting close to the limit of the short span).

It would be trickier for the loft and second story versions of the 20' wide house and would probably require an engineer to do some calcs.

[cancertomnpdx]

I would like very much to have a concrete bathroom, vanity counter, floor, one-step up to sunken tub, etc.  Would the "false" stone foundation idea work to add the extra support you would need to accomodate the weight of the concrete?

[jraabe]

If I correctly understand the idea being discussed here, the false stone foundation is non-structural infill under the wall which has been cantilevered out from the bearing beam. When you have a floor loaded with extra weight such as a large soak tub, a heavy bed of concrete or tile that must not move, then the floor joists are often beefed up by doubling under the bearing point or adding extra joists and put them closer together (12" rather than 16" o/c, for instance). This would be true whether the floor is cantilevered or bears directly on the foundation wall.

For the idea of the bathroom you mention, you may also need to install extra material such as cement mill board over the sub-flooring. Check on this with the builder or tile installer.