Saw a detail I liked and wasn’t familiar with in the new FH, p 62. The concrete foundation has a step, with the outer section being 8-10 higher than the inner – kind of like a reversed brick ledge.
The PT wall plate sits on the higher outer section, and a separate double PT plate is used on the lower inner section to support the floor joists.
The reason stated is to lower the floor relative to grade.
Question – what would that do to PT requirements relative to distance from grade? From the sketch, it looks like the bottom of the joist is flush with grade, though separated by ‘crete. That puts the stud bottoms at 7-8″ up from grade.
Also, any perceived difficulty decoupling the floor and wall? Kind of like old balloon framing.
Forrest
Replies
McDesign.
The basic weakness is that concrete will absorb moisture. Since you need to put pressure treated wood between the concrete and the floor you'd also need to put it between the floor and the raised portion of concrete..
In addition everything would need to be put on joist hangers.. since you couldn't simply face nail the joists in place..
Didn't see the magazine, but typical here is to pour the stemwall ~6" above grade, set mudsill as usual, then hang the first floor joists from mudsill using top flange hangers so that the top of joist = top of mudsill. Subfloor goesight over mudsill and walls are built in the usual manner. Holes are drilled where foundation bolts interfere with subfloor.
Of course there's no chance of running plumbing into the exterior walls from the crawl space with this detail, but it gets your floor elevation one step above exterior grade.
Sounds complicated, therefore troublesome.
Build ICF. Hang your floor wherever you want.
Ron
We did one this year for a client who wanted a lower floor elevation for their family room. This was the detail:
Was too small, try this