Has anyone done one? Tips, techniques, cost factor is big. We'd probably like to excavate underneath total unbalanced fill ~3', frost line is 2'. No concrete so approved techniques for bracing the bottom edge would be much appreciated. This will be inspected. Thanks!
Please define PWF thanks.
Pressure treated wood foundation= PWF. I don't trust them. I have seen to much pressure treated material rot away to ever want to use one.
It's not your everyday treated wood. My nearly 35 year old log home sits on one. So far, so good !
I agree, but I probably just got outvoted, I'm exploring options in the wake of a fire. The spec there is UC4B treated, foundation grade. One of the guys has done repair on one and expects to do more. The season of easy concrete and block work is closing but we'll get it.
Don, you're always a source of some good learning. I'm semi-curious about a PWF for my cabin build so I went and looked it up.
In reading the Southern Pine Council's manual, it appears that a crawlspace foundation is when the backfill imbalance is less than 24".
Greater than that and you are in the basement foundation design realm, which requires the bottom of the foundation walls be braced by a slab or a wood floor. Wood floors are in Appendix II, page 44.
http://www.hillspg.com/pdfs/Perm%20Wood%20Foundation.pdf
Thanks CT, I missed that. For concrete or masonry foundations the break line is at 4' of unbalanced fill. I do like a slab under any house for bracing, moisture, rodents and ease on the subs. We won't have the bucks here though, it'll be plastic. On the garage job a groundhog tunneled under the foundation and came up in the crawlspace, then he stripped asbestos off the heating pipes and lined his burrow with it. That crawl is definitely getting a slab.
Don't tell me you took away that poor chucks insulation? I think you would be in violation of removing AND improper installation in that case. :D
Removal takes all kinds of folks, that old building has been sampled, lab tested, abated, resampled and retested complete with 8x10 glossies and a description on the back of each one. We are allowed to leave it undisturbed. I covered it with sakrete and will pour a slab over everything. Dang varmints.
About 20 years ago I was working on an old antebellum log home that had been used for awhile by the ladies as a place to do quilting. I found more quilt squares underground than you could shake a stick at. To have been a fly on the wall when they would get there and their pieces were gone :D
What about using Superior Walls?
I considered it, I like them. This thing is going to be so small I think the ding for delivery and setup will price them out... but there I go assuming. I'll give them a call when the plans are a little further along.
I've thought that after a hurricane or whatever we should be sending trusses and superior walls down rather than trailers.
We have more than a few PWF's in my area that were constructed 25-30 years ago that have held up well. Most are full foundations but do have poured floors. One of the most important things I found from the builder who did most of them was that backfill material must be porous so no moisture is retained. He typically backfilled with crushed stone or a coarse sand gravel mix.
I know of two houses with pressure treated wood basements built about 25 years ago(both were built by the same company). The current owners can't sell them. Banks won't give loans to buyers interested in them and one had their insurance dropped because of problems with the basement.