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In my area, the lumber yard seems to be pressing them, and after talking to three people I know who have them, they all say the same thing. They'd never have anything else. So, I went to the next lumberyard seminar on wood foundations, and I must admit that, biased as the information was, it didn't seem like a bad idea. I don't know if I'd jump right in and start building houses that way, but I'm certainly going to keep it mind for the next addition/garage that comes up. The points they made had some merit--in our area, we see a lot of hairline cracks within six to twelve months--bad concrete and labor/prep? Could be, but we also have a large amount of clay and hydrostatic pressure. I don't know, what kind of information did you have?
*Jason, If expansive clays are crushing properly reinforced concrete walls. You can bet that it will crush a wood foundation wall. People are slowly coming to realize that wood is a temporary building material. The growth in ICF housing is phenomenal. So many people are changing from wood to concrete for above grade applications. It is my opinion that a wood foundation is a step in the wrong direction.
*The driest and most comfortable basements I've been in were done with treated below grade wood foundations. If I had a sloped site, with soil consisting of mostly sand or gravel, I'd select the wood foundation over concrete. If I had 7' of clay or poor draining soil I'd stick with concrete. Wood foundations have been around long enough now to see what's working and what isn't.
*I put a rather complicated split level hillside wood foundation on our home and I am a non-professional. So far (8 years) so good. Our lower levels are 100% finished space and we have never had any evidence of water damage. The key is lots of drainage under and around the foundation. To complicate things, we also put a garage over living space (over the wood foundation) with 2 1/2" of concrete over a heavy wood floor framing. So far, not a single crack in that garage floor!Our lumber yards are beginning to stock LESS of this material than they were a few years ago so maybe people are being scared off by the non-permanent perception of wood. Of course, they never consider that concrete isn't permanent either. I've been in a lot of 50-90 year-old block basements and only 1 in 10 are dry enough to merit being turned into comfortable living space.One suggestion: look into using galvanized nails on the treated wood instead of stainless steel. My handbook showed stainless steel and we must have spent at least $500 on nails. Since then, I've read that good galvanized may have been adequate.I live in MN and we have sandy soil.-Randy
*Well I've seen a fair number of these and for the following reasons wouldn't have one in any house I was associated with.They are more sensitive to correct installation than cmu or pour.Due to their poor reputation resale value isn't as good as concrete.Go back in the archives about a year ago. There was a pretty long and involved discussion on this. The upshot was that although they could be as good as cmu or pour they couldn't be any better and there were enough downsides that they shouldn't be used.
*Well, I for one appreciate the input. I'll go back to the archives and check them out. I know that in my area, they are gaining in popularity, not lessening, so I need to be at least knowledgeable about them.
*Jason,Wood foundations are also gaining popularity in my area and even more so in northern Michigan. I spent about two years researching them before I decided to build one and I couldn't be happier. My homesite was mostly clay and had a high backfill height. Using 2x8 walls with appropriate framing connectors at the top plate and floor joists to aid in resisting the backfill loads on the structure. I also spent an extra $400 and wrapped the foundation with Grace Ice & Water shield before I applied the 6 mil poly sheeting. Backfilled up about 36" with pea gravel and the rest of the way with well draining sand.I also insulated under the concrete slab with 1 1/2 inch dow board.The basement is dry and warm consistently throughout the year. I've even had a few of my buddies who pour walls for a living comment on how nice the basement is. I'm not saying PWF's are for everyone, but as with any alternative process their will always be skeptics. I think engineering and proper drainage are critical to the long term success of these foundations. With the moisture barriers and stone/sand drainage I've installed, I find little merit in the comments about the wood in the ground not lasting for the long term.
*Ron. Were the W.R. Grace Ice & Water Shield and the poluethylene both necessary. did you also seal all the plywood butts and loints? Did youi also install a vapor diffusion retarder (VDR) on the interior? GeneL.
*Gene,Only 6 mil poly is required as a vapor barrier. I added the Grace Ice & Water as extra insurance. I already had the 6 mil on hand, so I used that as well. All plywood joints were sealed with elastomeric caulking. 6 mil poly was installed on top of the foam insulation, before the concrete slab was poured.
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thanks for t info everybdy. ive been framing for 13yrs and only . if the wood can hold the earth up if it leaks wouldnt it be easier to fix,+ it wouldnt crack.im going to build my first house tolive in.i could save $$$ framing my foundation.i think big. 2x8 12"oc 3/4 ply + the best water proof system avaible. later Jack of none master of one.
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what do u think