Permanent Wood Foundation

[VoteQuimby]

I'm looking at a home with a PWF (permanent wood foundation) and wanted to see if anyone here has or has had a home with a PWF? From my research it appears proper drainage is key to maintain integrity, however from what I can tell the basement is extremely dry and I didn't see any signs of water wear on the wood.

If we make an offer I will obviously get it inspected, however I wanted to gather some opinions of people who have had a home with a PWF. Thanks!

 

[VirtualLarry]

I didn't know wood foundations were legal. Is this a tree-house?

 

[mizzou]

Ive never heard of this. How is this a thing??

 

[Meghan54]

From a page on InterNACHI's (International Ass'n. of Certified Home Inspectors) website:

When pressure-treated wood was developed in the 1960s, it became possible for wood to be used in foundation walls without being prohibitively vulnerable to damage from insects and moisture, and by the 1970s, permanent wood foundations (PWFs) gained acceptance.

Some builders and manufacturers claim that wood foundations offer a number of advantages over masonry foundations, such as: Wood foundations are simpler, quicker and cheaper to construct than masonry foundations. On average, they will not, however, last as long as masonry foundations and are less durable in the long-term.

http://www.nachi.org/permanent-wood-foundations.htm


Personally, unless I was buying in AZ or NM, I think I'd stick to some sort of masonry foundation, considering the bolded sentence above.

 

[DrPizza]

An acquaintance built an entire home completely by himself, including an all-wood foundation (though, sitting on a concrete footer). It certainly was simpler and quicker to build. Material-wise, I don't think it's cheaper - the cost savings comes from the savings in labor. Unless I'm mistaken, it calls for marine grade plywood, not just ordinary pressure treated plywood. If I did it, I'd want the plywood also made of larch, which alone has some excellent ground moisture contact properties. But, marine grade plywood runs around $80-$100 per sheet for 3/4" to 1". That's 32 square feet for $100, not including the studs to support it. By comparison, it would take roughly 2-3 dozen masonry blocks to cover the same area. If you used 16"x12", it would take 24 blocks, which at HD's prices (quickest reference), are just a little over $2 each, or $56.68 for 24 at the current price. (It would cover slightly more than 32 square feet, since there's mortar between blocks; mortar is pretty cheap too. Rebar for the block/studs for the plywood, and material wise, those come close to evening out. I'm not sure what the expense is of spraying the outside with a heavy duty water proofer is, but it should be done to both.

I would NOT buy a house that had been built by a contractor with an all wood foundation, unless I was absolutely certain they used a high quality marine grade plywood. Too many builders seem to cut corners to make more of a profit. Regular pressure treated plywood simply doesn't last long enough in contact with the ground.

 

[Greenman]

I read about wood foundations years back. I've never seen one, and wouldn't own a house with one, and don't really see why anyone would do it.

 

[Red Squirrel]

I've heard of this, and there are proper ways and a certain science to making it work, I heard it can last very long if done right. But personally, there's no way I'd do it. Poured concrete with proper weeping tile and sprayed on rubberised sealant is a much better way to go imo. It's one of those things I'd probably leave to pros as well if in the process of building a house.

 

[SparkyJJO]

I read about wood foundations years back. I've never seen one, and wouldn't own a house with one, and don't really see why anyone would do it.

This. No way wood I want that (har har).

 

[Mandres]

Although it may be allowed, I would never put wood in the ground for a permanent structure. It's the fundamentally wrong material for the job, and you're relying solely on the chemistry of the glues and preservatives at that point. I'm sure builders love the idea because it sounds cheap and easy, but that's a risk I wouldn't ever take.

 

[RU482]

damn, masonry or concrete foundations have enough problems, I can't imagine how aweful a 20 or 30 year old wood foundation would be.

Oh wait, yes I can, I have a pole barn from the 70's with rotted out posts

 

[K7SN]

damn, masonry or concrete foundations have enough problems, I can't imagine how aweful a 20 or 30 year old wood foundation would be.

Oh wait, yes I can, I have a pole barn from the 70's with rotted out posts

They last longer than 20 or 30 years but moisture is the biggest enemy in the old days. If rocks weren't available, houses were sometimes made out of old railroad ties (creosoted) and I've seen standing houses, still solid foundation, over 100 years old BUT I wouldn't want to live in them for the rats and mice, not the house. These are in the desert where the it is dry 10 feet down 350+ days a year. The newest pressure treating methods may have solved that but then even modern concrete wears out.

 

[stockwiz]

Some people claim they are far superior to masonry and having been in one I can tell you they are easier to insulate, and split foyers built with them have nice, cozy lower levels with no musty smell. However they are hard to inspect for bowing or rot as inspectors aren't going to tear apart finishing to check the status of the foundation... they only inspect what they can visibly see... so I personally would not trust one myself... I didn't even know they existed until the realtor pointed it out to me on a house I actually put in an offer on, and the sellers didn't accept, but countered with an offer $3000 higher. When I saw it had a wood foundation I was sort of glad they didn't accept my offer and I was able to back away from the deal without repercussion. Lesson learned.... wood foundations exist... they are quite rare around here. As far as I know they only exist in this one development done in the early 1980's, and only about 20% of the homes have them, so maybe 1-2% of the homes in the town were built with them.

With that said it's possible that the foundation is fine and there's no bowing and no rot... the basement was cozy and smelled fresh without a dehumidifier and the small exposed section I was able to see didn't seem any worse for wear.. then again it's possible I might win on a keno machine when I go to a casino... the question is do I want to take the chance, and do I want to pay full price on a house when wood foundations are generally frowned upon assuming people even notice before putting in an offer?

 

[pcgeek11]

I can't belive they used the words " Permanent " and " Wood " together in a sentence.

That is just stupid.

 

[stormkroe]

I've built several of them, they're quite popular in Alberta. Doc is right, it's not plain pressure treated, but rather 'PWF' (Preserved Wood Foundation) that is rated for direct earth contact. While it used to be impregnated with arsenic<!>, now it's a saline mixture for environmental issues.

Anyway, when done properly, the wood should NEVER come into contact with moisture, as it is tarred, will have 'peel and stick' applied, or a breathable, hard plastic 'bubble' covering that is all layered to continuously shed water all the way down from your soffit into your weeping tile.

Fun fact, while 99% of the time they are sitting on concrete foundations (must extend 7 inches past the wall on both sides by building code), it's actually legal to place them on sand. Sadly, I'm not kidding.

Now with that out of the way, I'll go ahead and say this: there is no reason (even cost lately) to go with ANY other type of basement than ICF these days. Nothing even compares to it in any way, except cost, which is getting better all the time.

 

[IronWing]

Personally, unless I was buying in AZ or NM, I think I'd stick to some sort of masonry foundation, considering the bolded sentence above.

The termites would eat it faster than rain could rot it. I can't see using a wood foundation in any warm climate. I think stormkroe's reference to Alberta is spot on for a climatic sweet spot for this.

 

[JEDIYoda]

I can't belive they used the words " Permanent " and " Wood " together in a sentence.

That is just stupid.

actually nothing really permanent!! Thus the word - permanent is just plain stupid!