Wood Foundations?

ebass · May 18, 2005, 09:45:08 PM

Hi everyone:

Have found a few sites about wood foundations....
Anybody had any experience with them or know anything about them?........
Thought that it would be a nice way to eliminate the need for concrete and still end up with a basement, IF (big "if" here) they are relatively easy to construct and (even more important) they hold up over time (many decades).....confess to being somewhat skeptical about them, but don't want to pass judgment unless I get some replies.......

Thank you,

ebass

John Raabe · May 18, 2005, 10:46:53 PM

I did research and designed a wood framed basement foundation for the Universal Cottage (it could be used in any of the other houses as well). PWF foundations can be a bit complex to design (primarily as it adjusts to backfill height) but relatively easy to build and when done right with good drainage and water barriers will last as long or longer than concrete basements.

If all concrete basements were built with the same attention to drainage that goes into a PWF foundation they would last longer as well.

The primary advantage of this option is when the space will be insulated, wired and used for habitable space. PWF foundations are also good for owner/builders as they use the same framing tools and skills used above grade. You do want to be careful about about cutting and dealing with the cutoffs of PT lumber.

Here's one of the best links: http://www.southernpine.com/pwf.shtml

May 19, 2005, 02:19:49 AM

This is very, very intriguing. One of the stumbling blocks I have to building is the foundation and my reluctance to "farm it out." This seemingly would allow me to build it myself, assuming the engineering was professionally done.

Can wood foundations be used for larger structures, say a non-pole barn that would normally be built on a concrete foundation?

glenn kangiser · May 19, 2005, 02:26:00 AM

My cabin is 2050 sq ft. buried- not your usual govt approved corporate blessed model - but it is a generically engineered design and definitely works.

Either that or I'm dead right now and don't realize it. Someone pass me down a glass of water, please. :-/

MARK BROWN · May 19, 2005, 06:00:29 AM

I did it, I bought a design manual, actually two of them and gave one to the building inspector. Had to order everthing special, it is kiln dried, treated and then kiln dried again and the woood is 0.6 pounds of treatment per ft. cubed of wood. and the fasteners where 316 stainless steel. it worked out fine, in fact I studded out the whole house out of pt wood, kiln dried. so take a hike bugs and sorry to the firemen if it ever burns down.

Mark

May 19, 2005, 07:24:57 AM

Thanks for that information Mark. Did you have a basement? Concrete floor or footings?

jraabe · May 19, 2005, 09:49:07 AM

Mark is doing it right. Stainless steel fasteners and foundation grade KD and PT material. Follow this up with a drainage plane and a protected water barrier and even Glenn could be resurrected

and returned to the land of the living!

PWF foundations can be done for almost any type or size of building when you don't want to call in the cement mixers. I've been including information on this in plans for years yet very few people actually get the idea and put it in action. Foundations made out of (poured) rock are a difficult idea to let loose of, I guess.

You can use these commonly available materials to build everything from the PT skid foundation for sheds and playhouses that I did for the Enchilada kit, up through simple crawlspace or slab on grade options such as this one I posted a couple of years ago at the old forum:

and on to the full basement foundation of the Universal cottage. PT basements have obvious advantages over concrete in small houses — walls are the same thickness above and below grade so stairs are easy to build. Floor area is not used up by a furred in interior wall for insulation and wiring... I could go on.

Do a search of the website and old forum on the term "PT foundation". You will find lots of discussion and ideas.

ebass · May 19, 2005, 06:06:19 PM

Would plastic and wood composite lumber have any advantage over PT or KD lumber anywhere in this type of construction?..........

Sooo Glen, I didn't know you had a career in films......didn't I see you in that remake of the 50's thriller "Night of the Living Dead"?

........(sorry, bossman!......just kidding!)

Seriously though, thanks to all of you for the posts.......your expertise is always appreciated....

ebass

jraabe · May 19, 2005, 08:04:28 PM

Interesting question ebass.

I don't know of any work that has been done
with composite or plastic lumber where it has been used structurally.

Doesn't mean it couldn't.

That's all engineering is — "let's keep putting weight on one end til it breaks." or a slightly more sophisticated version of "that blowed up real good!"

glenn-k · May 19, 2005, 10:26:46 PM

Ebass. as I have proven once again tonight-- I must return to my native soil before the sun sets - if possible or people have to put up with me being a nervous ornery troll.

John, I was in the city today working on the new federal courthouse-- I dealt with foremen, project managers, inconsiderate people -hoards of people who don't drive like I think they should and I have a request, ---- if I have to be resurrected, please don't let it be in the city. :-/

The only thing worse than having to work there today is having to go back tomorrow. Sometimes I make myself sick - selling myself for money like that. Please don't call me tramp or whore.

ebass · May 21, 2005, 03:40:01 PM

Hi everyone:

Got a few more questions about PWF/ PT basements......Does anyone know of a good, thorough design and construction manual that will take a first-time builder step by step through the process?......
Have checked suggested sites and found lots of good pictures, technical and professional info, but not enough info packaged to educate me as an inexperienced, 1st time DYSer..........

Are there any construction modifications that must be made in consideration of climates.......such as New England?........or any other parts of the country?

Also, what is considered to be the best water barrier material and how would a water barrier be properly attached to the outside of the PT studwalls?.....It seems that punching holes in it by stapling or nailing would be counterproductive......would some type of adhesive be the way to go?........
Could a concrete floor pour be completely eliminated?

Thank you,

ebass

Greenbank · May 21, 2005, 05:34:38 PM

I have a question, too, about the "healtiness" of a full basement which is essentially a PT lumber box. I assume there aren't any issues as long as you're not actually chewing on it, but I'd like to know for sure.

John in NYC · May 21, 2005, 07:18:45 PM

First keep in mind the triple reduncancy of the PWF foundation. It starts with a lumber stress skin panel wall made with material that is highly rot resistant. Then, a waterproof memebrane is placed on the outside of that wall (many builders use standard 6 mil block poly, but I useually spec out TruTuff cross laminated poly). Overlap the joints but put it up with staples. Third, you back fill the wall and drain the footing so that no hydrostatic pressure can build up against the wall.

You should not build a wall without this drainage plane and if you do you don't need to worry about such small things as staple holes.

On the interior put up airtight drywall and/or 6 mil poly vapor barrier. Any concern about the chemicals in the wood treatment process are thus isolated.

There are no climate adjustments that I know of for PWF foundations as the soil environments are pretty similiar. Local builders will no doubt have special tricks and techniques that they like better for the local siturations. However this is true for all building techniques and tools - otherwise what would you have to argue about in the taverns after work?