Preserved Wood Foundations

[Sparweb]

Does anyone reading this forum have any experience with Preserved Wood Foundations? The building in question is a 1350 sq.ft. bungalow. I've never looked at this kind of foundation before, and I can't seem to find people to talk to who aren't selling them - therefore with vested interests.
How long do these things last? I've collected some data on it, but estimates of life vary, and all exceed the amount of time that has elapsed since the first one was ever built!
What are they vulnerable to? Presumably all the things that eat normal wood, just slower?

Thanks, in advance. (I hope I've picked the right forum for the question)

STF

 

[ERV]

SparWeb,

As long as the wood members are not affected by water, than they will last practically last forever. The following considerations should be made:

1. The foundation should be set on crushed rock or gravel. This base should be the same size and depth as any other foundation would be (e.g. 12" x 12&quot, and provide continuous support for the wood members.
2. The exterior grade should be sloped away from the building, with a minimum slope of 1/2" per foot.

See also Section 1810 through Section 1814 of UBC 97 for other specific requirements.

I have considerable experience with wood foundations and have found that using the proper materials and adequate drainage is paramount for survival of the members. I have inspected wood foundations (foundation redwood) that were over 100 years old and appeared as the day they were layed. I have also inspected many that were severely attacked by fungus due to excess moisture (20% or more), that didn't fair too well.

 

[jheidt2543]

You might try checking the USDA Forest Products Lab website for information on wood foundations. Also, don't forget to check your local building and zoning codes, not all jurisdictions allow them.

 

[Sparweb]

I finally found an inspector in town that's very familiar with these foundations.

Grading is a concern at this site - as it was on a previous inspection in 1999, too. Between the house and the garage, the grade is virtually flat...

I got under the raised basement floor and peeked around, and it looks okay so far...

Thanks guys - I'll keep you posted, if any interesting issues come up during the inspection.


STF

 

[boo1]

check site:

http://www.pwfs.com/Page1.htm