Wood foundation questions

After more than 1000 inspections, I’ve come across my first wood foundation today. The mud sill appeared to be treated wood, and relatively new. The sill supported a wood crawl space wall structure similar to a cripple wall. Large posts at the corners support double-girders.

Any issues to be aware of? Any disadvantages to this construction method?

101209 171.JPG

101209 171.JPG

Looks like it depends where the location is. I know Fire fighters didn’t like them for obvious reasons . They tend to fail faster.
Here is a discussion that was on here before


It look like wood skirting.

How were the wood corner support posts supported (footing-wise)?

No resemblance to wood basement walls we have around here. Always 2x6 (sometimes 2x8) 12" on center. How far underground is the wood? Does it have exterior plastic waterproofing?

I didn’t actually inspect this house. I viewed it for 5 minutes as a favor for someone semi-interested in the property. I immediately recognized that I had never seen anything like it and took some photos. The piers appeared to be creosote. The portions between the piers, I’ll call them a curtain wall, were wood. The bottom sill was treated, but was in direct contact with soil. I think the curtain wall only serves to keep possums out from under the house.

I don’t know how deep the piers went and don’t know anything about the footings.

I do know that all wood rots, even creosote, over time. I’d be wary of this building technique if it were me. I want a home that will last several generations…not one that will require new posts in 75 years or so. House was built mid-70s.

Crazy huh Joe?----:roll:

I certainly agree with you and the other posters…I certainly wouldn’t want whatever they have thrown together there either.

Is there no stem? Just beams laid accross the soil? I could think of many reasons this would not be right…but then again I am in CA.

That’s what I saw.

WOW!!! Must be like a hunting cabin or something. Does that type of construction fly in your world out there?

Wood foundations don’t need footings…their bottom plates serve as footings. They are typically bulit as normal stud walls, and the wood used is required to be pressure-treated far beyond the normal levels, and is usually only available by special order. The walls are installed on a gravel base, and the detail between the wood walls and the concrete floor slab is critical.

I’ve never used one, but I would if there wrre enough reasons to do so, such as a very steep property where getting concrete of blocks to the building site would be difficult.

I talked to another inspector who is also a licensed general contractor. He said in about 5,000 inspections in the Carolinas, he’s seen about a dozen of these structures. He emphasized that he life expectancy of treated wood in direct ground contact would be about 20 years. The home is over 30 years old, and the curtain wall between the piers has already been replaced.

In my conversation with the client this a.m., I informed her of the issues with wood and that future structural repairs can be anticipated at some point. “Have you ever seen those guys who work for the telephone company replacing telephone poles,” I asked? “They do that because the poles have rotted to the point that they are no longer structurally sound. That will happen with this house too.”

I told her to look for a conventionally built home.


4. Long Lifespan

Accelerated laboratory testing of modern pressure treated materials indicates a lifetime of over 100 years with no serious deterioration.

Durability of the systems has been amply demonstrated over the long-term by in-ground tests conducted over the past 40 years by various Federal agencies.

In addition, preservative-treated wood in these tests has withstood severe decay and termite conditions.

P.W.F. Self-Study Course
This is the comprehensive course that mirrors the information given in our seminars used to train building inspectors, contractors, renovators and tradesmen.

wood basement walls are permitted by all of the state and national building codes making them a an accepted building practice in all homes with the exception of the ones that i will live in

I would dispute that using common sense. And I quickly found this online referring to the lifespan of utility poles.

"With proper maintenance, **the average lifetime of a wood utility pole is typically 30 to 40 years **(Beyond Pesticides, 2005; AISI, 2005; Western Wood Preservers Institute, 1996), but as poles age, the effects of initial preservative treatments wear off and the preservatives must be re-applied (Wolfe et al, 2001). The majority of wood poles in service today has received, or is scheduled to receive, these repeat applications of preservative (WWPI, 2005). During the time a utility pole is in use, water acts as a medium for preservatives leaching from the wood into soils and groundwater. Leaching rates vary by both type of wood and chemical applied as well as by the standard of application. Researchers estimate that between 30-80% of the Penta applied to wood is released within the first year, but CCA-treated wood, on the other hand, is more resistant to leaching than Penta-treated poles (Bunce and Nakai, 1989; Zagury, et al., 2003). Leaching rates also are effected by the amount of preservative initially absorbed into the wood; the pH of rainfall and soil near the in-service pole; as well as the type of soil the pole is rooted in. "

Source: http://www.enviroliteracy.org/article.php/1311.html

Here’s another one…

“The wood pole’s lifespan is about 30-40 years. Sounding, drilling, and coring inspections give information about the pole’s condition.”

Source: http://www.psc.state.fl.us/consumers/utilitypole/en/AllUtilityPoleInfo.aspx

I second that emotion.

Joe I would not own any building with a wood foundation either. The link I posted is from a TV add that’s been running in my area. Thought it might be a little informative. My opinion is it’s just a matter of time before they’re out of business. :wink:

Regarding utility poles, it seems they would be more exposed to the elements than a properly installed foundation.