Treated Wood Foundations
Summary: Treated wood foundations can be used when you build a new home. But wood foundations may not last as long as a concrete or concrete block foundation. A permanent wood foundation must have the right mix of chemicals to ensure it never rots or is eaten by termites.
DEAR TIM: Several years ago, there was a movement toward the use of wood foundations due to the rising cost of labor and concrete. I toured a couple of newly constructed homes in the Toledo area at the time that had used this technique.
My question is "How have these structures fared over time?" Are they still considered sound and what has become of the idea of wood frame foundations? Are there any contractors using this method actively today? At the time I thought it a good idea, but being the skeptic I am I thought it was better left to someone else to prove the concept. I have built several homes over the years (for my own use) and have given thought to another project. Your thoughts and insight are always appreciated as I am an avid reader of your column in the Toledo Blade. Roger Puppos, Toledo, OH
DEAR ROGER: I absolutely remember that movement promoting wood over masonry for foundations. The thought back then that rushed through my head was the fable about the Three Little Pigs. As many of us know, the big bad wolf ate two of the three little pigs - the ones that used straw and wood to build their homes. The pig that used masonry was not harmed by the wolf.
My problem with the wood foundations was never one concerning engineering. I was convinced a properly constructed wood foundation could easily act as a retaining wall against all soil pressures that were trying to push it over. Wood shoring has been used for years to protect workmen who install piping in deep trenches and those who work in mines.
I have no doubt that the treated wood manufacturers still promote wood as a viable material for foundations. I also believe there are builders who still use wood for foundation work.
My real concern was long-term degradation caused by water and insects. The thought that kept playing in my head like an endless loop of video tape was an image of a workman at a plant that makes treated lumber. There were two episodes in this short documentary. The first one was of the workman coming to work with a very bad head cold or the flu. In this episode, he starts to blend the chemicals that are used to preserve the wood, but because of his lack of concentration he makes a serious mistake and that batch of lumber does not receive enough chemical treatment.
Episode two is a little different but the result is the same. The workman who mixes the chemicals goes and asks his boss for a raise. The plant manager tells the worker that he is not deserving of a pay increase. The disgruntled worker goes back to the work station and decides to take his anger out on the next load of pressure treated lumber.
I don't doubt for a moment that plants that make pressure treated lumber have quality control measures in place and follow them making sure mistakes don't happen. That is just good business. But mistakes do happen and I have proof.
In the early 1990's when CCA treated lumber was still being produced, I built a large play structure for my daughter. The main supports were 4x4 posts that I placed directly into the ground and backfilled with the soil. These posts were approved for direct ground burial. The treated lumber came with a lifetime warranty against rot or decay.
Fifteen years later, I took the play structure apart so I could build a large Queen Anne Victorian garden shed for my wife. To my amazement, two of the six 4x4 posts had significant termite damage to that portion that was buried in the ground. To say the least, I felt vindicated about my suspicion that treated lumber was not to be trusted 100 percent of the time.
When it comes to building for a lifetime, I have a tendency to lean on my college degree in geology. Look at the great temples, tombs and castles that are still standing in the world today. One thing they all have in common is they all are made from rock. The Great Pyramids are still standing after thousands of years as are temples in Central and South America. Europe has castles that are hundreds of years old that are still in excellent condition. Remember, concrete is nothing more than artificial rock.
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Comments:
Derick 03 Apr 2008, 23:14
Tim,
My wife and I are recently married and looking for our first house. We came across a whole neighborhood of these wood foundations, and I could only be skeptical. After doing a little asking around and some research I feel it would be very wise to stay away from them. Thank you for the insight. Derick- Indiana
charae fidanza 13 Apr 2008, 00:52
we have already purchased a home with a wooden basement. we have a solid
concrete floor. our home was built in 1971. we now have to do something
about the walls. the house sits on a hill. so only about 3ft is above
ground. should we pour or block the walls. right now ther are 2x6 braces
made of wood about every 16in. from floor to ceiling. there is water ran
down there and electric. had engineer come and inspect and he said we
needed to have the basement fixed.
Lyn Classy 06 Jun 2008, 07:20
We are doing a rat wall around a deck using wood 2x6 boards with a stain on
them to treat the wood. Going 6" down there is a fountain under the deck if
we dig 6" down will the rats go farther down.
greg 05 Sep 2008, 13:54
I lived in a wood foundation community for about 12yrs(Fort Wayne, In). I
have to say, it was a pleasant experience. No cracked drywall, and no
dampness in the basement. The problem came when I went to sell the place.
Concrete is just the norm and many people don't even want to get close to a
wood foundation. In the long run it sold, but it did take some time. Just
be aware of these pitfalls up front!
Brian C. 05 Sep 2008, 14:47
Mr. Carter,
I don't think you gave wood foundations a fair shake in your comments above. Now really, the three little pigs? Disgruntled employees? Could happen at a concrete block facility too. Granted the castles of Europe are still standing as are the pyrimids in Egypt. One word. Crack. How many times have you seen cracks in a poured or cinder block foundation wall that was less than five years old? How about one year old? I built my homes foundation in 1987 with marine grade, .60 2x8's and plywood. The main reason was I can build a stud wall but I can't build a block wall. I am still most happy with my decision. Finishing was tons easier. The basement is dry. Warm in the winter and cool in the summer. In Minnesota we don't worry about termites. I tared the plywood and installed two layers of greenhouse grade polyethylene along with proper tiling and have had no troubles doing it again. In fact I am investigating having a home moved onto my property for a rental unit and intend on using wood as the foundation.
Walter Velichko 06 Nov 2008, 05:58
Will a 4x4 pressure treatedm wall hold a bowed concrete block wall in place
if supported by rebarb and jack posts?
Claude Holloway 09 Feb 2009, 19:23
In this article you stated that the 4X4 posts "were approved for direct
ground burial. If you bought these at a lumberyard, they probably weren't.
The lumber sold at retail outlets normally is not approved for contact
with the ground. The treatment required for lumber in contact with the
ground is approximately twice the strength of regular treated lumber, and
is the same as the tratment used by utility companies for their CCA poles.
Cheryl 06 Apr 2009, 20:36
I own a home that has the wood foundation I am having water and mold
problems now. how do I remedy this problem?? can I build some type of block
foundation wall from the inside of my basement?
Ginger 12 Apr 2009, 06:22
Recently looked at a home in a neighborhood that had all of the homes built
with wood foundations.
Huge mistake, originally the home was listed 6 months ago at 154,000 and because of no interest it had dropped in price to 79,500. The problem was the foundation. It was horrible for a 12 yr old home. The wood was completely rotted with dampness and moisture which had gotten into the walls and mold which was not fixable. The bank selling the home said they would have a concrete foundation put in. But they wouldn't replace the drywall. This is not a good choice for a foundation unless you plan on replacing it every 20 yrs. Now if it were in a dryer state I might think it would be acceptable but it is in Indiana.
BG 01 Jun 2009, 12:50
As with any technology there are many different sides to a story. I
disagree with the post in soil as evidence of decay of pressure treated
lumber given the application. THat post was not installed per PWF
guidelines but was in direct contact with soil; therfore moisture and wood
destroying organisms.
It seems the folks that had trouble are in wet environments. I installed a PWF on a deck containing a hot tub and sauna in CA where I received on average 18" of rain per year. However, tub overflow made for a much more wet environment. I installed 2x6 walls with 1/2" plywood sheathing, framed 4' high. with about 6" of gravel underneath, and 5 6" borings filled with gravel, plastic sheeting surrounding the plywood, I experienced no deterioration in ten years of use. Too, even with all the moisture inherent in a hot tub (old redwood), the subfloor area remained dry and comfortable. I think as with anything, PWFs are application specific, and with proper design and installation can work well. View all comments |



