Q&A / 

Treated Wood Foundation Problems

termite damage treated lumber

Lookie lookie, Can you see the extensive termite damage on the right side of the post? Imagine my reaction when I pulled this treated lumber post out of the ground. I was told it wouldn't rot and that termites couldn't eat it. How would you like to have your foundation built out of this wood???? You'd have to be NUTS to take that chance. ©2017 Tim Carter

Treated Wood Foundation TIPS

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, Ohio 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've 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.

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Castle Clues

Have you ever seen photos of ancient castles in Europe? Often the walls are still standing, but the roof is long gone.

Treated Wood Foundation Problems

Here's an old castle in Germany. The masonry walls are still standing, but the wood roof structure is long gone. Wood never wins against water, insects and fungi. Copyright 2017 Kathy Ziprik

The roofs were made from wood. The walls were made from stone. They didn't have treated lumber a thousand years ago, but believe me the timbers they used to construct those castle roofs were the densest and most rot-resistant lumber available at the time. Water always wins with lumber if there's oxygen around.

Cast, or poured, concrete is artificial rock or stone. You can order it with more Portland cement and make it incredibly strong so it lasts hundreds of years if that's the legacy you want to create.

Wood Is Strong

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.

Insects & Rot

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.

Human Error

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.


The wood certified for wood foundations is supposed to contain a higher amount of the preservatives. That's a given. But how do you know if it does?

Do you want to hope your treated lumber foundation has enough preservatives? Hope is the emotion of last resort. You hope for things you can't control.

You can control your foundation. You can make your foundation wall last as long, or longer, than castle walls.

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Anger Issues

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.

Quality Control?

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's just good business. But mistakes do happen and I have proof.

How many food recalls or other product recalls can you remember in the past year or two?

How did those mistakes happen? Who was in charge of the quality control that day at the factory?

Impossible Test

The questions you have to ask yourself, since you can't easily test the lumber at your job site, might be:

  •  Is the treatment in this lumber the correct mixture and will it LAST?
  • Was the lumber mislabeled?
  • Was the correct amount of preservative used and was the pressure high enough in the vessel?

Tim's Failure

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.

Great Wonders Of The World

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.

Build your foundation from concrete and sleep well at night.

CLICK HERE to get FREE & FAST BIDS from local foundation contractors.

This column was mentioned in the May 12, 2015 AsktheBuilder Newsletter.

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