I feel sorry for the wood foundation. Not because it’s terribly unsound – because it’s not. Not because it’s known to settle or have chronic moisture problems, because that’s not true either. I am not sure where it’s coming from, but we commonly hear concerns about the wood foundation from home buyers. I have even seen home buyers walk away from the purchase when I made them realize it was a wood foundation and not a poured concrete foundation as they thought it was.
In case you didn’t know; accelerated laboratory testing of modern pressure treated materials indicates a lifetime of over 100 years with no serious deterioration, and the 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.
A 100 year life expectancy or not, I have personally inspected thousands and thousands of homes – several hundred of them with a wood foundation. So let me share some facts based on my experience:
- A block foundation is much weaker, and fails at a much higher rate in our area than a wood foundation
- A poured concrete foundation will crack from settling or pressure from the soil, and it’s common to see water leaking through these cracks. Poured foundations also commonly start leaning due to pressure from the soil
- It is very important to keep water away from any foundation, not only to prevent from moisture intrusions in the basement, but also to take pressure from your foundation. You do that by having a positive slope away from the foundation (dirt, concrete slabs etc. should slope away from the foundation wall – NOT towards it)
- I can honestly say that I have seen less than five failed foundations built with wood. What’s common with all of them has been excessive negative grade over several years
- We have no contractors in our area specializing in repairs on wood foundations. Simply because the demand is very low or not present
We don’t know exactly how long a wood foundation will last, but we know that the most common options to wood are poured concrete and concrete blocks, and I have seen those foundations fail in homes ranging from 10 to 50 years old.
My final conclusion is: wood foundations are probably not any worse than any other type of foundation as long as you keep the water draining away from the foundation