Termite Damage – How Old?

By Chris Williams on July 22, 2011.

Q. We’ve been living in our home for 5 years and just discovered that we have termites. Apparently they’ve done a lot of damage and we think they were already at work on the house when we bought it, and that the previous owners should be responsible. Is there any way to tell how long termites have been infesting?

A. Not really. Lots of experts (and lots of lawyers) have tried to come up with a formula. It’s more art than science to estimate the number of years a home has been under attack by termites. In theory, you could accurately estimate how many years termites have been feeding in a home if you knew (1) the wood consumption of a typical termite worker over a one year period, (2) the average number of termites actually feeding on the structure, and (3) the amount of wood that has been consumed in the home.

An average colony of eastern subterranean termites contains approximately 300,000 workers. Laboratory studies suggest that a colony of this size can consume approximately 22 linear feet of a  2×4 in one year. This is equivalent to about one cubic foot of wood. Unfortunately though, these are lab studies and termite consumption rates have not been studied inside structures.

termite-damageIn the real world though, there are many more variables that affect the calculation, including the age of the colony, the type of wood, the moisture content of the wood, the harshness of the winters, and availability of other food sources for the colony.

It’s often easier to use your knowledge of the history of the house to make guesses about the age of the damage. For example, if you know the damaged area was painted two years before you moved in and an inspector finds that the paint has seeped into and filled termite tunnels in the damaged wood, then the damage must have already been there when the painting was done.

Renovations or changes to the house can give clues since termites often infest from areas that have been disturbed. For example, say the garage was turned into a family room 10 years ago.  If the existing infestation seems to have originated in that area, it would seem likely that the infestation began after the renovation.

Again, though, these are just guesses based on our best knowledge of termite behavior. A leading termite researcher, University of Maryland’s Dr. Barbara Thorne said, “The unsatisfying but realistic conclusion is that termite feeding rates are highly variable and cannot be reliably used to predict feeding rates in an unstudied population or to retroactively determine the length of time that termites have been in a structure.”

My best advice: Don’t wait on the previous owners or the legal system to come up with an answer before you take care of the termite problem. Your house won’t fall down tomorrow but you shouldn’t ignore an obvious termite infestation. Call Colonial. We can help.



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