When strolling the beaches of the Washington Coast or even in the Puget Sound, it is quite common to come across beach logs that have been riddled with the tunnels of the Teredo Clam. The Teredo is a salt-water clam that eats wood and can be very destructive to wooden timbers like piers and wooden ships—and of course beach logs.
In Washington State, the Teredo (or Shipworm) is one of the wood destroying organisms that Licensed Structural Pest Inspectors are required to report on in homes. These critters are only destructive in wood that is still in the salt water and do not represent a “problem” in homes—typically. In homes we only see where they used to be in the wood prior to milling. In other words they got into the logs that were floated to the mills. When the logs were milled into boards we see the evidence of where they had been—as there tunnels are exposed on the surface of the wood.
Home owners and home buyers can find these large holes left by the clam’s activities disconcerting. They think the damage might be current, and affecting the home structurally. Most structural wood with this kind of damage will be “culled” at the mill prior to sale unless the damage is at locations on the wood that doesn’t affect it structurally—hopefully.
These pictures show some Teredo damage on the 2×6 subfloor of a home.
Charles Buell, Seattle Home Inspector
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