How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
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Do termites eat concrete?
Tuesday, September 25, 2018
There are plenty of amazing urban legends out there about termites. Let’s cover six of them:
1) When termites run out of wood, they start eating the concrete in your house.
Nope. Termites have a unique digestive system that allows them to process wood cellulose as food, but concrete is not on their menu. The illusion that termites have infested a chunk of concrete could possibly be created by termites crawling through very small cracks in a chunk of concrete to get to wood material behind it.
Also, some houses that have a stucco finish on the exterior walls look like they are constructed with concrete blocks, but they are actually wood frame construction with stucco siding. The photo below is an example of a home that had such a severe infestation that the panels under the stucco were beginning to fall off the wall.
2) Subterranean termites can mutate into drywood termites.
Not so. They are two separate species that split apart long ago on the evolutionary chart. Subterraneans live in the ground and crawl up into a house through protective mud-tube tunnels. They are more aggressive wood-eaters than drywood termites, which can start a colony in an attic and don’t require a moisture source in the ground.
3) Termites will even eat pressure-treated wood.
Semi-true. Wood that is treated under pressure with chemicals to resist rot is also required to be termite resistant—but it is not permanently termite-proof. There are two ways that termites can attack pressure treated wood:
- The pressure-treatment does not fully penetrate to the center of large wood posts. So, if the bottom of a post is trimmed off before it is buried in the ground the core is vulnerable to termites. Manufacturers recommend applying a second treatment of chemicals to a cut end before installing a post in the ground.
- The chemical treatment of wood that is unpainted and exposed to outdoor weather lasts about 8 to 10 years before it has mostly leached away by rain. Then the termites attack. If you look closely at the rating tag on pressure-treated wood, you will notice that some lumber is rated for “ground contract” and some is not. The ground-contact rated lumber has a higher level of chemical treatment and will resist termites for a longer period.
4) Termites bite like red ants when disturbed.
Wrong. If you have ever actually seen a live termite, this story is especially amusing. Considering the damage they do to a home, they are incredibly tiny insects. There are “soldier” termites that defend the colony against other insect attackers, but their miniature jaws would only hurt another insect and they do not sting.
5) Wood chip mulch in the yard attracts termites.
Definitely no. Research studies by both the University of Florida and the University of Maryland entomology departments found that, while termites will eat most varieties of wood mulch sold at garden centers during the process of underground foraging around a yard, it is not their favorite diet; and, the incidence of termites under areas of mulch was found to be no higher than under areas of bare soil or pea rock ground cover. In fact, the University of Maryland study found the most termite activity under pea rock. Wood chip mulch piled up to the base of a home’s exterior wood siding, however, does provide a concealed route for subterranean termites to enter the wall.
6) Termites steal marijuana.
Not sure. We got asked about this one a few years ago while working in Key West. But if it is true, they might be hungry enough after munching the marijuana to want some concrete.
While many of the amazing stories about termites are fiction, their ability to do major damage to your home is very real. Termites cause an estimated $11-billion in damage to wood structures every year in the United States, which exceeds even the annual damage caused by house fires.
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To learn more about termites, see these other blog posts:
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