How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
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What attracts termites to a house?
Monday, May 11, 2020
Wood attracts termites to a house. It’s what they eat and it’s that simple. There are two main types of termites that infest homes, subterranean and drywood, and each has a different search tactic when trying to find the wood to consume that is necessary to start a new colony.
Subterranean termites live in the ground because they need its moisture to survive, and cannot live for long if exposed to dry, open air. So scouts spread out underground in all directions from an existing colony, searching for wood that is either laying on the ground or touching it, to tunnel into and begin eating their way upward. Any wood they find is a pathway for subterraneans to get into the the home.
“Subs” can also explore above the ground; but to do it they must construct mud tubes, which are tiny tunnels they travel through that maintain the moist atmosphere they need while searching. The building codes require a 6-inch distance between any wood in a house and the ground, and that gap between the bottom of siding and the ground, for example, creates a no-mans-land that the termites have to cross with a mud tube that provides visible evidence they are trying to attack your house.
Anywhere there is not that visible gap between wood and the ground is a place that termites can enter your house undetected. Wood siding that touches the ground, or touches a layer of wood mulch or gravel on the groud, is one obvious example. But a wood trellis or planter box up against the house, or a gap between a stone veneer that extends underground and a wood wall (shown below) is another.
They can also extend mud tubes up on the piers under a home with a crawl space or a crack as small as 1/32-inch in a concrete floor slab on the ground. To get an idea of how tiny they really are, view the short video below.
In the photo below, they came in through an opening between two slab pours in a garage. Fortunately for the homeowner, it was a dead end for them—but also an indication that there is termite activity under the house and they may have already entered at another location.
The first sign that subterranean termites have a found a way into your house is usually seen at the baseboard of an exterior wall. Because they eat right up to the paint finish, but not through it, tapping or lightly probing the wood for soft spots may turn up evidence, like in the photo below, that it’s time to call a pest control company.
Drywood termites do not need water in the ground. Moisture in the wood is enough for them to survive. Drywood colonies are usually not as large as subterranean, and the consume wood at a slower pace, but can still do plenty of damage. They can live in almost any piece of wood, but are most often found in an attic, crawl space, wood paneling or trim, or even furniture.
Existing drywood colonies send out a swarm of winged termites and new queens each spring, usually on a cool morning or early evening. They are not good fliers and don’t get far unless it is a windy day, but typically enter a home through a gap in wood siding, around doors or windows, or an opening in the soffit or around a roof penetration, such as a chimney. They can also come into the house on an infested piece of furniture.
So the three best strategies to keep away termites—that will always be snooping around your house and looking for way in—are to keep any wood at least six inches off the ground, seal any openings in the exterior, and regularly check for the telltale signs that they have already found their way inside. A thorough inspection by a licensed pest control operator every year or two is also a good idea.
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To learn more about termites, see these other blog posts:
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