Subterranean termites require a dark, damp environment. In their search for food, worker termites build shelter tubes (tunnels) that help conserve moisture and shield the termites from the light. (See FIG. 8-3.) The tubes are about 1⁄4 to 1⁄2 inch wide and provide a passageway between the ground and the food supply (wood member). They can be built at the rate of several inches per day and are mainly composed of soil, wood particles, and termite excreta. Shelter tubes, which might be noted on foundation walls, on the outside of wood framing, or even freestanding between the ground and an overhead pipe or beam, are visible evidence of termite infestation. If the tube is active, worker termites will be busy using it to go between the nest and the house. By breaking the tube, you can see the workers, who will try to repair the break. They are about 1⁄4 inch long and have a whitish cream coloring.
Some tubes might be abandoned. If you find an inactive shelter tube, it does not mean that termites are no longer in the house. It might, if the house has been termite-proofed. However, if it has not, even an abandoned shelter tube, no matter how small, is sufficient evidence to consider termite treatment. Many shelter tubes emanate from a nest. There might be an active tube inside the voids of a concrete block wall that would not be visible during an inspection.
Straight Antennae Elbowed Antennae
Whether a new building will be attacked by termites depends on the surrounding area and to a large extent the builder. Certain construction practices tend to increase the probability of termite attack. (See FIG. 8-4.) Some builders have been known to bury tree stumps and wood debris near the foundation or below the basement-floor slab. All stumps and debris should be removed from the building site. All form boards and scrap lumber should be removed before the excavated area around the foundation walls is backfilled. There should be no buried wood around the house. Otherwise, it can provide a source of food for a new termite colony that when it becomes large enough, will attack the house.
Most often termites enter a house by eating their way through untreated wood members that are in direct contact with the ground. Some of the more common points of entry are garage door frames, basement windowsills, wooden steps and supports, wood sills, and headers and studs on foundation walls that are located at or below grade. A particular area of attack is the wood framing adjacent to a concrete-covered, earth-filled porch, patio, or entrance slab. (See FIG. 8-5.) If there is no earth or wood contact, termites can build shelter tubes to provide passageways from the nest to the wood framing in the structure.
Some homes have a strip of metal (termite shield) between the foundation wall and the sill plate, that rests on top of the foundation wall. The purpose of the termite shield is to act as a barrier between the nest and the food supply. In most cases, the termite shield gives the homeowner a false sense of security. The shield does not prevent infestation. It only deters an attack. The problem is that the termite shield is rarely installed properly. An opening at a seam or a hole as small as 1⁄32 inch is large enough for termites to pass through. All seams should be soldered, and any holes around bolts and pipes should be filled with coal-tar pitch. Even if you see a termite shield, you should look for termite infestation.
Inspection A complete subterranean termite inspection consists of an interior and exterior check of that portion of the house that is close to, or in contact with, the ground. The exterior termite inspection can be performed concurrently with the normal exterior inspection as described in chapter 1. As you walk around the outside of the house, look for termite shelter tubes along the outside foundation walls. In many homes, this area is covered or partially blocked by shrubbery. Part the shrubbery so that you can see the wall. This is especially important for areas just below a garden-hose spigot.
|Direct Access from|
|Porch Fill to Wood|
|Entrance Slab||Termite Tubes over Surface|
|in Dirt Fill|
Fig. 8-5. Termite colonies can develop in buried wood debris and gain entrance into a building, particularly at earth-filled concrete entrance slabs or patios.