Subterranean termites inhabit the ground-soil where workers often encounter the foundation of homes while foraging. Unlike drywood and dampwood termites that only see winged swarmers (alates) initiate infestations in homes, subterranean termites see only workers infest homes from the ground up. This is why drywood termite damage is often found on roofs, in attics and in wood siding, while subterranean termite damage is typically limited to substructural wood components that are near the ground surface. Subflooring, beams, sill plates, sheathing and other substructural wood sources tend to see the greatest damage from subterranean termite infestations.

Since subterranean termites cannot tolerate the relatively dry outside air, workers construct air-tight “mud tubes” that protrude from the ground and lead directly to the surface of infested wood. In many infestation cases, these mud tubes are clearly visible on exterior foundation walls where they penetrate narrow cracks and connect to an interior structural wood item. However, subterranean termites may also construct mud tubes within hollow-block masonry foundations where they cannot be seen. When subterranean termite workers take this route to interior structural wood, resulting infestations typically last longer than usual and result in significant damage.

In order to prevent subterranean termite workers from accessing structural wood through the open space in hollow-block foundations, metal barrier shields are installed during construction in some cases. Metal shield barriers can also be added to existing structures for subterranean termite control purposes. Metal barrier shields are not used often today, as they have been overshadowed by the popularity of termiticide barrier systems. In addition to shields, “masonry caps” will prevent subterranean termite activity in hollow-block foundation walls. This method involves filling the void in hollow-block walls with concrete, which pest control professionals agree is the most effective method of preventing subterranean termites from exploiting hollow-block masonry homes.

Is your home built on hollow-block masonry? If so, have you had masonry caps installed?

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