Subterraneans that find the gap between the floor slab and wall encounter the bottom of a tasty wood baseboard, and also the thin vertical strips that run up the wall from the floor to the ceiling behind the drywall, called furring strips. After they munch on the baseboard a while, the furring strips provide a highway directly up to the wood roof trusses at the top of the wall. And, best of all for the little critters, they can do all their damage undetected.
The photo above shows a fiber expansion between a floor slab and concrete block stem wall. Newer homes combine the floor slab and concrete footing into one piece, called a “thickened edge slab” or “monolithic foundation.” The concrete block is laid along the perimeter of the slab, over the thickened edge, and there is no concealed gap in the ground. Termites can still find their way into the home thru penetrations in the floor slab created for plumbing pipes, electrical conduits, air conditioning refrigerant lines, and small cracks that develop in the slab as it hardens or settles. But access to the home’s wood components is not as easy as in a stem wall home.
Drywood termites have a different strategy: during the spring swarming season, a winged queen termite and her flying entourage enter the house from above, typically through a soffit vent or gap in the roof around a chimney or plumbing vent. They are slower to establish a colony than subterraneans and less voracious eaters but can be harder to detect because they don’t leave the telltale surface mud-tubes that are characteristic of subterraneans. Whether it’s subterraneans or dry wood, concrete block houses may be less vulnerable to termite attack than a frame house, but not immune.
Subterranean termite mud tube running across drywall on interior of
concrete block wall, from wood window trim to wood cove molding.