Seven warning signs that termite damage has moved past cosmetic and into the beams, joists, and sills that hold your home up, and what each sign usually means.
Plenty of termite damage is cosmetic: surface trim, a window casing, a stretch of baseboard. What matters for the safety and value of your home is when the damage reaches the framing that carries load, the beams, joists, sill plates, and studs. In Berks County the culprit is almost always the Eastern subterranean termite, which lives in the soil and enters the house from below, so structural damage tends to start low (sills, basement and crawl space framing) and work its way along the wood. These seven signs usually mean it has reached something that matters.
Tap along a basement beam, a sill plate, or a run of trim with the handle of a screwdriver. Sound wood gives a solid, dull knock. Wood that subterranean termites have worked through often sounds hollow or papery, because the colony eats the softer inner wood along the grain and leaves a thin outer shell. A hollow sound on trim is a nuisance. A hollow sound on a carrying beam is a structural question.
When joists or the beam under them lose strength, the floor above starts to deflect. You may notice a dip toward the middle of a room, a bounce when someone walks past, or a soft spot near an exterior wall where the joist ends rest on a damaged sill. Floors in old houses are rarely perfectly flat, so the clue is change: a floor that feels different than it did a year ago.
Subterranean termites need moisture and build pencil-width tunnels of soil and debris to travel between the ground and the wood they feed on. You will usually find them on basement walls, crawl space piers, and the face of the foundation where it meets the sill. A tube is direct evidence of termite access. Break a small section open: active tubes are often rebuilt within days, which tells you the colony is still working.
As the framing under a wall settles unevenly, door and window openings go out of square. Doors start rubbing the head jamb or refuse to latch, and windows bind in their tracks. Humidity causes some seasonal sticking in Pennsylvania homes, so pay attention to openings that stick year-round or that stick on one side of the house more than the other.
Termite damage near the surface can push paint and thin wood outward, leaving blistering or rippling that is often mistaken for water damage. The two frequently show up together, because subterranean termites favor damp wood. If you find damage that looks like water damage but there is no obvious leak above it, consider termites as a cause.
The sill plate is the wood that sits directly on top of the foundation and carries the house frame. When termites eat into it, the frame can settle down onto a crushed or hollow sill, opening gaps at the top of the foundation, separating trim from the wall, or creating cracks in plaster near the floor line on exterior walls. This sign almost always points to sill plate damage, which is structural by definition.
Press the tip of a screwdriver into suspect wood with firm hand pressure. Sound framing resists; damaged framing gives, flakes, or lets the tip sink in. Often you will see layered galleries running with the grain, sometimes lined with soil. This is the most direct check a homeowner can make, and it is what a structural assessment does systematically along the full length of each member.
Any one of these is reason for a closer look. Two or more together, especially near the foundation, usually means the damage has reached structural wood. First, have a licensed pest control company confirm whether termites are active and treat if they are. Then get an assessment that probes the framing to find out how far the damage actually runs, because what is visible is almost always less than what is there. If an inspection report has already flagged damage, our guide on reading a termite inspection report explains what that finding does and does not tell you.
Treatment stops the colony, but it does nothing for wood that has already been hollowed out. Once you know the structure is involved, the fix is a structural repair: rebuilding the weakened wood back to code so the home is sound again. For a closer look at telling the difference, see how to tell if termite damage is structural.
Winged termites swarming indoors, most often in spring, usually mean a mature colony is nearby and has access to the house. They do not tell you how much damage exists. Call a pest control company to confirm and treat, then have the framing assessed.
Yes. Treated or abandoned damage does not regain strength. If the damaged wood carries load, it can keep deflecting and should be assessed and repaired.
No. Undersized joists, settled supports, rot, and past remodeling cuts can all cause sagging. An assessment from below identifies the actual cause before anyone decides on a repair.
Start in the basement or crawl space, along the top of the foundation and the sill plate, around any posts or piers, and near plumbing penetrations and the bottoms of basement stairs. These are the low, damp spots subterranean termites reach first.
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