Signs of Termite Damage in Bay Area Homes: A Visual Identification Guide

Why Bay Area Homes Are Prime Targets for Termites

The Bay Area’s moderate temperatures and seasonal moisture create ideal conditions for termites. Unlike regions with harsh winters that push termites into dormancy, our climate allows colonies to remain active throughout the year. Subterranean termites thrive in the moist soils common across the South Bay, Peninsula, and East Bay foothills. Drywood termites, which need no ground contact at all, flourish in the warm attics and wall voids of homes from San Jose to San Francisco.

Older homes built before the 1980s are especially vulnerable. Many were framed with untreated lumber and lack the physical and chemical barriers that modern building codes require. But newer homes are not immune. Any wood-frame structure in the Bay Area is a potential target.

The difference between a $2,000 repair and a $50,000 structural restoration often comes down to timing. Homeowners who know what to look for catch infestations early. Those who do not may discover damage only during a remodel, a real estate transaction, or when a floor starts to sag.

Here are the seven most reliable signs of termite damage in Bay Area homes.

1. Frass: The Calling Card of Drywood Termites

Frass is the number one indicator of a drywood termite infestation. These tiny pellets are termite fecal matter, and drywood termites are meticulous about keeping their galleries clean. They carve small “kick-out holes” in the wood and push the frass out, where it accumulates in small piles below.

What Frass Looks Like

Drywood termite frass is remarkably uniform. Each pellet is hexagonal (six-sided) when viewed under magnification, roughly the size of a grain of sand, and wood-colored. Depending on what the termites are eating, frass can range from light tan to dark brown, sometimes even reddish. If a colony is feeding on multiple wood species, you may see mixed colors in one pile.

Frass is easy to confuse with sawdust at a glance, but the texture is different. Sawdust is irregular and fibrous. Termite frass is smooth, granular, and almost looks like coarse ground pepper or sand.

Where to Look for Frass

Check these locations regularly:

• Windowsills and door frames. Drywood termites frequently infest the wood around windows and exterior doors.
• Along baseboards. Frass accumulates at the base of walls where termites have infested the framing behind drywall.
• Below furniture. Headboards, bookshelves, and other furniture pushed against walls can hide kick-out holes. Pull furniture away from walls periodically to inspect.
• Attic spaces. Drywood termites love attic framing. Look for frass on top of insulation, along rafters, and near any stored items.
• Garage framing. Exposed wood framing in garages makes both frass and kick-out holes easier to spot.

If you sweep up a pile of frass and it reappears within a few days, you have an active colony. That is your signal to call a licensed pest inspector.

2. Mud Tubes: The Highway System of Subterranean Termites

Subterranean termites cannot survive exposure to open air. Their bodies dry out rapidly without moisture. To travel between their underground colony and the wood above ground, they construct mud tubes: enclosed tunnels made from a mixture of soil, saliva, and fecal matter.

What Mud Tubes Look Like

Mud tubes are roughly the width of a pencil, though they can be thinner or wider depending on the colony size and how long the tube has been in use. They are brown or dark tan, with an irregular, slightly bumpy texture. When fresh and active, they feel slightly damp. Old, abandoned tubes are dry and brittle, crumbling easily when touched.

Where to Find Mud Tubes

The most common locations include:

• Exterior foundation walls. Walk the perimeter of your home and look along the concrete foundation between the soil line and the first course of wood framing. Tubes often appear at the junction where concrete meets wood.
• Inside the crawl space. If your home has a raised foundation, the crawl space is the most likely place to find mud tubes. Check along the interior face of the stem wall, on pier blocks, on plumbing pipes, and on any wood posts or supports.
• Garage walls. The interior of attached garages, especially along the slab edge where the concrete floor meets the framing, is a common entry point.
• Around plumbing penetrations. Anywhere a pipe enters the home through the foundation or slab creates a gap that subterranean termites exploit.
• Expansion joints. Cracks in concrete slabs, expansion joints, and gaps around utility conduits all provide access.

The Break Test

If you find a mud tube and want to know if it is active, break a small section in the middle. Check back in a few days. If the tube is repaired, the colony is active. If it remains broken, the tube may be abandoned, but that does not mean the colony is gone. They may have found an alternative route.

3. Hollow-Sounding Wood

Termites eat wood from the inside out. They consume the soft interior cellulose while leaving a thin outer shell intact, which is why damage can go undetected for years. The wood looks normal on the surface, but behind that shell, the interior is hollowed into a maze of tunnels and galleries.

How to Test for Hollow Wood

Tap along exposed wood surfaces with the handle of a screwdriver or a small hammer. Sound wood produces a solid, resonant tone. Damaged wood sounds hollow, papery, or dull. You can often feel the difference too: pressing on severely damaged wood may cause it to flex or give slightly under finger pressure.

Pay attention to these areas:

• Door frames and window frames. These are frequently the first wood members attacked by both drywood and subterranean termites.
• Baseboards and trim. Run your knuckles along baseboards. A change in sound from one section to another often indicates localized feeding.
• Deck posts and porch framing. Exterior wood in contact with or near the ground is especially vulnerable to subterranean termites.
• Garage framing. Tap along the bottom plate (the horizontal piece of wood at the base of framed walls) in your garage. This is one of the most common places for subterranean termites to enter a home.

Probing with a Screwdriver

If tapping reveals a suspicious area, push the tip of a flathead screwdriver into the wood. Sound wood resists penetration. Damaged wood crumbles, flakes, or the screwdriver slides in with little resistance. You may also see the layered galleries left behind by termite feeding.

4. Sagging or Uneven Floors

When termites attack floor joists, subfloor sheathing, or sill plates, the structural members that support your floors lose their load-bearing capacity. Over time, this manifests as visible floor problems.

What to Watch For

• Soft spots. Areas of the floor that feel bouncy, spongy, or dip under your weight may indicate compromised joists or subfloor beneath.
• Visible sagging. Stand at one end of a hallway or room and look across the floor at eye level. A floor that dips in the middle or slopes toward one side may have structural damage.
• Buckling laminate or tile. Termite damage to the subfloor causes the surface above to buckle, crack (for tile), or develop gaps.
• Squeaking that was not there before. New creaks and squeaks can indicate that floor joists have lost material and are flexing more than they should.

If your floors feel different than they used to, do not assume it is simply the house settling. Especially in homes over 20 years old, a pest inspection should be part of the investigation.

5. Doors and Windows That Suddenly Stick

Many homeowners dismiss sticking doors and windows as seasonal wood expansion from humidity changes. In the Bay Area, where humidity fluctuations are relatively mild compared to other parts of the country, a door or window that suddenly becomes difficult to open or close deserves a closer look.

Why Termites Cause Sticking

Termite feeding distorts the wood framing around doors and windows. As structural members lose material, they can warp, twist, or sag slightly. This changes the geometry of the door or window opening, throwing it out of square. A door that hung perfectly for a decade and now scrapes the frame, or a window that used to slide freely and now jams, could be signaling termite damage in the surrounding framing.

How to Investigate

Look at the door or window frame closely. Check for:

• Hairline cracks in drywall or plaster radiating from the corners of the frame
• Gaps appearing between the frame and the wall
• Visible distortion (one side of the frame is no longer plumb)
• Frass or kick-out holes on or near the frame
• Any discoloration or bubbling paint on the frame itself

If the sticking is isolated to one door or window and other explanations (foundation settlement, recent moisture exposure) do not apply, termite activity is a real possibility.

6. Bubbling, Peeling, or Discolored Paint

When termites feed inside wall framing and approach the surface, they produce moisture as a byproduct of digestion. This moisture migrates through the remaining thin shell of wood and into the adjacent drywall and paint layers. The result looks very similar to water damage: bubbling paint, peeling, or discolored patches on walls and ceilings.

How to Distinguish Termite-Related Paint Damage

The challenge is that bubbling paint can have many causes, including actual water leaks, condensation, or poor paint adhesion. A few clues point toward termites specifically:

• No obvious water source. If the bubbling is on an interior wall with no plumbing, away from any windows, and with no roof leak above, termites should be considered.
• Frass nearby. Check the base of the wall below the affected area for any granular material.
• The wall sounds hollow. Tap the area. If it sounds notably different from surrounding sections, the framing behind may be compromised.
• Small pin holes. Drywood termites sometimes create kick-out holes that appear as tiny pinholes in the paint or drywall surface.

In the Bay Area, where many homes are 40 to 80 years old, paint anomalies warrant investigation rather than a fresh coat of paint over the problem.

7. Discarded Wings Near Windows and Light Fixtures

Termite swarmers (called alates) are the reproductive members of a mature colony. When conditions are right, they emerge in large numbers, fly a short distance, shed their wings, and pair off to establish new colonies. A termite swarm inside your home is one of the most definitive signs of an active infestation.

Identifying Discarded Wings

After a swarm, you will find piles of small, translucent wings near windows, sliding glass doors, light fixtures, and other areas where the swarmers are drawn to light. Termite wings are all roughly the same size (both front and back wings are nearly identical in length), which distinguishes them from flying ant wings, where the front pair is noticeably larger than the back pair.

Bay Area Swarming Seasons

Different species swarm at different times:

• Subterranean termites typically swarm in the Bay Area between January and April, usually on a warm day following rain.
• Drywood termites swarm between September and November, often during warm, still evenings.
• Dampwood termites (less common in residential structures but present in the Bay Area) swarm during summer months.

If you find discarded wings, save a sample in a plastic bag or jar. A pest control inspector can identify the species from the wings alone, which determines the treatment approach.

Bay Area Species: What You Are Dealing With

Understanding which termite species is present affects both the inspection strategy and the repair approach.

Drywood Termites (Incisitermes minor)

Drywood termites are the most common structural pest in Bay Area homes. They live entirely inside the wood they consume and do not require contact with soil or an external moisture source. Colonies are relatively small (a few thousand individuals) but a single home can harbor multiple colonies simultaneously.

Signs specific to drywood termites:

• Frass pellets (hexagonal, wood-colored)
• Kick-out holes (tiny, clean-edged holes in wood surfaces)
• Swarming in fall (September through November)
• Damage tends to concentrate in attic framing, window and door frames, and hardwood trim

Subterranean Termites (Reticulitermes hesperus)

The western subterranean termite is the second most common species in the Bay Area and causes more damage per colony than drywood termites because their colonies are much larger, often exceeding 60,000 workers. They live underground and require constant moisture.

Signs specific to subterranean termites:

• Mud tubes on foundations, walls, and pipes
• Damage concentrated near ground level (sill plates, bottom plates, subfloor)
• Swarming in late winter and spring (January through April)
• Wood damage follows the grain and has a layered, almost cardboard-like appearance

Dampwood Termites (Zootermopsis angusticollis)

Dampwood termites are less common in well-maintained homes because they require very high moisture content in the wood they infest. They are found in areas with water leaks, poor drainage, or wood-to-soil contact. Their presence almost always indicates a moisture problem that needs to be solved alongside the termite treatment.

Signs specific to dampwood termites:

• Larger frass pellets than drywood species
• Damage in areas with moisture problems (leaking pipes, poor drainage, decayed wood)
• No mud tubes (they live directly in the wood like drywood termites)
• Swarming in summer months

When to Call a Professional

If you spot any of the signs described above, do not wait. Termite damage only gets worse and more expensive over time. Here is the recommended course of action:

1. Contact a licensed pest control company for a formal inspection. In California, only licensed pest operators can issue Wood Destroying Organism (WDO) reports. Many companies offer free inspections.

2. Get the termite report. The inspector will document all findings and categorize them as Section 1 (active infestation or damage requiring immediate attention) and Section 2 (conditions likely to lead to future infestation).

3. Have the pest company handle treatment. Depending on the species and extent, this may involve localized treatment, fumigation (tenting), or a combination.

4. Bring in a licensed contractor for structural repairs. Once the pest company clears the infestation, a general contractor assesses and repairs all structural damage. This is the step where Custom Home comes in. We receive the termite report, inspect the flagged areas plus adjacent structures for hidden damage, and provide a clear repair scope.

The pest company handles the bugs. We handle the building. That separation of expertise ensures both sides of the problem are addressed properly.

Protecting Your Home Going Forward

After treatment and repair, ongoing prevention reduces the risk of reinfestation:

• Schedule annual pest inspections. Professional eyes catch what homeowners miss.
• Eliminate wood-to-soil contact. Ensure siding, framing, and fence posts are at least 6 inches above grade.
• Fix moisture problems. Repair leaky faucets, improve crawl space ventilation, and ensure downspouts direct water away from the foundation.
• Monitor for frass and mud tubes. A quick visual check of your garage, crawl space access, and foundation perimeter twice a year takes 15 minutes and can save thousands.
• Keep firewood away from the house. Store firewood at least 20 feet from your home and off the ground.

Bay Area homes are valuable assets. Knowing the signs of termite damage and acting on them quickly protects both your investment and your family’s safety.