Termites and Structural Damage: Understanding the Hidden Threat

Termites threaten a building’s structure by hollowing out the wood that holds it up: wall framing, sill plates, roof trusses, floor joists, subfloors and the frames around doors and windows. Because they eat from the inside and leave the surface intact, a beam can look solid while most of it is gone, which is why termites are often called silent destroyers.

In South Florida the threat comes from two directions. Subterranean termites rise from the soil through cracks and joints in concrete, while drywood termites fly in and attack attics, trim and furniture from above. This guide explains which parts of a home are at risk, how each type reaches them, how to tell cosmetic damage from structural damage and what stops the damage before it gets that far.

Why Termite Damage Stays Hidden

Termites avoid light and dry air. Subterranean termites travel inside mud tubes and stay within the wood they eat; drywood termites spend their whole lives sealed inside it.

The way they eat wood makes the damage even harder to see. According to Virginia Tech’s extension service, subterranean termites often eat only the softer springwood, leaving the grain and outer surface intact, so damage can go unnoticed for a long time. UF/IFAS notes that Formosan termite galleries follow the wood grain and that termites often bring soil into them. Drywood termites, by contrast, cut galleries across the grain and leave a paper-thin surface layer over them.

FDACS sums up the result: termites do their damage behind closed walls and may feed for several years before anyone discovers them. UF/IFAS adds that subterranean termite damage is often first seen during remodeling.

Which Parts of a Home Termites Damage

Not all damage is equal. The table separates the structural members that carry loads from the finishes that do not.

FDACS notes that termites can also destroy paper products such as books and cardboard, which is why boxes stored against garage walls often show damage first. Our article on why garages often show termite problems first explains that pattern.

How Subterranean Termites Reach Wood in Concrete Homes

Many South Florida owners assume a concrete-block house on a slab is termite-proof. It is not. Subterranean termites cannot eat concrete, but they use every gap in it. Virginia Tech lists the usual routes:

• Slab cracks and expansion joints
• Utility conduits and plumbing connections that pass through the slab
• Places where wood touches soil
• Gaps behind stucco, brick veneer or other cladding that runs below grade

FDACS adds that large settlement cracks give subterranean termites access and that treating them properly may require lifting flooring and drilling around the crack. It also warns that foam board insulation in contact with soil gives termites a hidden entry point, and that sill plates close to the soil are vulnerable to both moisture and termites.

Moisture is the other half of the story. Virginia Tech notes that homes with flat roofs or chronic leaks are sometimes at risk of above-ground subterranean infestations, and that the moisture problems themselves may be as damaging as the termites. In Miami-Dade and Broward, both Formosan and Asian subterranean termites are established, and UF/IFAS warns that Asian subterranean termite damage can become severe in a relatively short time when a large, mature colony invades a building.

Carton Nests Inside Walls

Formosan and Asian subterranean termites build carton: a mix of soil, chewed wood, saliva and feces that they pack into wall voids and hollowed wood. UF/IFAS describes carton in hollowed wood or structural voids as a sign of an advanced Asian subterranean infestation. When a contractor opens a wall and finds it, the colony has usually been there a long time.

How Drywood Termites Damage a Home From Above

Drywood termites need no soil and no outside moisture; they get water from the wood itself. According to UF/IFAS, the West Indian drywood termite infests hardwoods and softwoods shielded from rain, including structural lumber and furniture, and prefers the softer sapwood.

That puts roof framing, attic sheathing, window and door frames, trim and wood furniture at risk. The giveaway is small, six-sided pellets pushed out of kick-out holes. Because each colony lives entirely within the wood, a house can have more than one separate colony at a time. Learn the full species profile on our Florida drywood termite page.

Trees, Storms and Structural Risk

Termite damage is not only inside the house. UF/IFAS reports that Formosan subterranean termites feed on the dead wood at the center of living trees and hollow them out. The tree may stay alive, but it is weakened structurally and more likely to collapse, especially in high winds. A hollow tree next to a roof is a real hazard during South Florida’s hurricane season, and UF/IFAS recommends inspecting trees near structures regularly.

Storms also create new risks: water intrusion, wet framing and debris piles all make conditions easier for termites. Our guide to termites after the storm covers what to check once the weather clears.

Cosmetic or Structural? How Damage Is Assessed

A termite inspection and a structural evaluation answer different questions. Florida’s official Wood-Destroying Organisms Inspection Report records live termites, evidence and visible damage, but it states plainly that it is not a structural damage report. It covers only visible and accessible areas, and it directs readers to qualified building trade experts to judge structural soundness.

Signs that damage may have gone beyond cosmetic:

• Floors that feel soft, bouncy or sag between walls
• Doors and windows that start to stick or no longer latch
• New cracks in drywall near door corners or ceilings
• Ceilings or roof lines that dip
• Wood that crumbles when probed with a screwdriver

A sensible order is: confirm the species, treat the colony, then have a licensed contractor or engineer evaluate and repair the structure. Repairing first can trap an active colony behind new drywall. Damage from moisture can look similar, so read water damage vs. termite damage if you are unsure which you have.

How to Stop Termites Before Damage Becomes Structural

Every month of hidden feeding adds to the repair bill, so the goal is to find termites while the damage is still in trim or a single board.

• Inspect every year. FDACS calls an annual termite inspection a must for older homes.
• Keep the foundation visible. Siding, stucco and foam insulation should stop 6 to 8 inches above grade, FDACS advises, so mud tubes can be seen.
• Control moisture. Repair leaking pipes and foundation cracks, direct sprinklers away from walls and install gutters with extensions.
• Have large slab cracks evaluated and sealed after any needed treatment.
• Break wood-to-soil contact at decks, fences, steps and trellises.
• Watch for early signs such as wings, mud tubes, pellets and blistered paint. Our guide to identifying and addressing early termite signs lists them all.

When termites are found, Toro’s termite control service starts with a free inspection to identify the species and check how far the damage goes. Subterranean termites are treated with the Sentricon baiting system around the property, with no drilling into the slab and no trenches. Localized drywood colonies can be treated with TORO-GUARD, a non-tenting treatment, while tent fumigation treats drywood termites spread through the structure, including walls, trim and furniture. Toro has protected South Florida buildings since 1969 and backs its work with the 110% Satisfaction Guarantee.

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Frequently Asked Questions

Educational content. This article is for general information about pests in South Florida and is not medical, legal or professional advice. If you have a bite, sting or allergic reaction, contact your doctor; in an emergency, call 911. Pest problems vary from home to home, so a licensed professional should inspect before treatment. When using any pesticide, always read and follow the product label.

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