Termites cause an estimated $5 billion in damage to more than 600,000 U.S. homes every year, and the threat is spreading. Climate change is pushing colonies into regions that were once too cold or too dry, while established infestations stay hidden for years inside framing and behind drywall. For builders and homeowners alike, catching a termite infestation in buildings early is the difference between a small repair and a structural bill. This article covers the statistics behind the rising threat, how termite colonies feed and spread, the warning signs to watch for, and the treatment and prevention strategies that keep wood structures sound for decades.
Protection has improved along with the threat. Pressure-treated lumber has been the standard for outdoor construction since the 1970s, and modern treatment chemistry, bait systems, and inspection practices give property owners more options than ever. The sections below lay out what is changing, what to look for, and how to assemble a protection plan that covers every gap.
Why Treated Wood Became the Default for Outdoor Construction
In the early 1970s, a test market in suburban Chicago introduced homeowners to pressure-treated lumber for building their own decks. The experiment worked, and the outdoor living market grew from it: decks, retaining walls, garden furniture, and raised bed gardens became standard weekend projects for DIYers and steady work for contractors. Decades later, treated wood is still the first choice of contractors and builders for these projects.
The Appeal of Real Wood With Built-In Protection
Contractors favor treated wood because it keeps the natural beauty and workability of lumber while resisting the organisms that destroy unprotected wood. Without protection, wood falls prey to termites, mold, and fungal decay within a few years of ground contact. The protection carries onto the jobsite as well: while crews build decks, replace framing, or renovate interiors, finished floors and surfaces stay covered with heavy-duty temporary floor protection so the new wood work is not scratched or stained before the customer moves in.
That attention to the work in progress is part of why treated-wood projects hold up: the material is protected from the day it arrives until long after the crew leaves. Decks, retaining walls, and raised beds built with treated lumber routinely outlast untreated structures by a wide margin, which is why builders specify it for anything that touches soil or weather.
Termite Biology: How Colonies Infest and Feed
Termites have been eating wood for more than 100 million years, and they occupy every landmass on Earth except Antarctica. Colonies range from a few hundred individuals to several million, and the queens of some species hold the longest lifespan of any insect: 30 to 50 years of near-continuous egg production. That combination of size and longevity means a single colony can gnaw at a building for decades.
Subterranean Termites Are the Most Common Threat
The subterranean termite is the species most often found in buildings. A large colony consumes about a pound of wood per day, which sounds modest until the damage accumulates across months or years. The insects stay hidden in soil and inside framing, so by the time a homeowner notices hollow-sounding studs or buckling paint, the damage is already extensive. Understanding how colonies operate is the first step in effective termite protection, and it shapes every treatment decision covered later in this article.
How Colonies Enter a Building
Subterranean termites build mud tubes over concrete foundations and through cracks in slabs to reach wood above the soil line. They need surprisingly little room: a gap the width of a credit card is enough. They also travel through plumbing chases, expansion joints, and anywhere wood touches soil, which is why inspections start at the points where the structure meets the ground.
Each colony sends out winged reproductives, called swarmers, once a year to start new colonies. A sudden cluster of flying insects near a window or a pile of discarded wings on a sill is often the first sign that a colony has been living in the structure for years. Days, weeks, or even months can pass while the insects eat away at a deck or a home, and severe damage may already be present by the time they are discovered.
Termite Damage by the Numbers
The scale of the problem is easier to grasp with figures. The U.S. Department of Agriculture estimates that termites damage more than 600,000 homes per year and cause about $5 billion in damage and repairs across the country. Standard homeowners insurance policies exclude termite damage, so most of that bill lands directly on the property owner.
The number of invasive termite species that destroy wood used in infrastructure climbed from 17 in 1969 to 28 in 2017, according to research published in the journal Ecology and Evolution. Climate change is expected to push the count higher, and the same code framework that governs fire protection engineering in buildings increasingly shapes termite protection requirements in regions where the risk used to be low.
Warmer, Wetter Conditions Expand Termite Range
Climate projections for North America call for higher average temperatures and more precipitation across most of the continent over the next century, with the largest changes in northern latitudes. Warm, damp conditions are exactly what termite colonies need to spread, so regions where termites were once a passing concern are becoming places where protection is required.
What the Shift Means for Builders
For builders, the practical effect is that termite protection is moving from a regional consideration to a national one. Specifying treated lumber, physical barriers, and soil treatments in areas that never needed them before is becoming standard practice, and it adds little to the cost of a project when planned at the design stage.
Detecting an Infestation Before It Spreads
Early detection is the cheapest form of termite control. A professional inspection once a year is the baseline, and homeowners can do their own walk-through between visits. The combination of detection methods, treatment options, and prevention strategies described here works only when the first step, finding the colony, happens on time.
Signs to Look For
- Mud tubes on foundation walls, floor joists, or sill plates
- Discarded wings near windows, doors, or light fixtures after swarming season
- Frass, the fine sawdust-like droppings of drywood termites, piled below infested wood
- Hollow-sounding wood when tapped with a screwdriver handle
- Buckling paint, sagging floors, or doors that no longer close properly
Where to Check First
The highest-risk areas are the points where wood meets soil: sill plates, porch steps, deck posts, and fence lines. Crawlspaces and attics deserve the same attention, along with any area with a history of moisture problems, because damp wood draws colonies in. A flashlight and a flat screwdriver are enough for a basic monthly check.
Treatment Options and Prevention Strategies
Treatment falls into two broad categories: eliminating an existing colony and keeping new ones out. Most professional programs combine both, and the table below compares the main methods available today.
Comparing Treatment Methods
| Method | How It Works | Best For | Key Limitation |
|---|---|---|---|
| Liquid soil termiticides | Chemical barrier applied to soil around and beneath the foundation | Whole-house protection against subterranean termites | Needs professional application and re-treatment over time |
| Bait stations | Stations buried in soil lure workers to a slow-acting toxicant that spreads through the colony | Long-term colony elimination with low chemical volume | Takes weeks or months to wipe out a colony |
| Borate wood treatments | Preservative soaks into wood and makes it toxic to termites | Treating framing and exposed wood in place | Ineffective once wood is buried or heavily weathered |
| Pressure-treated lumber | Preservative forced deep into the wood at the mill | New decks, fences, and structural lumber | Must be specified at purchase, not a retrofit option |
Inspectors and applicators work in crawlspaces, attics, and tight foundation areas, so the same safety goggles and hearing protection used on any construction site apply, along with respirators where chemical application or heavy dust is involved. Most treatment contracts include a re-inspection schedule, and the best ones guarantee the work between visits.
Prevention Practices That Last
Prevention is mostly about denying termites food, moisture, and access. The practices below cover the highest-impact items:
- Keep soil grades sloping away from the foundation so water never pools against the wall
- Maintain a visible gap between soil and wood siding, ideally 6 inches or more
- Replace wood-to-ground contact points such as fence posts with ground-contact rated treated lumber
- Store firewood and scrap lumber away from the house and off the ground
- Fix leaky pipes, gutters, and downspouts that keep wood damp
- Seal cracks in the foundation slab and around utility penetrations
Building a Termite Protection Plan That Lasts
A durable plan layers several defenses so no single failure is fatal. The same logic that drives fire protection in high-rise buildings, where redundant systems back each other up, applies to termite defense: treated wood, soil barriers, moisture control, and annual inspections each cover what the others miss.
A Year-Round Schedule
- Spring: book the annual professional inspection before swarming season peaks
- Spring: check mud tubes and moisture problems after the wet season
- Summer: inspect decks, porches, and fence lines for wood-to-soil contact
- Fall: clear gutters and re-grade soil away from the foundation before winter rains
- Winter: check crawlspace ventilation and humidity in heated homes
Keep a written record of inspections, treatments, and repairs. When a home changes hands, that history is the first thing a buyer’s inspector asks for, and it is the fastest way to prove the structure has been protected continuously. Prevention costs a few hundred dollars a year; replacing a load-bearing beam or a section of floor runs into the thousands.
The rising termite threat is real, but it is manageable. A combination of treated wood, smart site details, and a regular inspection habit keeps the most destructive insect on the planet out of the buildings people live in, and the protection only gets better as treatment chemistry improves.