Termites and Houston houses: why a pest contract is not a building detail

A termite contract treats the soil around your house. It does nothing about how the house itself lets termites in, or how well it hides them once they are inside, and in Houston that second part decides most of the repair bills. The practical fixes are unglamorous: keep a visible band of slab between soil and anything made of wood, keep water away from the walls, and make sure every part of the house can be looked at by the person doing the annual inspection.

The usual advice runs the other way. Get a contract, renew it every year, and the pest company has it handled. That advice is not wrong so much as incomplete. A treatment is only as good as the house it is wrapped around, and a lot of Houston houses are built, remodeled or landscaped in ways that give termites a hidden route past it.

Which termites are actually a problem in Houston?

2 kinds matter for a house here.

The native subterranean termites live in the soil and come up into wood through mud tubes, thin tunnels of soil and saliva they build to stay moist. They are slow by termite standards, and a house that is inspected every year usually catches them early.

Formosan subterranean termites are the reason Gulf Coast pest companies talk differently from the rest of the country. They arrived in the region through port cities and are now established around Houston. Their colonies are far larger than native colonies, which means damage happens faster once they find a way in. They can also set up a colony above ground, with no soil contact at all, wherever a steady water source exists: a slow roof leak, a sweating AC line, a plumbing drip inside a wall. A soil treatment does nothing about a colony living in the second floor.

The swarms are how most owners first learn this. Formosans swarm on warm, humid evenings in late spring, and they fly toward lights. If you have ever seen a cloud of winged insects around a porch light in May, that is what it was. A swarm near the house is not proof of an infestation inside it, but it is a good week to book the inspection.

Drywood termites exist too, and they live entirely inside dry wood with no soil connection. They are a smaller share of the calls here than the subterranean kinds. They are treated differently, often by tenting the house, and none of the soil-side advice below applies to them.

Why do Houston houses give termites a way in?

Because of what they sit on and how they are built.

Most houses in the region built in the last few decades sit on a post-tension slab, because gumbo clay swells when it is wet and shrinks when it is dry, and a slab has to ride that movement. The movement is the problem. It cracks slabs, opens joints in brick veneer, and pulls sealant out of the gap where a pipe comes up through the concrete. Subterranean termites only need a crack about the thickness of a card. The piece on gumbo clay and Houston foundations covers the movement itself.

The weakest spots in a slab house are predictable.

• Plumbing penetrations. Every pipe that comes up through the slab is a gap in the concrete, and the gap is usually hidden inside a wall or a cabinet.
• The bath trap. Many slab houses have a boxed-out opening in the slab under the tub or shower, left so the drain could be connected. It is open soil under the house, directly beneath a wet room, behind an access panel most owners have never opened.
• Expansion and cold joints. Where 2 pours meet, or where the garage slab meets the house slab, there is a seam termites can follow.
• Brick veneer. The cavity behind brick is dark, protected and usually damp. Tubes built inside it cannot be seen from outside or in.

Pier-and-beam houses, common in the Heights, Woodland Heights, Norhill and parts of Montrose, have a different profile. Wood sits closer to the soil, and in older houses the skirting, steps and porch framing often touch the ground outright. The upside is that a crawlspace can be inspected. A termite tube on a pier is visible to anyone with a flashlight and the willingness to go under there, which is more than can be said for a tube inside a slab house's wall.

Does the usual advice to water the foundation make termites worse?

It can, and this is the real tension in Houston house care.

Watering the foundation perimeter in a dry summer is standard local advice, and it is good advice. Gumbo that dries out shrinks away from the slab, and a slab that loses support at the edges settles. Keeping the soil at a steady moisture level limits that.

Subterranean termites also want steady, moist soil right against the house. So the soaker hose, the irrigation head, the mulch bed and the downspout that dumps at the corner all make the perimeter more attractive.

You do not have to choose. Run the soaker hose a foot or so out from the slab rather than tight against it, so the soil stays moist without being soaked at the concrete line. Keep mulch pulled back from the wall. Aim irrigation heads away from the house. Move downspout discharge several feet out. And do not let flower beds creep up the face of the slab over the years, because a raised bed against the wall buries the one strip of concrete that lets an inspector see a tube coming up.

What should stay visible around the house?

The slab edge.

The single most useful termite detail on a slab house is a clear band of exposed concrete, around 6 inches, between the soil and anything wood, siding or stucco. With it, a mud tube coming up the outside of the slab is visible to anyone walking the perimeter. Without it, the tube goes straight from soil into the wall and nobody knows until the baseboard gives.

That band disappears over time. Landscapers add soil. Owners add beds. A patio gets poured up to the siding. A driveway gets extended flush with the brick. Walk around your house and look for any place where soil, mulch, pavers or a deck meet the wall directly. Each one is a place an inspector cannot see.

Foam insulation needs a specific mention. Rigid foam board on the outside of a slab edge, or foam siding systems run down to grade, give termites a soft, hidden path up through the material and into the wall, where no one will see the tubes. Codes in heavy-termite regions restrict foam in contact with the soil for this reason. On a new house or a major remodel, ask your designer how the slab edge is insulated and how it will be inspected. Spray foam inside the house carries a milder version of the same problem, because it can cover the sill and the bottom of the wall where a tube would otherwise show; the piece on spray-foaming an existing Houston attic covers where that foam goes and why.

What should be built into a new house or a big remodel?

This is where the architect and the pest company should be in the same conversation, and usually are not.

• A soil treatment or a bait system before the slab is poured. A pre-construction treatment is applied to the soil under the slab. The alternative is a bait system installed around the house afterward. Either is a decision for the builder and the pest company, but it should be on the drawings or in the specification, not left to whoever shows up.
• Treated wood where it belongs. Sill plates on a slab are pressure-treated as a matter of course. Borate treatment of the lower framing is an option some builders here use as a second layer.
• Sealed penetrations. Every pipe through the slab gets sealed, and the bath trap gets either a physical barrier or an access panel someone will actually open.
• A drainage plan that moves water away from the walls. Gutters and downspouts that discharge well clear of the house, and grading that falls away from it. Most of that is also flood and foundation work, which is why it tends to get done well or badly as a package.
• No foam, soil or wood at the slab edge. The visible band is a drawing detail. If it is not drawn, it usually does not get built.
• Access. On a pier-and-beam house, a crawlspace with enough height and an opening big enough for a person. On a slab house, removable panels at plumbing walls.

If you are comparing designers, how they draw the base of the wall is a fair question. Our piece on what is in an architect's drawing set describes the difference between a permit set and a set detailed enough to answer it.

Is a pier-and-beam house better or worse for termites?

Neither, exactly. The risks are different.

A pier-and-beam house puts wood closer to the soil and has more places where old framing, porches and steps meet the ground. In a 1920s Heights bungalow, the original skirting has often been replaced with wood that touches soil, and the porch has been rebuilt more than once by different people with different ideas. On the other hand, everything under the floor can be seen. An inspector can crawl the space, find the tube on a pier, and trace it.

A slab house hides its problem better. The entry points are inside walls, under tubs and behind brick, and damage is often found only when someone pulls a baseboard or opens a wall. If you are buying either kind, the question is less about which is safer and more about whether the house as it stands can be inspected. Modern Acre Studio's article on choosing between a slab and pier-and-beam for a Houston house sets out the wider tradeoffs for a new build.

What does a termite contract actually cover?

Less than many owners assume. Read the contract before you rely on it.

Most contracts are either a retreatment agreement, where the company comes back and treats again if termites return, or a repair agreement, where the company also pays for some damage. Repair agreements cost more and usually carry limits and exclusions. A common exclusion is damage in areas that could not be inspected. That brings you back to the slab edge and the bath trap.

Homeowners insurance usually does not cover termite damage at all, on the reasoning that it is a maintenance problem rather than a sudden event.

In Texas, pest control is licensed by the Texas Department of Agriculture. A company can be looked up, and it should be before you sign. That is a contrast with the general contractor who may be repairing the damage, because Texas does not license general contractors; the article on Texas general contractor licensing explains that gap and what to check instead.

What should I check when buying a Houston house?

Ask for a wood destroying insect inspection. In Texas it is a standard report, done by a licensed pest inspector, and many buyers get one alongside the general home inspection. It records visible evidence of termites and conditions that invite them.

Then read it for the second half, the conditions. A clean report on a house with soil against the brick, a buried slab edge and a closed-up bath trap tells you the inspector did not see termites. It does not tell you there are none. Ask whether there is an existing contract, whether it transfers to you, whether it is retreatment or repair, and whether the house has been treated before, and for what.

If you are buying a narrow-lot townhouse, the brick and stucco at the ground floor and the connection between the garage slab and the house slab are worth particular attention; the piece on buying a Houston 3-story townhouse goes floor by floor.

Where does this advice not apply?

A lot of Houston houses have never had termites and never will, and the owners should not spend money as though they are under siege. Steel framing, concrete block walls and whole-house barrier systems are sometimes sold to Houston buyers as termite solutions. For most houses they solve the wrong problem at a high price. A wood-framed house with a clear slab edge, dry walls, a working contract and an annual inspection is well protected.

The owners who should act are the ones with specific conditions: soil or mulch against the siding, a leak that has been dripping inside a wall for months, a pier-and-beam house with wood touching the ground, or a remodel that is about to open walls anyway. For those houses, the fixes are mostly cheap and the damage is not. If a remodel is on the table, whether to remodel or tear down and rebuild is the larger question, and the register of Houston architecture firms lists practices that do residential work if you want someone to draw the base of the wall properly.