A perimeter application deals with the insects and rodents that are already coming and going. It does nothing about the reason they can. Exclusion is the other half of the job: finding the openings that let things in and closing them with materials that hold. It is slower, it happens once instead of quarterly, and on most houses it changes the baseline more than anything sprayed on the outside wall.
None of this is a substitute for treatment when an active population is inside. It is what determines how often that situation comes back.
Start with what the pest needs, not with the pest
The EPA frames household pest prevention around three needs, food, water and shelter, and gives homeowners three matching instructions: starve them out, dry them out, keep them out (US EPA, Do You Really Need to Use a Pesticide?). The first two are housekeeping and plumbing. The third is exclusion.
The starving list is specific. Seal boxes and bags of food, and store open items such as cereal, flour or sugar in containers, because as the EPA notes, roaches climb into cardboard with ease. Clean up spills and crumbs right away, wash dishes rather than leaving them, keep a tight lid on trash and empty it often, place trash cans away from a back door, and do not leave pet food out overnight.
The drying list matters more than people expect indoors. The EPA notes that although roaches can live up to a month without food, they can die within a week without water. It asks homeowners to drain standing dish water from a sink, wipe up spilled liquid as soon as it appears, fix or report leaking faucets, radiators, dishwashers and washing machines, and empty excess water from flower pots and plant stands.
How small an opening has to be
This is where most homeowners are wrong by a wide margin. Texas A&M AgriLife Extension puts numbers on it: “A roof rat can enter a home through a gap under a door as narrow as 1/2 inch, or a hole the size of a quarter,” and for squirrels, “A 1/2 inch gap is all that a squirrel needs to get into an attic” (Texas A&M AgriLife Extension, Insects in the City: Rodents in Attics).
Half an inch is not a hole anybody notices from the driveway. It is the daylight under a garage door that has settled, the gap where a soffit return meets brick, the space around a hose bib. Once you accept that number, the walk around the house becomes a different exercise.
The openings that matter most
AgriLife narrows it usefully: “For most homes the most likely entry points include gaps around the garage door, venting and flashing on the roof, and ground-level gaps under and around siding.” It also notes that attached garages are one of the main entry points for rodents in suburban homes, and that older houses with crawl spaces can have numerous openings underneath.
A workable inspection order, from the ground up:
- Garage door. Close it and look from inside with the light off. Any daylight along the bottom seal or at the corners is an opening, and the corners are the part that fails first.
- Doors into the house. Same test. Exterior doors, the door between garage and living space, and any door onto a patio.
- Ground level around siding. Where siding meets the slab or foundation, and every point where a pipe, hose bib, cable, gas line or condensate line passes through a wall.
- Utility and dryer vents. Missing or broken covers, and flap vents that no longer close.
- Roofline. Soffit and gable vent screens, flashing, and anywhere two roof planes meet a wall. Binoculars from the yard work for a first pass.
- Crawl space, if you have one. Access hatches, vent screens and the perimeter skirt.
Materials that actually hold
Rodents chew, so the material matters as much as the sealing. AgriLife’s list is short: “Holes and gaps can be filled with cement, low expansion-expanding foam (careful not to use too much) and brass or stainless steel wool.” The caution about foam is worth repeating, because expanding foam alone is a filler rather than a barrier and is easily chewed through. Metal wool packed into a gap, then sealed over, is the standard approach for that reason.
The same source notes that holes around pipes and soffits need a durable sealant, and that door sweeps, kick plates and doorsills should be maintained and repaired regularly rather than installed once and forgotten. Door hardware is a consumable on a Texas house, particularly on a west-facing door that takes a full summer of heat.
The indoor half
Exclusion inside a house is about limiting movement between wall voids and living space. The EPA’s list under keep them out is straightforward: seal cracks and openings along baseboards, behind sinks, and around pipes and windows; repair holes in door and window screens; check boxes and bags for roaches before bringing them inside; and clean up clutter, including stacks of newspapers, paper bags and cardboard boxes, which make good hiding places.
On trapping, the EPA advises setting traps to control rats and mice, and if baits are used, making sure they are in a tamper-resistant bait station made of durable plastic or metal, placed where children and pets cannot reach them. In a house with a dog or small children, that detail is not optional.
Why exclusion changes the economics of a plan
A treatment addresses a population. Exclusion addresses a supply line. If the supply line is open, the population is restored between visits and the service becomes maintenance of a symptom. If it is closed, the same treatment has a much better chance of finishing something.
This is also why a company worth working with will talk about your building. AgriLife describes exclusion as effective particularly as part of an integrated program that includes other control measures, and the reverse holds too: control measures work better on a building that is sealed. If nobody has mentioned your garage door or your soffit screens, the plan is only doing half the work.
Where exclusion does not finish the job
Some situations need more than sealing. An animal already inside a wall or attic has to be dealt with before the opening is closed, or you create a different problem. Structural damage, a roof that needs work before any screen will stay put, or a crawl space you cannot safely enter are all reasons to get someone else involved. Insects that fly, and insects that arrive on objects rather than through gaps, are also outside what exclusion can solve on its own.
For the pests where exclusion carries the most weight, our page on rodent activity in and around a home covers what an inspection looks at, and the overview of cockroach pressure in Texas homes explains why the moisture and clutter side matters as much as the sealing. If you are weighing what to take on yourself, our comparison of doing the work yourself versus hiring someone is the right starting point, and the guide to signs a problem has gone past the homeowner stage covers when sealing alone will not be enough.
If you do bring a company in, ask them to confirm license status and insurance coverage, ask whether exclusion work is included or quoted separately, and ask for the list of openings they found in writing. That list is useful to you whether or not you hire anyone. Homeowners in the Houston area deal with a heavy year-round pest load and a lot of older housing stock, and our Houston area page outlines how matching works there.
Checking what is available in your area
texaspestcontrolpro.com is a connection service. We do not perform pest control and we do not employ technicians. If you would like to be matched with participating providers based on your service area, you can use the request form on this page. Availability varies by area and by season, and you decide whether to move forward with anyone you speak to.
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