Why Slab Cracks Let Pests Into Georgetown Homes

When the Ground Pulls Away From the Slab

Walk the edge of a Georgetown slab in August and you can often find a spot where the ground has pulled back far enough to fit a hand into the gap. That is not foundation failure on its own — it is the clay drying out and shrinking away from the concrete, and to some degree it happens every summer on both sides of I-35. The width changes with the weather: it opens in a dry stretch and can close again once rain soaks back in. What it opens, though, is a doorway. Ants, scorpions and termites all use that seam to reach the slab edge and the framing above it, which is why this crack matters more than its size suggests.

The gap behaves differently depending on which side of the highway a house sits on. East of I-35, in the Blackland Prairie clay under Berry Creek, Georgetown Village and Teravista, the soil swells hard when wet and shrinks hard when dry, so the crack there can open wide and close again within the same season. West of I-35, over the Edwards limestone and thin caliche around Sun City and Cimarron Hills, the surface moves less but the rock underneath is full of fractures that carry water sideways, so a gap there can stay open through spells when the east side has already closed back up.

This page covers why the gap opens, how to tell an ordinary shrinkage crack from one that signals real settlement, what a pest treatment along a slab edge is actually doing when it goes down, and why a house treated a few years ago in a wetter stretch is sometimes calling again now that the ground has dried out. It does not cover a lender's termite report, which is its own subject, and it does not cover foundation repair, which is a different trade from pest control even though the two problems can look alike from the yard.

The Gap as an Entry Point

Clay soil is made of fine particles that hold water between them the way a stack of wet sponges does. Soak it and the particles swell apart, pushing outward against anything in their way, including a slab edge. Dry it out and the same particles shrink back down, pulling away from whatever they were pressed against. A concrete slab does not move nearly as much as the ground beside it, so the gap opens along the edge of the slab rather than through the middle of it, and it usually shows up first on whichever side of the house gets the most afternoon sun.

Georgetown's summers are dry enough, often enough, that this cycle repeats every year rather than showing up once and staying. A run of a few weeks with no real rain is enough to open a visible gap along a slab on the Blackland Prairie side of town, and a longer drought pulls it wider and deeper. The ground does not need to be cracked everywhere for this to matter — one open run along a single wall, especially a south or west face that bakes all afternoon, is enough for something to get underneath the slab.

• A shrinkage crack runs vertical and even, following the clay's pull away from the slab edge
• A settlement crack runs diagonal from a corner, often widest at one end, and needs a foundation contractor
• Shrinkage gaps open widest in late summer after weeks without rain east of I-35
• Settlement cracks keep growing across seasons instead of closing back up when rain returns
• Doors and windows sticking alongside a crack points toward settlement, not simple shrinkage
• A crack narrower than a pencil that closes after rain is almost always shrinkage

Reading a Crack Correctly

Fire ants are the fastest to take advantage of an open gap. A colony sitting in a Georgetown yard will move part of itself into the seam within a day or two of the ground drying out, because the space under the slab edge stays cooler and holds moisture longer than the open lawn does. Striped bark scorpions use the same seam for a different reason — they are thin enough to fit through it easily, and they are hunting the moisture and the insects that gather wherever a house holds dampness against dry ground, which in a drought year is exactly at that slab edge.

Native subterranean termites take longer to find a gap but do more with it once they do. They build mud tubes up through the crack to reach the wood framing above the slab, and because the colony lives in the soil and follows moisture, a wide-open shrinkage gap can pull them toward a house that had no activity the year before. This is also why drought years are worse for termites here rather than better — the colony is chasing water, and in a dry Georgetown summer the moisture under a slab is often the closest source around.

• A liquid barrier along the slab edge blocks the gap ants and scorpions use to enter
• Treatment reaches down into the crack itself, not just the visible surface of the soil
• A repeat visit is often needed once a long drought breaks and the clay resettles
• Termite-specific treatment around a slab edge is a separate, deeper application than the general barrier

Shrinkage Crack or Settlement Crack

A shrinkage gap runs along the outside edge of the slab, between the concrete and the soil, and it is roughly the same width along most of its length. It opens in dry weather and narrows or closes once rain returns, and the slab itself stays level — a straight board or a level set across the floor inside will not show a dip. This is the ordinary, seasonal kind of crack, and it is the one a pest treatment is meant to address, not a sign that the house is moving.

A settlement crack is a different problem with different signs: a crack running through the slab itself or up a brick veneer rather than around the outside of it, doors or windows that stick or no longer latch the way they used to, or a visible slope when a level is set on the floor. That kind does not open and close with the weather the way a shrinkage gap does, and it is not something a pest treatment fixes — it calls for someone who works on foundations, not on the pests that get in through them.

Treating the Edge, and Doing It Again

A gap that opens along a slab edge in a Georgetown drought doesn't close on its own once rain returns; the clay swells back part way, but the space where ants, scorpions and termites got in the first time is often the space where they keep coming back through. Treating around a slab edge means placing a barrier in the soil right against the foundation, in the narrow band a pest actually crosses to get inside — not a general yard spray. On the Blackland Prairie clay east of I-35, where the cracking runs deepest, that barrier gets disturbed every time the ground shrinks and swells again, so a treatment that held through one summer can need repeating once a longer or harder drought opens the gap wider than before.

How long it holds depends on what happens to the gap afterward. A treatment put down while a Georgetown summer is still dry can perform well for months, but once real rain comes and the clay swells back against the slab, the barrier zone the pros worked into is disturbed along with the soil around it. That is not a failure of the work — it is the ground moving underneath something that was built to last through a season, not to survive being pulled open and squeezed shut again.

Why the Gap Comes Back After a Drought Breaks

Georgetown's dry-wet cycle is exactly what undoes a slab-edge treatment over time. The clay under Berry Creek and Teravista swells when a drought finally breaks, closing the gap the barrier was placed in and moving the soil around it; when the next dry stretch opens the gap again, it is opening into ground the original treatment no longer fully covers. A house treated once during a dry year and never since is often unprotected the next time the ground dries out, even though nothing about the house itself has changed in between.

This is why a slab gap is worth checking after any real drought, not just once. It costs little to walk the foundation of a house near Sun City or Water Oak after a dry summer and see whether the gap has opened again, and it is a cheaper conversation to have before scorpions or ants have already found their way in than after. The same logic holds on the east side of town, where the clay under Katy Crossing and Georgetown Village moves through the widest swing of any soil around Georgetown.