A snake under a concrete slab is usually a harmless garter or rat snake that found a cool, dark, damp spot with a steady supply of rodents. It is not trying to bother you, but you still want it gone, and you want it to stay gone.
The honest truth is that most snakes under a slab are harmless, and the fix is more about sealing and starving them out than about fighting them. Here are nine ways to handle it, in rough order of what actually works.
- Find and seal the gaps around the slab first, or new snakes keep moving in.
- Remove rodents and moisture, because that is what the snake is there for.
- Use exclusion and traps to clear the snakes already under there.
- If you can’t identify the snake, assume it is venomous and call a pro.
First, find how they are getting under there
Snakes get under a slab through:
- Expansion gaps between the slab and foundation walls.
- Cracks in the concrete.
- Gaps around pipes and utility penetrations.
- Deteriorated mortar in brick or block foundations.
- Drainage pipes and weep holes.
A young snake can get through a gap a quarter inch wide, so even a small opening is an open door.
Nine ways to remove snakes under a slab
- Install a one-way exclusion door over the main entry point. The snake can leave but not get back in. Leave it in place for a couple of weeks.
- Remove the rodents. Snakes are there for the food. Get rid of the mice and rats under the slab and the snakes lose their reason to stay.
- Reduce the moisture. Fix leaks, improve drainage, and dry the area out. A dry, hot space is not a place snakes want to be.
- Seal every crack and gap. Use hydraulic cement for larger cracks, expanding foam around pipes, and hardware cloth over vents.
- Install a barrier. Bury hardware cloth around the slab perimeter so snakes can’t dig or slip back under.
- Use a live snake trap or trap tube placed along the walls where snakes travel. Check it often and release any non-venomous snake away from the house.
- Clear the area above and around the slab. Remove debris, wood piles, and tall grass so snakes have no cover.
- Try a repellent with realistic expectations. Most snake repellents, including sulfur, have little proven effect, and any effect fades after rain. Treat them as a minor supplement, not a fix.
- Call a professional. For a venomous snake or a recurring problem, a licensed wildlife control operator is the right call.
A word on glue traps: they do catch snakes, but they are inhumane and are restricted in some places, and they often catch other animals too. I would reach for a live trap or exclusion before a glue board, and check your local rules first.
Safety first
Never try to handle a snake you can’t identify. If it is venomous, or you are not sure, assume the worst and call a professional. Copperheads and rattlesnakes do end up under slabs in some regions.
Preventing them from coming back
- Seal every gap and crack around the slab.
- Keep the area clear of debris, wood piles, and tall grass.
- Install a barrier before spring, when snakes get active.
- Control the rodent population.
- Check the slab perimeter monthly for new gaps.
Frequently Asked Questions
Through expansion gaps, cracks in the concrete, openings around pipes, and weep holes. Even a quarter-inch gap is enough for a young snake, and older slabs with settled cracks are especially vulnerable.
No. Snakes can’t chew through or crack concrete. The slab itself is fine. The concern is that snakes can use gaps in the slab or foundation to get into your home, so sealing those gaps is what protects you.
Maybe, if the food runs out or the area gets too hot and dry. But if the slab stays cool, damp, and full of rodents, the snake may stay indefinitely. Active removal is usually the reliable answer.
Doing it yourself is cheap, just the cost of hydraulic cement, hardware cloth, and expanding foam. Hiring a pro costs more and depends on the size of the slab and how many entry points there are, so get a couple of quotes.
Usually not. The ones you find under a slab are typically harmless garter or rat snakes. But since you can’t be sure from a distance, treat any snake you can’t identify as potentially venomous and call a pro rather than poking at it.
The Bottom Line
Getting snakes out from under a slab is a sealing job first and a snake job second. Find the gaps, remove the food and moisture, and give the snakes a one-way exit. Then close everything up so they can’t come back.
If you can’t identify the snake or it keeps coming back, call a licensed wildlife control operator. The goal is a snake-free slab without anyone getting hurt.
