Snakes in a Crawl Space or Under the House: What to Do

A snake under the house is a symptom, not the problem. It is there because the crawl space is cool, dark and undisturbed, and above all because something small and furry is living there too. Deal with the rodents and the gaps, and the snakes stop arriving.

Confirm it first

A surprising share of crawl-space snake reports are a shed skin left behind by an animal that moved on weeks earlier.

Real evidence, in order of reliability:

• A shed skin — proof a snake was there, not that it still is
• The snake itself, usually against a wall or on a pipe rather than in the open
• Scuff trails in undisturbed dust
• A musky smell, which some species release when disturbed

Not evidence: a hole in the yard (usually rodents or crayfish), rustling in insulation (usually mice), or a single sighting outside near the foundation.

Identify before you act

This is the only genuinely risky part of the job, and doing it from six feet away removes nearly all of the risk.

Getting it out

For a snake you have positively identified as harmless:

1. Open the exit — the crawl space hatch or garage door — on the side that gets sun, during the warm part of the day.
2. Clear a straight path to it. Move boxes, bins and anything that makes the route a maze.
3. Leave. Give it several hours with nobody moving around. This works far more often than people expect.
4. If it needs steering, use a snake hook or a long-handled rake from several feet away, and guide rather than lift. Never use your hands, a shovel, or anything that requires you to be close.
5. A large trash can tipped on its side with the snake steered in, then carried out and released at the treeline, is the standard method for a calm harmless snake.

Then remove the reason it came

Rodents first. A crawl space with mice is a stocked larder. Trap them, clear the nesting material, and move stored birdseed, pet food and grass seed into sealed metal or hard plastic bins.

Then the gaps. Work the foundation with a flashlight and close anything a quarter-inch or wider:

• Crawl space and foundation vents → quarter-inch galvanized hardware cloth, screwed down, not stapled
• Pipe and cable penetrations → expanding foam backed with hardware cloth, then sealant
• The access hatch → weatherstrip it so it closes flush
• Garage door → a proper door sweep; the gap under a warped garage door is the single most common entry in the whole house
• Foundation cracks → masonry sealant

The perimeter

Snakes cross open ground reluctantly. A clear, dry, short band around the foundation does more than anything sold in a bottle:

• Mow within a few feet of the wall and keep it short
• Move woodpiles, rock piles and compost well away from the house
• Clear leaf litter and dense groundcover against the wall
• Keep mulch shallow near the foundation — deep mulch holds the rodents
• Fix dripping taps and clear standing water

What does not work

One more time, on leaving them alone

A harmless rat snake or king snake under your house is eating the mice that got there first — king snakes will also take copperheads. If it is outside the living space, not in a spot you reach into, and you have identified it, the least-effort answer is often to seal the house properly and let it finish the job on its way out.