Under the house, stop 3 of 7

Wrapping the pipes under the house

To insulate pipes in a crawl space, cover hot and cold lines alike, since Clemson says hot lines can freeze quicker¹. Insulated exposed pipes generally handle mild freezes down to 20°F. A cold spell of two days or more, or single digits, may still freeze them².

Kneel at the hatch and shine a light along the water lines to see which stretches are wrapped.

Updated November 4, 2026, Midlands House Walk

Foam pipe sleeves with tape at the seams, fixed beside wooden floor joists — Water pipes in gray foam with taped joints along the joists. Tape at the seams helps limit gaps where cold air gets in. AI-generated picture.

Unwrapped gray tubing running across joists with nothing around it — Gray flexible pipe running bare across wooden joists. Any material needs a look if it’s exposed to cold air like this. AI-generated picture.

Which stretches are bare?

Look for: Follow the lines from the point where they come through the foundation. Elbows, valves and short runs are the bits most often skipped.
What it tells you: Clemson’s 20°F figure is for insulated exposed pipes², so a bare run can’t count on it. If the pipe looks like this one, also read gray plastic pipe.

Bright new copper lines climbing a gray concrete block wall — New copper pipes running up a concrete block wall. Lines on a garage or outer wall need the same attention as those underneath.

Don't stop at the crawlspace

Look for: Check lines in the garage and along outside walls while you’re at it. A quick walk with a flashlight will show most of them.
What it tells you: Clemson names crawlspaces, garages and exterior walls together as the places to insulate¹. Piping buried 12 inches should never freeze in South Carolina², so the exposed runs are where to spend your effort.

Rusty foundation vent with shut louvers in brick, pine straw on the ground below — A rusty foundation vent with its louvers shut, pine straw below. Clemson’s advice is shut in winter, open again in spring. AI-generated picture.

Are the vents shut for the cold?

Look for: Before a hard cold spell, walk the outside wall and check each vent. Rust can stop louvers from closing fully, so try them gently.
What it tells you: Closing vents in winter and reopening in spring is Clemson’s advice¹. Wrapping does less if cold air is blowing straight across the pipes. Foundation vents has the summer side.

Plain wooden shed with a shingle roof beside a metal well pipe, pine trees around it — A small wooden pump house with a metal well pipe. The line from well to tank needs its own look on a freezing night. AI-generated picture.

On a well, check the line to the tank

Look for: Look at the run between the well and the pressure tank. Note any bare length in a shed or under the house.
What it tells you: Water in that stretch moves only when the pump runs. Clemson suggests about 6 gallons an hour to cycle the pump in poorly insulated spots².

If a pipe has burst, what comes first?

Go to the main shutoff. Burst pipes often go unnoticed until temperatures climb back above freezing¹, so listen for running water as it warms up. A freeze is coming lists the night-before checks, and your house shutoff shows where to look.

Flow Clemson lists to help keep a 1/2-inch pipe with 1/2-inch insulation from freezing, 20 feet exposed
Outside temperature	Flow needed	What that looks like
25°F	0.23 to 0.28 gallons an hour	About 0.25: a 3-ounce cup fills in 5 min 37 sec
5°F	0.57 to 0.68 gallons an hour	More than double. For scale, 1 gallon an hour fills the cup in 1 min 24 sec
Four faucets, 10 hours	1 gallon an hour each	About 40 gallons in all

Yours to do

Slip foam on any bare line you can reach from the hatch or in the garage, hot and cold, without going under. Skip it if the hatch shows standing water, sewage or live wiring, or you smell gas.
Find and test your main shutoff and the water heater shutoff before it freezes¹.
On a freezing night, let faucets run a little, hot and cold, using the flow in the table².

For a licensed pro

Wrapping long runs under the floor, or anything close to wiring.
A line that has frozen where you can’t reach it. Open faucets as Clemson says, and keep open flame well away.
Adding a house shutoff if you don’t have one, which the Columbia utility has recommended every property owner have³.

Where this comes from

Keep walking (AI picture)Gray plastic pipe: could it be polybutylene?