How to Prevent Frozen Pipes

A single frozen pipe that bursts can dump hundreds of gallons into your walls and floors — the average winter water-damage claim runs well past $10,000. The good news: an afternoon of cheap, low-skill prevention almost always beats the plumber, the drywall crew, and the insurance deductible.

What you’ll need

• Foam pipe insulation sleeves — the main event; size to your pipe’s outside diameter (1/2 in. and 3/4 in. copper are most common)
• Outdoor faucet covers (hose-bib domes) — foam or hard-shell caps for every exterior spigot
• Self-regulating heat cable / heat tape — for pipes that have frozen before or run through a truly cold spot
• Fiberglass batt or foam board insulation — to pack around pipes and cold rim joists
• Exterior caulk and spray foam / adhesive — to seal the gaps where cold air reaches the pipes
• Weatherstripping — for the crawlspace hatch, garage door, and basement doors
• Electrical or foil tape and cable ties — to secure sleeves and heat cable (don’t seal foam seams with cheap duct tape alone)
• Utility knife and tape measure — to cut sleeves to length and mitre the corners
• Work light or flashlight and gloves — crawlspaces are dark and fiberglass itches
• A small space heater — optional, for a stubborn cold room on the worst nights (never leave one unattended)

Step 1: Find your main shut-off and know your risk pipes

Before anything else, locate your home’s main water shut-off — usually where the supply line enters the basement or crawlspace, or at the meter. Turn the handle to confirm it moves freely. If it’s a stiff old gate valve, add a quarter-turn ball valve to your list; a modern shut-off valve can be the difference between a mop-up and a catastrophe. Now walk the house and note the vulnerable pipes: anything running through an unheated basement, crawlspace, garage, attic, or an exterior wall, plus outdoor spigots and any line that has frozen before.

Pro tip: Tag the shut-off with a bright zip tie or label so anyone in the house can find it in the dark during an emergency. Everyone who lives there should know where it is.

Step 2: Insulate the exposed pipes

Foam pipe insulation sleeves are pre-slit — measure the run, cut a sleeve to length with your utility knife, and snap it over the pipe seam-side down. At corners and tees, mitre the ends at 45 degrees so the foam meets cleanly with no bare gap. Tape every seam and joint with foil or vinyl tape so cold air can’t sneak underneath. Don’t skip the elbows and valves — those uncovered fittings are exactly where a freeze starts. Hit both hot and cold lines; hot-water pipes freeze too.

Step 3: Add heat cable where insulation isn’t enough

For pipes in the coldest spots — or any line with a history of freezing — run self-regulating heat cable along the pipe before you insulate over it. Modern self-regulating cable adjusts its own output and won’t overheat, unlike old constant-wattage tape. Follow the manufacturer’s instructions exactly: most run the cable straight along the bottom of the pipe (or spiral-wrapped at the spacing they specify), secure it with the included clips or high-temp tape, then cover with foam sleeve. Plug it into a dedicated GFCI outlet.

Safety: Only use heat cable rated for potable water pipes, never overlap it on itself, and never run it under standard foam unless the product says it’s compatible. If any wiring looks cracked or the cable is more than a few years old, replace it — don’t gamble with an electrical heat source in a wall cavity.

Step 4: Seal the cold-air leaks reaching your pipes

Insulation on the pipe means nothing if a 20-degree draft is blowing across it. Find the gaps — where the supply line penetrates the foundation, around dryer vents and sill plates, cracks in the rim joist, gaps under the crawlspace hatch. Seal small gaps with exterior caulk and larger ones with expanding foam. Add weatherstripping to the crawlspace access, garage service door, and any basement door. Pack loose fiberglass batt around pipes that run through exterior walls or a cold rim joist. Close crawlspace vents for the winter if your climate calls for it.

Step 5: Winterize the outdoor faucets and hoses

Disconnect every garden hose — a hose left attached traps water in the spigot and is one of the most common burst points. Drain and store your hoses for the season. If you have interior shut-offs for the outdoor lines, close them and open the outside spigot to drain it. Then cap each exterior faucet with a foam faucet cover. Frost-free sill cocks still benefit from a cover, and if you have an in-ground irrigation system, that’s a separate winterization job (see the related guide below).

Step 6: Set your deep-freeze routine

On nights the forecast drops into the teens or below, do three things. Open the cabinet doors under kitchen and bathroom sinks so household heat reaches the pipes in exterior walls. Let the faucet farthest from your water main drip a slow pencil-lead stream — moving water resists freezing and relieves pressure. And keep the thermostat at a steady temperature day and night; never let the house drop below about 55°F, even when you’re away. Traveling for the holidays? Leave the heat on, or shut off the water at the main and drain the lines.

Frequently asked questions

A weekend of foam sleeves and caulk is the cheapest insurance you’ll ever buy against a burst pipe. If you’re unsure about heat cable, sizing a shut-off valve, or you need a faucet cover before tonight’s freeze, your local independent hardware store can point you to the right part in five minutes — or ask us here.