How Do I Keep Pipes From Freezing in Winter?

To keep pipes from freezing, insulate every exposed run in cold zones (crawl spaces, attics, garages, exterior walls), seal the drafts around them, and drip the faucets they serve when temperatures drop into the teens or below. Keep the thermostat at 55°F or higher when you’re away, and open cabinet doors on exterior walls so warm air reaches the pipes. A few hours of prevention beats a flooded basement.

Why pipes burst — it’s not the ice, it’s the pressure

Water is unusual: it expands about 9% when it freezes. In a pipe, the ice plug itself doesn’t cause the break — the pressure of trapped water between the ice blockage and a closed faucet does. That pressure can spike to thousands of pounds per square inch, and the pipe fails at its weakest point — often not where the ice formed. An eighth-inch crack can dump 250 gallons of water a day — destroying drywall, flooring, and anything stored nearby before you notice. Frozen pipes are America’s most common winter plumbing disaster, and almost entirely preventable.

Which pipes freeze first

Not all plumbing is equally at risk. Prioritize:

• Exterior-wall runs. Chilled from both sides — the #1 freeze location.
• Crawl spaces. Cold air circulates freely; supply lines and hose bibbs are exposed.
• Attics. Supply runs to upstairs bathrooms pass through frigid attic space.
• Garages. Typically unheated; lines to utility sinks or laundry are common victims.
• Outdoor faucets (hose bibbs). The short stub line to an outdoor spigot freezes fast — and it’s attached to your interior plumbing.
• Any run near a draft — foundation vents, dryer vents, pet doors, or cable-entry gaps. Wind chills pipes below ambient.

The pattern: exposure + wind + low flow. The least-used line in the coldest spot (a guest-bath line in an exterior wall) is always the first casualty.

Tools & materials you’ll need

• Foam pipe insulation sleeves (pre-slit tubular kind) — 1/2" and 3/4" sizes to match your pipes
• Pipe insulation tape or zip ties for joints
• Expandable spray foam or caulk for sealing gaps
• UL-listed heat tape (self-regulating type) for the highest-risk runs
• Flashlight or headlamp for crawl spaces; hair dryer (for thawing, if needed)
• Optional: pipe thermometer or freeze alarm that alerts your phone near freezing

Total DIY cost: $30–$80 for a typical home’s exposed runs.

Step 1: Insulate exposed pipes with foam sleeves

Pre-slit foam pipe sleeves are the cheapest, easiest win — roughly $0.50–$1 per foot at any hardware store.

1. Measure your pipe diameter (the copper or PEX itself, not including existing fittings): common sizes are 1/2" and 3/4".
2. Cut the foam sleeve to length with a utility knife. Slit the tube along the pre-cut seam and press it around the pipe.
3. Butt sections tightly end-to-end — any gap is a freeze point.
4. Seal joints and corners with pipe insulation tape.
5. Focus on crawl spaces, attics, garages, basements near foundation walls, and outdoor bibbs.

One caveat: insulation slows heat loss — it doesn’t create heat. In a wind-whistled crawl space, foam alone may not be enough without sealing drafts first (Step 2).

Step 2: Seal air leaks around the pipes

Cold air infiltration is the other half of the equation. With your flashlight, inspect everywhere pipes run and seal the gaps:

• Where pipes pass through walls, floors, or the foundation — fill gaps with expandable spray foam ($5–$8 a can).
• Foundation and crawl-space vents — cover vents that direct wind at plumbing (reopen in spring).
• Cable and utility penetrations — caulk the holes where phone, cable, or gas lines enter; they often leak cold air onto nearby pipes.
• Dryer vents and pet doors — check that they close and seal properly; both funnel cold air inward.

Step 3: Install heat tape on the highest-risk runs

Heat tape (also called heat cable) is an electric warming cable that wraps along a pipe to keep it above freezing. Use it for the runs that worry you most — the exterior-wall stub to the outdoor spigot, a crawl-space main, a garage line.

Safety rules — read these first:

• Follow the manufacturer’s instructions exactly — overlap spacing, thermostat placement, and plug requirements matter. Never overlap non-self-regulating tape, which can overheat.
• Plug it into a GFCI-protected outlet. Avoid extension cords; if unavoidable, use a heavy-duty outdoor-rated cord.
• Never insulate over heat tape unless the instructions allow it. Over-insulating the wrong tape traps heat and can cause failure or fire.
• Inspect annually and replace tape that’s cracked, brittle, or more than a few years old.

Heat tape runs $25–$60 for a typical kit.

Step 4: The drip trick — when and how

When a serious cold snap hits (single digits or teens °F, especially with wind), let vulnerable faucets drip — both hot and cold lines serving the cold zone. A thin, steady drip keeps water moving so pressure can’t build. A slow but visible drip (about the width of a pencil lead) is enough; a full stream wastes water without adding protection. The drip costs pennies per night; a burst pipe costs thousands.

Also on the coldest nights: open cabinet doors under sinks on exterior walls so room heat reaches the pipes, and close the garage door if you have supply lines in or near the garage.

Step 5: Set your thermostat right — especially when away

Never set the thermostat below 55°F when you’re away — the most common frozen-pipe mistake among vacationers. A house at 50°F still lets exterior-wall cavities drop below freezing on a bitter night.

Away for a night or two: keep it at 55–60°F minimum. Away for a week or more: 55°F minimum, drip the highest-risk faucets, and have someone check the house. Many insurers require regular check-ins or maintained heat for winter water-damage coverage. Away all winter: consider draining and shutting off the water entirely (a plumber can do a full winterization). No water in the pipes = no burst pipes.

How to thaw a frozen pipe safely

You discover a faucet that gives nothing but a hiss of air — a pipe has frozen. Thaw it now, before the ice plug generates burst-level pressure.

1. Open the faucet the frozen section serves — even a trickle helps melt the ice and gives thawing water somewhere to go.
2. Apply heat gently from the faucet end back toward the ice: a hair dryer on medium is the classic tool. Electric heating pads or hot towels work too.
3. Never use an open flame. Blowtorches are the #1 cause of thawing-related house fires — too much heat ignites insulation or joists.
4. Watch for leaks as you go — the pipe may already have cracked, and the leak appears as it thaws. If water sprays, shut the main water valve immediately.
5. Keep heating until full pressure returns, then check for drips over the next few hours.

If you can’t find the frozen section, or it’s inside a wall, call a plumber rather than tearing into drywall blind.

What this costs

Fix	Typical DIY cost
Foam pipe insulation sleeves (~50 ft)	$15–$30
Pipe insulation tape	$5–$8
Caulk / expandable spray foam for sealing gaps	$5–$10
Heat tape kit (UL-listed, self-regulating)	$25–$60
Pipe thermometer / freeze alarm	$20–$40
Plumber visit (thawing or repair)	$150–$400
Burst-pipe water damage restoration	$2,000–$10,000+

Safety warnings

• Heat tape is electrical. GFCI outlet, manufacturer instructions, annual inspection. Faulty or misused heat tape is a fire risk.
• Never thaw with an open flame. Blowtorches near walls have burned down houses. Hair dryer only.
• Know where your main water shutoff is before an emergency. Label it. Everyone in the house should be able to find it blindfolded.
• Don’t pour boiling water on a frozen outdoor pipe — thermal shock can crack it, and the water can refreeze into a bigger problem.

Frequently asked questions

At what temperature do pipes freeze? Standing water in an unprotected pipe starts freezing around 20°F in practice — pipes can hold out a bit below 32°F if they’re insulated and the water isn’t stagnant, but 20°F is the danger threshold where bursts happen fast. Wind chill on exposed runs makes it worse.

Should I drip hot water, cold water, or both? Drip both if the lines run through a cold zone — hot and cold are separate runs and each can freeze. Drip the cold line at minimum, since it’s most often in exterior walls.

Do I need to drip faucets every night all winter? No — only when it’s genuinely bitter: roughly below 20°F, or teens with high wind, or when your house has a known vulnerable run. Drip the faucets served by those runs. On a mild 35°F night, normal heating is plenty.

Does insulating pipes really help if the crawl space stays freezing? Partially — insulation only slows heat loss; it can’t warm a pipe. In truly cold zones, combine insulation with draft sealing and heat tape on the riskiest runs.

My outdoor faucet has a “frost-free” sillcock. Am I safe? Frost-free sillcocks move the shutoff valve 8–12 inches inside the warm wall — much better than standard bibbs, but not magic. Disconnect hoses every fall regardless: a connected hose traps water in the stem, which freezes and bursts even a frost-free faucet. Add a foam faucet cover ($3–$5).

What should I do if I’m going on vacation in winter? Keep the thermostat at 55°F or higher, drip the highest-risk faucets, open exterior-wall cabinet doors, disconnect outdoor hoses, and arrange for someone to check the house. Many policies exclude freeze damage if the heat was off or the house unchecked.

Prevention tips for every fall

• Fall routine: disconnect all outdoor hoses; install foam faucet covers; inspect and re-tape insulation; test heat tape before the first freeze.
• Check the shutoffs: know where the main water shutoff and outdoor-spigot valves are, and confirm they turn freely. A valve that hasn’t moved in five years may seize when you need it.
• Seal new gaps from recent work — cable installers punch holes everywhere.
• Consider a leak detector: $25–$50 water alarms under sinks and near the water heater alert you to the first drip.

When to call a pro

Call a plumber if: the frozen pipe is inside a wall or unreachable, thawing reveals a leak, multiple fixtures are affected (the blockage may be in the main line), you see a bulging or cracked pipe, or water is spraying and you can’t find the shutoff. For burst-pipe damage, a plumber repairs the pipe ($150–$400 typical) and a restoration company handles the water damage — call both, and call your insurance company early.