How to Prevent Frozen Pipes in Winter
Prevent frozen pipes by insulating exposed pipes in unheated areas (attics, crawl spaces, garages) with foam pipe sleeves or heat tape, keeping your thermostat at 55 °F or higher when away, opening cabinet doors under sinks on exterior walls to let warm air circulate, and letting faucets drip during extreme cold snaps. Disconnect and drain outdoor hoses before the first freeze, and install frost-proof hose bibs ($50–$150 installed) to protect exterior plumbing. If your home has a history of frozen pipes, a licensed plumber can reroute vulnerable lines or add thermostatically controlled heat cables ($100–$400) for lasting protection.
Cost Breakdown
| Service | Low | High | Notes |
|---|---|---|---|
| Foam pipe insulation sleeves | $0.50 | $2 | Per 6-ft. section; polyethylene snap-on tubes |
| Thermostatically controlled heat cable | $50 | $150 | Plug-in, self-regulating; covers 6–30 ft. of pipe |
| Frost-proof hose bib installation | $100 | $150 | Per bib; includes labor and basic materials |
| Pipe rerouting (interior wall) | $300 | $1,500 | Permanent fix for chronically freezing runs; varies by length and access |
| Burst-pipe repair (emergency) | $500 | $3,000 | Pipe repair only; water damage restoration is additional |
Why Pipes Freeze and Burst
Water expands roughly 9 % when it freezes. That expansion creates enormous pressure inside a closed pipe — enough to split copper, CPVC, and even PEX. The burst typically happens downstream of the ice blockage, where trapped water has nowhere to go. Pipes most at risk are in unheated garages, crawl spaces, attics, and exterior walls with poor insulation.
Insulate Vulnerable Pipes
- Foam pipe sleeves: Pre-slit tubes of polyethylene foam ($0.50–$2 per 6-ft. section) snap over pipes in minutes. Cover every exposed pipe in unheated areas — both hot and cold lines.
- Fiberglass pipe wrap: Better for irregular fittings and bends. Wrap in overlapping layers and secure with foil tape.
- Thermostatically controlled heat cables: Plug-in cables ($50–$150) with a built-in thermostat turn on automatically when pipe temperature drops near freezing. Ideal for chronically vulnerable runs. Use only UL-listed products and follow the manufacturer's spacing instructions to avoid fire risk.
During a Cold Snap (Below 20 °F)
- Let faucets drip: A pencil-lead-thin stream of water through both hot and cold taps on exterior walls relieves pressure and keeps water moving. Costs roughly $0.05–$0.10 per day — far cheaper than a burst pipe repair.
- Open cabinet doors: Under kitchen and bathroom sinks on exterior walls, open the cabinet doors to allow heated room air to reach the pipes.
- Maintain heat: Keep your thermostat at 55 °F or above, even if you leave town. The heating cost is a fraction of a burst-pipe claim ($5,000–$70,000 average).
- Seal drafts: Caulk or spray-foam around holes where pipes penetrate exterior walls. Even small gaps let freezing air reach pipes.
Seasonal Prep Before Winter
- Disconnect garden hoses and drain the hose bib. Close the interior shutoff valve for the outdoor faucet if one exists.
- Drain sprinkler system supply lines using the system's blowout fitting or hire an irrigation company ($50–$100).
- Insulate the water-heater supply pipes in the first 6 feet from the tank to prevent heat loss and reduce freeze risk in unheated spaces.
- Know where your main shutoff valve is so you can cut water quickly if a pipe does burst.
When to Call a Plumber
If pipes have frozen repeatedly in the same location, a plumber can reroute them to an interior wall ($300–$1,500 depending on length and access). This is the only permanent fix for chronically exposed pipe runs. A plumber can also install frost-proof hose bibs ($100–$150 each installed) that self-drain when shut off.
Related Questions
At what temperature do pipes freeze?
Pipes can begin to freeze when the outside temperature drops below 20 °F (−7 °C), but the actual freezing point depends on insulation, wind exposure, and how long the cold lasts. Pipes in uninsulated exterior walls or crawl spaces can freeze at higher outdoor temperatures because wind chill and lack of heat accelerate cooling.
Does letting faucets drip really prevent frozen pipes?
Yes. A slow drip keeps water moving through the pipe and, more importantly, relieves the pressure buildup that causes bursting. It doesn't prevent ice formation entirely, but it prevents the catastrophic pressure spike. The water cost is negligible compared to burst-pipe damage.
Will PEX pipes freeze and burst like copper?
PEX is more freeze-resistant than copper because it can expand slightly, but it's not freeze-proof. Repeated freeze–thaw cycles weaken PEX fittings and connections. Insulate PEX pipes in unheated areas the same way you would copper.