How to Prevent Frozen Pipes
A burst pipe is the most expensive winter disaster most homeowners face—average claims run $10,000–$25,000 and some exceed $100,000. The good news: freezing is almost entirely preventable with basic attention to heat, insulation, and air sealing. Do the prevention work in fall and you can stop worrying about it.
Quick Summary
Time Required
90 minutes
Difficulty
Easy
Cost
$30–$100 insulation supplies
Maintaining 55°F+ Throughout the Home
Heat is your primary defense. Never let any area of the home drop below 55°F when water is in the pipes.
Keep heat on in every room
Closing vents in unused rooms saves a little heat but freezes pipes inside those walls. Keep every room above 55°F, doors open, and vents open.
Set travel temperatures to 55°F minimum
When away, never drop the thermostat below 55. The few dollars saved on heating bills are trivial compared to even a minor pipe burst.
Add supplemental heat to trouble spots
Unheated basements, garages with plumbing, and bonus rooms over garages benefit from a small electric space heater set on low during extreme cold.
Opening Cabinets on Exterior Walls
Kitchen and bathroom sinks on exterior walls have supply pipes running through the cold wall cavity. Warm air must reach them to prevent freezing.
- Which cabinets to open: Kitchen sink cabinets on exterior walls, bathroom vanities against outside walls, and any laundry room cabinets near outdoor plumbing.
- When to open them: Whenever temperatures drop below 20°F. In very cold climates (below 0°F), leave them open all winter.
- Secure items safely: Move cleaners, chemicals, and anything dangerous to children or pets out of reach when cabinets stay open.
- Pair with dripping faucets: On the coldest nights, combine open cabinets with dripping faucets for maximum protection.
- Watch for condensation: Water droplets on cabinet walls mean warm room air is meeting cold surfaces—usually a sign you need pipe insulation, not just open cabinets.
Insulating Exposed Pipes
Foam pipe sleeves are the cheapest and fastest protection for any pipe you can see and reach.
Identify at-risk pipes
Walk the basement, crawl space, attic, and garage. Look for copper or PEX pipes running through unheated or drafty areas. North-facing walls are highest priority.
Match sleeve size to pipe diameter
Pipe sleeves come pre-slit for 1/2-inch, 3/4-inch, and 1-inch pipes. Measure carefully. Loose sleeves lose half their insulation value.
Seal joints and overlaps with tape
Wrap joints with foil-faced duct tape. Every unsealed gap is a cold bridge that defeats the insulation.
Consider heat tape for extreme cases
Pipes in consistently freezing locations benefit from thermostatic heat cable that turns on at 38°F and adds direct warmth. $30–$80 per pipe.
Sealing Air Leaks Near Pipes
Still cold air takes longer to freeze a pipe than moving cold air. Draft sealing can be the difference between frozen and fine.
- Rim joist inspection: The rim joist (where foundation meets floor framing) is the single biggest source of basement drafts. Stuff with rigid foam or spray foam any gaps between sill plate and framing.
- Pipe penetrations through exterior walls: Outdoor hose bib pipes, washing machine lines, and vent stacks all punch holes in the building envelope. Seal around each with expanding foam.
- Dryer vent and outside hoods: Broken dryer vent flaps let cold air pour in. Replace flapper and seal around the outside hood.
- Basement windows and doors: Weatherstrip or insulate with removable foam covers for the winter.
- Electrical outlets on exterior walls: Install foam gaskets behind the outlet covers to stop cold air infiltration through the gang box.
Pro Tips
- •Shut off hose bibs in fall: Drain outdoor spigots, close the interior shutoff, and cover with insulated hose bib covers. Frozen exterior valves burst supply pipes inside the wall.
- •Label your main shutoff: Tape a bright sign above the main water valve. In an emergency you or a house-sitter need to find it in 10 seconds without thinking.
- •Use smart thermostats for travel alerts: Models like Ecobee and Nest send a phone alert if home temp drops below a threshold. A $150 upgrade that saves $15,000 claims.
- •Install a whole-home water alarm: Shut-off devices like Flo by Moen detect leaks and auto-close the main supply. Insurance companies often offer discounts for installation.
Frequently Asked Questions
At what temperature do pipes freeze?
Pipes generally start to freeze when exposed to sustained temperatures of 20°F or below, though copper and iron pipes in well-insulated spaces can tolerate lower. PEX and PVC handle freezing better than copper. The real risk factor is wind chill and drafts—an exposed pipe in a drafty crawl space at 28°F freezes faster than a pipe in a sealed wall cavity at 18°F. The 20-degree rule is a starting point for when to actively protect pipes.
Should I leave heat on when away in winter?
Yes, always. Set the thermostat to at least 55°F when traveling. Lowering heat saves 5–10% on bills but risks catastrophic freeze damage. If a pipe bursts while you are gone, water can flow for days, causing tens of thousands in damage. For extended absences, also shut off the main water supply and drain lines, or ask a neighbor to check the house every 48 hours. The savings from dropping below 55°F are not worth the risk.
Which pipes are most likely to freeze?
The highest-risk pipes are those in unheated spaces (basements, crawl spaces, attics, garages, exterior walls) and those near air leaks. Specifically, watch outdoor hose bibs, pipes running through uninsulated exterior walls (especially kitchen sink walls and bathroom plumbing on outside walls), pipes in unheated basements, and anywhere you can feel a draft. North-facing walls freeze sooner than south-facing. Pipes that have frozen once are more likely to freeze again unless you address the underlying issue.
Related Guides
Winter Maintenance Checklist
Complete 20-step guide to staying comfortable and safe all winter
Identify and Thaw Frozen Pipes
Recognize the signs, shut off main water, and safely warm the frozen section
When and How to Drip Faucets
Below 20°F, which faucets to drip and at what flow rate
Clear Snow from Your Roof Safely
When to rake, when to hire help, and warning signs of structural overload