What Parts of a Home Are Most at Risk From Frozen Pipes?
Last updated October 26, 2026
The short answer
Unheated Spaces
Attics, basements, crawl spaces, and garages often contain exposed pipes that lack insulation. These areas are not heated, so temperatures can drop below freezing quickly. A pipe in an attic corner or a basement rim joist is especially vulnerable when outdoor temperatures fall.
Check for pipes running along exterior walls or near vents and gaps. Cold air can seep through small openings, chilling the pipe surface. If you live in Arlington, keep your shutoff valve location written down. Knowing where to turn off water can limit damage if a pipe bursts.
- Attic pipes near roof edges
- Basement pipes along outer walls
- Crawl space plumbing under floors
- Garage supply lines to outdoor faucets
- Pipes near unsealed vents or gaps
Exterior Walls and Cabinets
Pipes that run inside exterior walls are at risk because the wall cavity is colder than the room interior. Kitchen and bathroom cabinets that house pipes against an outside wall also trap cold air, especially if cabinet doors are closed. The lack of warm air circulation makes freezing more likely.
Open cabinet doors during freezing weather to let warm room air reach the pipes. Leave a slow trickle of water running from faucets connected to exposed pipes. Moving water is less likely to freeze. Insulating these pipes with foam sleeves can add a layer of protection.
- Pipes inside uninsulated exterior walls
- Under-sink pipes in outer-wall cabinets
- Supply lines to washing machines on cold walls
- Shower or tub pipes in unheated wall cavities
- Pipes in corners where two exterior walls meet
Outdoor Faucets and Hose Bibs
Outdoor faucets and hose bibs are directly exposed to freezing air. If you leave a garden hose attached, water can remain in the spigot and freeze, cracking the pipe or the valve. Even with a shutoff valve inside, the short stub outside can hold water.
Disconnect hoses before cold weather and drain the faucet. If your home has a frost-proof sillcock, the valve closes deeper inside the wall. For older faucets, use an insulated cover. This simple step can prevent a costly burst and the water damage that follows.
- Garden hose attached to outdoor spigot
- Faucets on unheated porches or decks
- Hose bibs on exterior walls without insulation
- Sprinkler system lines that remain filled
- Outdoor shower or pool supply lines
Pipes in Slab Foundations
Pipes that run under a concrete slab are usually safe because the ground below the frost line stays warmer. However, pipes that enter the slab from an exterior wall can freeze near the point of entry. The transition zone between cold outside air and the slab is the weak spot.
Seal gaps around pipes where they enter the foundation. Use expanding foam or caulk to block cold drafts. If you suspect a slab pipe has frozen, call a plumber to inspect it. A burst pipe under a slab can be difficult to detect, so watch for unexplained water pooling or damp spots on floors.
- Water main entering through a foundation wall
- Supply lines to a slab-on-grade bathroom
- Pipes near unsealed penetrations in the slab
- Lines running through an unheated crawl space
What to Do After a Burst
If a pipe bursts, shut off the main water valve immediately. Then open all faucets to drain the system and relieve pressure. Turn off the electricity if water has reached outlets or appliances. Dry the area as quickly as possible to reduce the chance of mold growth on soaked drywall and flooring.
Water from a burst pipe can soak into ceilings, walls, and carpets. Remove standing water and set up fans to dry surfaces. For extensive damage, local water damage pros can help with drywall repair, flooring removal, and thorough drying. Their work usually involves inspection, extraction, and drying before any rebuilding begins.
- Shut off the main water valve right away
- Drain faucets and flush toilets to empty lines
- Turn off electricity near wet areas for safety
- Mop up standing water and use towels or a wet vacuum
- Run dehumidifiers and fans to dry walls and floors
- See a doctor if you feel unwell from mold exposure
Talk to someone now
Phones are answered 24/7 for Arlington and nearby communities.
Call Now (703) 462-1739Frequently asked questions
At what temperature do pipes freeze?
Pipes can freeze when outdoor temperatures fall to 20 degrees Fahrenheit or below for several hours. But the actual risk depends on pipe location, insulation, and indoor warmth. If you see ice forming on exposed pipes, act quickly to prevent a burst.
How can I prevent pipes from freezing?
Insulate exposed pipes, seal gaps in walls, and open cabinet doors to let warm air circulate. Let a faucet drip slowly during extreme cold. Disconnect outdoor hoses and drain outdoor lines. These steps help keep water moving and reduce pressure buildup.
What should I do if a pipe bursts?
Shut off the main water valve immediately to stop the flow. Then drain faucets and turn off electricity in wet areas. Remove standing water and start drying surfaces. For major damage, local water damage pros can handle drying, flooring removal, and drywall repair. Policies vary, and your insurer decides what is covered.
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