The short answer
The Freezing Sequence
Unheated areas lose heat quickly because they lack the warmth from your living space. Attics and garages often have poor insulation or none at all. When outdoor temperatures drop, these spaces cool down to match the outside air much faster than the rooms where you run a heater.
Water inside a pipe begins to freeze when the surrounding temperature stays below 32 degrees Fahrenheit. As ice forms, it expands by about nine percent. That expansion pushes against the pipe walls, creating pressure that can cause a crack or a complete burst. The process happens sooner in unheated zones because the cold reaches the pipe there first.
Why Ice Causes Bursts
The physics is straightforward: water is one of the few substances that expands when it freezes. In a closed pipe, the growing ice has nowhere to go. The pressure builds until the pipe fails, often at a joint or a weak spot.
You might think the pipe bursts because the ice expands along its length, but the real danger is the pressure that develops between the ice plug and a closed valve or fixture. That trapped water has no room to expand, so it pushes against the pipe wall. This is why even a small amount of ice can cause a major split.
- Ice expands about nine percent in volume
- Pressure builds between the ice and a closed end
- Pipes with joints or bends fail more easily
- Metal pipes can split, while plastic may crack
- A slow drip can relieve some pressure
- The longer the cold lasts, the higher the risk
Which Pipes Are Most at Risk
Pipes in unheated crawl spaces, attics, and garages are the most vulnerable. Exterior walls also expose pipes to cold, especially if insulation is missing or compressed. In Mesa, freezing is rare, but a sudden cold snap can still catch homeowners off guard.
Look for pipes running along outside walls or in cabinets under sinks that face an exterior wall. Pipes near vents or gaps that let cold air in are also at risk. If you live in Mesa, knowing where your shutoff valve is located can help you act quickly if a pipe does burst.
How to Protect Pipes
Insulation is your first defense. Wrap exposed pipes in foam or fiberglass insulation, and seal any gaps that let cold air reach them. Keeping a slow drip on faucets during freezing weather can also help, because moving water is harder to freeze.
For unheated areas, consider adding heat tape or a space heater, but follow safety instructions. If you leave your home for several days, set the thermostat to at least 55 degrees to keep interior walls warm. Even if you cannot heat every space, reducing the chill can delay the freezing process.
- Insulate pipes in attics and crawl spaces
- Seal air leaks around pipes and vents
- Let faucets drip during freezing weather
- Open cabinet doors to let warm air reach pipes
- Keep your thermostat above 55 degrees when away
- Know where your shutoff valve is
What to Do After a Burst
If a pipe bursts, turn off the main water valve immediately to stop the flow. Then call a plumber to repair the pipe. After the water is off, begin drying the area as soon as you can. Remove any standing water with towels or a wet vacuum to limit damage.
Water can soak into drywall, flooring, and insulation, leading to mold if left damp. For cleanup and drying, you may need the help of local water damage pros. They have equipment to extract water and dry out building materials. Policies vary, and your insurer decides what is covered, so check your policy to understand your options.
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Phones are answered 24/7 for Mesa and nearby communities.
Call Now (480) 898-4279Frequently asked questions
At what temperature do pipes freeze?
Pipes can freeze when the surrounding temperature drops to 32 degrees Fahrenheit or below. However, the actual freezing point inside a pipe depends on how cold it gets and how long it stays cold. Even at 20 degrees, a pipe in an unheated attic may freeze within hours.
How long does it take for pipes to freeze?
It varies based on insulation, pipe material, and temperature. In a poorly insulated attic, a pipe may freeze in as little as a few hours when it is very cold. In a heated home, it might take much longer. The key is to act before the temperature drops for an extended period.
Can a burst pipe cause mold?
Yes, any water damage can lead to mold if the area is not dried within 24 to 48 hours. Mold grows on damp drywall, wood, and carpet. If you have a burst pipe, dry the area quickly and consider a mold professional if you see or smell mold.