Pipes do not freeze evenly through a house. A supply line running through a heated interior wall next to a bathroom almost never freezes, even in a hard cold snap, because the surrounding framing stays close to room temperature. A line that runs along an exterior wall with thin or missing insulation, through a crawl space with open vents, or across an unheated garage ceiling is a different story. Those pipes sit in air that can drop well below freezing even while the thermostat reads 68 inside.
Which pipes freeze first
A lot of older homes in Passaic and Union County still run copper or PEX under the first floor through a vented crawl space. If the vents were not closed for winter and the space is not conditioned, the air down there can sit at outdoor temperature for days at a time.
A kitchen sink or a bathroom vanity built on an outside wall often has the supply line running inside that wall cavity with only the house wrap and siding between it and the cold. Older homes with less wall insulation than current code are the most exposed.
A line feeding a second floor bathroom sometimes travels through an unheated attic or a soffit over a bump out addition. These spaces lose heat fast and hold almost none of the house's warmth.
An attached garage that is not insulated well can drop close to outdoor temperature overnight. A hose bibb or a line feeding a washing machine in the garage is a common point of failure.
PEX tubing has a little more give than rigid copper when water inside it expands, but give is not the same as immunity. Both materials fail once ice fully blocks a section and pressure builds behind it, and a PEX fitting can pop loose just as a copper joint can split.
Prevention that works
A slow, steady drip from the faucet fed by a vulnerable line keeps water moving through the pipe. Moving water is much harder to freeze solid than water sitting still, and the drip also relieves pressure that would otherwise build against an ice blockage.
Under sink cabinets on exterior walls trap cold air against the pipe. Opening the doors during a cold snap lets warmer room air reach the supply lines, which is a free fix that takes a few seconds.
Gaps where pipes pass through a rim joist, a foundation wall, or a garage wall let outside air straight in. Spray foam or caulk around those penetrations, and close crawl space vents for the winter if the space is not actively conditioned.
A thermostat set no lower than the mid 50s, even in a vacant or second home, keeps interior wall cavities above freezing in most cases. Shutting the heat off entirely to save money during a cold stretch is one of the most common reasons we see a burst line in an otherwise well maintained house.
Where heat tape and insulation earn their keep
Pipe insulation sleeves help slow heat loss but do not add heat, so they work best on lines that are only marginally exposed, not on a pipe sitting in a cold crawl space or garage. For that level of exposure, self regulating heat tape wrapped directly on the pipe and plugged into a thermostatically controlled outlet adds actual warmth rather than just slowing the loss. Look for tape rated for continuous outdoor or wet location use, follow the wrap spacing on the packaging, and never run it on an extension cord or let the wrap overlap itself, since overlapped tape can overheat.
How to thaw a pipe safely
If a faucet produces no water and the pipe feels unusually cold to the touch, start by opening the faucet it feeds so steam and water have somewhere to go as the ice melts. Apply heat at the end closest to the faucet first and work back toward the blockage, using a hair dryer, a heat lamp held a safe distance away, or towels soaked in hot water. Never use a propane torch, a space heater left unattended against the pipe, or any open flame near a wall cavity, since that is how a frozen pipe call turns into a house fire call. If the pipe is inside a wall or ceiling and not reachable, or if there is no improvement after a reasonable effort, it is time to call a plumber rather than keep pushing heat at a wall from outside.
The moment a pipe bursts
- Shut off the main water valve immediately. Every minute it runs adds more water to the floor below.
- Open the nearest faucets to relieve pressure and drain the line faster once the main is off.
- Cut power to any outlet or fixture in the affected area if it is safe to reach the panel without stepping in water.
- Move anything movable off the floor and away from the wet area before it wicks further.
- Photograph the damage before anything is cleaned up or thrown out, for the insurance claim.
What to do in the first hours after that point, including how fast extraction needs to start and what a adjuster will want to see, is covered step by step in our guide on the first 24 hours after a burst pipe.
Why this matters more in New Jersey winters
New Jersey does not stay at one cold temperature all winter. A week of mild weather followed by a sudden hard freeze is a common pattern here, and that swing is harder on pipes than a steady deep cold, because homeowners relax their guard during the mild stretch and the cold snap catches an open vent or a thermostat turned down unnoticed. Towns with a lot of older housing stock, including parts of Paterson, Passaic, Elizabeth and Union, tend to have more exterior wall and crawl space exposure than newer construction, which is where we see the most frozen line calls each winter.
What we do
When a frozen line fails, the priority is stopping the water and starting extraction before it spreads under flooring and into a ceiling below. Our burst pipe service covers the emergency response, and structural drying follows once the source is secured and the area is measured for how far the water traveled.
This article is about Burst Pipe, Frozen Pipe and Appliance Leak Damage.