If a frozen pipe bursts, shut off the water at the main valve before you do anything else. The main is usually at the water meter or where the line enters the house, and the faucets stay open until the pipe is repaired.
This guide covers what comes before and after that moment: which pipes in a North Jersey house freeze, what to do before the first hard cold snap, how to leave for Thanksgiving or Christmas without coming home to a flood, how to thaw a pipe without starting a fire, and who to call once water is on the floor.
We are a roofing, window and glass contractor, not plumbers, and this post says so where it matters. The pipe belongs to a licensed plumber. Our part is the water damage that follows.
Which pipes freeze in a North Jersey house, and at what temperature
Water expands as it freezes, and that pressure can split metal or plastic pipe. The American Red Cross lists the pipes that freeze most often: outdoor hose bibs and other lines exposed to severe cold, supply pipes in unheated areas such as basements, crawl spaces, attics, garages and kitchen cabinets, and pipes against exterior walls with little or no insulation. In an older North Jersey house, start with the back-wall hose bib, a kitchen sink on an outside wall, any line in an unheated garage, and the crawl space under an addition.
There is no single outdoor temperature at which a house is in trouble. A freezing-pipes brochure from the Insurance Institute for Business & Home Safety (IBHS) cites University of Illinois Building Research Council field tests in which uninsulated pipes in an unconditioned attic began to freeze when the outside temperature fell to 20 degrees F or below. IBHS calls that a "temperature alert threshold" mainly for southern houses, since northern houses are generally built with the pipes inside the insulation. The catch is its own warning: pipes exposed to cold air through cracks in an outside wall, or with no insulation, can freeze above 20 degrees F, especially when the air is moving on a windy day. A gap and a breeze matter as much as the number on the thermometer.
IBHS also explains why the split often shows up where there is no ice. Once ice blocks the pipe completely, continued freezing raises the water pressure between the ice and a closed faucet downstream, and the pipe usually bursts where little or no ice has formed.
Before the cold snap: what to do this month
Most of this takes an afternoon.
- Hoses and hose bibs. Remove, drain and store hoses. The Red Cross says to close the inside valve feeding each outdoor hose bib, then open the outside bib so the leftover water drains, and to keep the outside valve open so any water left in the pipe can expand without breaking it. IBHS adds that if an outside faucet has no shut-off valve inside the house, a plumber can install one.
- Insulate what you can reach. Check the garage and under kitchen and bathroom sinks for supply lines in unheated spots, and insulate both hot and cold pipes. IBHS says to leave no gaps in the sleeve that expose the pipe to cold air.
- Heat tape or heat cable. The Red Cross says to use a UL-listed product. IBHS says to follow the maker's instructions carefully to avoid the risk of fire, and to prefer one with a built-in thermostat, since a cable without one has to be plugged in each time and can be forgotten.
- Seal the gaps. IBHS says to caulk cracks and holes in outside walls and foundations near water pipes, and names the holes where television, cable or telephone lines come through the wall. It is the same cold-air hunt as fixing drafty windows, so do both in one pass.
- Close the garage door if supply lines run through the garage.
- Open the cabinet doors under sinks on exterior walls during cold spells, after moving cleaners and chemicals out of children's reach.
- Drip on the worst nights. Let cold water drip from a faucet served by an exposed pipe. The Red Cross says even a trickle helps; IBHS adds that water can still freeze with a slow flow, and the bigger benefit is that an open faucet relieves the pressure that bursts the pipe. Where one spout has both hot and cold lines, let both drip. If the drip stops, leave the faucet open, because the pipe may have frozen and still needs that relief.
Leaving for Thanksgiving or Christmas
Do not turn the heat off or far down while you are away. The Red Cross says to leave the heat on, set no lower than 55 degrees F. When you are home in cold weather, it says to hold the same temperature day and night rather than dropping it overnight: the heating bill may run higher, but a burst pipe is a much more costly repair.
For a long absence IBHS offers a more thorough option: drain the system. Shut off the main valve and open every fixture, hot and cold, until the water stops running. With no water in the pipes, nothing freezes. When you get home, turn the main back on and let each fixture run until the pipes are full again. If you are not sure what draining will mean for your water heater or boiler, ask a plumber before you try it.
Ask someone with a key to check the house every couple of days, and show them the main shut-off before you leave.
Town sidewalk-clearing deadlines run whether or not you are home, so arrange the walk and driveway before you go; our snow removal page lists the deadlines for 15 North Jersey towns.
How to thaw a frozen pipe that has not burst
If you turn on a faucet and only a trickle comes out, suspect a frozen pipe. The Red Cross says the likely spots are against exterior walls or where the water service enters through the foundation. If nothing comes out at all, IBHS says not to take chances and to call a plumber.
To thaw it, keep the faucet open so running water helps melt the ice, then apply heat to that section of pipe. The Red Cross lists four ways: an electric heating pad wrapped around the pipe, an electric hair dryer, a portable space heater kept away from anything flammable, or towels soaked in hot water. IBHS says to apply the heat slowly, starting close to the faucet end and working toward the coldest section.
Never use a blowtorch, a kerosene or propane heater, a charcoal stove or any other open flame. IBHS warns that a flame will damage the pipe and may start a building fire, and that you should not use electrical appliances while standing in water.
Keep heating until full water pressure returns, then check every other faucet in the house, since the Red Cross notes that if one pipe freezes, others may too. If you cannot find the frozen section, cannot reach it, or cannot thaw it, call a licensed plumber. As it thaws, watch the pipe and the wall or ceiling around it for water.
What to do in the first hour after a pipe bursts
Water running that you cannot account for, or a stain spreading across a ceiling, is a burst pipe until you know otherwise.
- Shut off the main. Turn off the water at the main shut-off valve, usually at the meter or where the line enters the house, and leave the faucets open until repairs are done.
- Think about electricity before you step into water. Ready.gov's flood guidance says not to touch electrical equipment if it is wet or if you are standing in water, and to turn off the electricity only if it is safe to do so. If the panel is in a flooded basement, do not wade to it; call your utility or an electrician.
- Photograph before you move anything. Photos and video of the pipe, the water and every damaged surface are what your claim will lean on.
- Get belongings out of the water. Lift furniture off wet floors and move rugs, boxes and electronics somewhere dry.
- Start removing water. Towels, mops and buckets are safe. Plug nothing in while the floor is wet.
- Call a plumber for the pipe, and a water damage company for the drying if more than a small area is wet.
Who does what: the plumber, the restoration crew and us
A burst pipe is two jobs. Repairing or replacing the pipe is plumbing work. New Jersey licenses master plumbers through the State Board of Examiners of Master Plumbers, whose rules at N.J.A.C. 13:32 are adopted under N.J.S.A. 45:14C-7. Hire a licensed plumber and ask for the license number. We are not plumbers and we do not touch the pipe. This is general information, not legal advice.
Removing the water, drying the structure, cutting out what cannot be saved and rebuilding is restoration work, and that is the part we do. Our water damage restoration page explains extraction, drying, mold and the rebuild, with county pages for Bergen County and Passaic County.
Speed matters because of mold. The U.S. EPA says that if wet or damp materials are dried within 24 to 48 hours of a leak, in most cases mold will not grow. Start on the water while you wait.
Is a burst pipe covered by homeowners insurance?
Report the loss promptly, photograph everything and keep receipts. Flood is a separate question: New Jersey's required flood-coverage notice, N.J.A.C. 11:1-5.5, states that a homeowners policy does not cover flood damage. Whether your policy covers a burst pipe, and what it excludes, only your carrier can tell you. This is general information, not legal advice, and we do not give coverage opinions.
After it is dry: the stain that shows up later
Water from a pipe inside a wall or ceiling does not always show where it started. After a freeze or a burst, watch the ceilings and walls around that run for the rest of the winter for a new stain or bubbling paint. Our guide to house problem symptoms helps you tell a plumbing stain from a roof leak and judge how urgent it is.
Sources (read October 20, 2026)
Every figure and instruction above comes from one of these.
- American Red Cross, Preventing & Thawing Frozen Pipes: https://www.redcross.org/get-help/how-to-prepare-for-emergencies/types-of-emergencies/winter-storm/frozen-pipes.html
- Insurance Institute for Business & Home Safety, Freezing and Bursting Pipes (brochure citing University of Illinois Building Research Council research; copy hosted by the City of Paola, Kansas): https://cityofpaola.com/DocumentCenter/View/1270/How-to-prevent-freezing-bursting-pipes
- Ready.gov, Floods: https://www.ready.gov/floods
- U.S. EPA, A Brief Guide to Mold, Moisture and Your Home: https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home
- NJ Department of Banking and Insurance, Notice Regarding Flood Damage Coverage, N.J.A.C. 11:1-5.5: https://www.nj.gov/dobi/division_consumers/insurance/floodreq.htm
- New Jersey Register, State Board of Examiners of Master Plumbers, readoption of N.J.A.C. 13:32, 54 N.J.R. 628(a), April 4, 2022: https://www.njconsumeraffairs.gov/Adoptions/plumbado_04042022.pdf