Pipes freeze and split when water inside them stops moving in a cold space. The risk is highest in the lines that run through exterior walls, unheated garages, crawl spaces and the attic. A seasonal calendar makes the checks routine: insulate and inspect in the early autumn, prepare for the first cold nights, watch during the cold, and check the damage after the thaw. Each month has a small set of jobs that prevent the loss most often seen in winter.
Key takeaways
- Pipes split most often in unheated or poorly insulated spaces, not in heated rooms.
- A pipe that froze and held can release its water on the thaw, often unseen in a wall.
- Know where the main shut-off is before the first freeze, and make sure it turns.
- Insulate exposed lines and seal the gaps where lines enter the house.
- After a cold snap, check the walls, the cabinets and the meter for signs of a split.
What happens in the autumn?
Autumn is the time to prepare. Find the shut-offs, insulate the exposed lines and seal the gaps where the pipes enter the house.
Walk the house and list the supply lines that run through an exterior wall, an unheated garage, a crawl space or the attic. Those are the lines most likely to freeze. Note which valves close, and which do not, because a valve that is stuck in winter is a bad discovery.
Insulate the exposed lines with foam sleeves, and wrap any line in a crawl space or attic that has no heat. Seal the gap where a line enters the wall with caulk or foam, because a draft in that gap can drop the temperature around the pipe below freezing on a cold night.
- Mark the main shut-off and every branch valve
- Insulate supply lines in cold spaces
- Seal gaps where lines enter exterior walls
- Disconnect garden hoses and close the hose-bib valves
- Note the location of any line in an outside wall
What should be done before the first hard freeze?
Open the cabinet doors under sinks on exterior walls, keep a low heat in the house and let a faucet drip on the coldest nights where a line is exposed.
On the coldest nights, open the cabinet doors under sinks that back onto an exterior wall, so room heat reaches the supply line. Keep the thermostat at a steady setting rather than letting the house cool down overnight. A house that is left cold for a day can freeze a line that would have stayed safe.
Let a faucet drip on the coldest nights where a line is exposed. A small, steady flow keeps the water moving so it is harder to freeze. The drip costs a little water, and it protects against a split that costs much more.
What should a homeowner watch during the cold?
Watch the water pressure, the meter and the walls. A drop in pressure, a meter that turns with every tap closed or a damp spot on a wall can all mean a line has frozen or split.
A drop in pressure at the fixtures can mean a line is partly frozen. Check the water meter with every tap and appliance closed, and note the reading in the morning and the evening. A change in the reading means water is leaving the system somewhere.
A damp spot on a wall, a cool wet floor or a cabinet that feels cold to the touch are signs to act on. Shut off the main valve if the spot is growing, and call for help.
What happens on the thaw?
On the thaw, the water that was held by ice is released, and a split line can spill a large volume within minutes. The thaw is often the time a split is found.
A line that froze and held may show no leak at all while the ice is in place. When the line warms, the water moves again through the split, and it can soak a wall or a floor before anyone notices. A warm day after a cold snap is therefore a good time to check the lines.
Check each line that was exposed during the cold. Look at the cabinet bases, the walls and the ceilings below the lines, and check the meter with every tap closed. Any sign of water should prompt the main valve to be closed and the line to be checked.
What should be done after the thaw if a pipe has split?
Close the valve that feeds the break, drain the line, remove the water and dry the wet material. The repair of the line is done by a plumber.
The valve feeding the break is closed first, and the line is opened at a fixture to release the pressure and any water left in it. The water on the floor and in the wall is removed and the structure is dried to a measured standard. The water-damage company does this part of the work.
The plumber repairs the line. Ask the plumber for the work order and the invoice, and keep them with the water-damage record. The permit questions for a new run of pipe are answered by the local building department.
What is the spring routine?
In spring, check the insulation and the seals, look at the lines that were exposed, and note the lines that froze so that they can be protected next winter.
Check the foam sleeves and the caulk around the lines, and replace any that have torn or dried out. Note which lines froze during the winter, because those are the lines to protect before the next winter, and the list can be used each year.
Keep the winter record with the house papers. A note of the cold snaps, the lines that froze and the work done is useful to the next owner and to any insurer that asks about the history of the house.
What should be done if a pipe freezes but does not split?
Keep the pipe warm and let the water move if a tap is open, but never use an open flame, and call a plumber if the flow does not return.
A line that has stopped flowing but has not split can often be thawed slowly. Open the nearest tap so that water can move once the ice gives, and warm the exposed section with a warm, dry source applied gradually. The heat should be applied to the frozen section rather than to the wall, and the homeowner should stand by the open tap to see whether the flow returns.
If the tap runs but the flow is weak, or if water appears anywhere along the line when it is warm, close the main valve and call a plumber. A line that has split while frozen will leak as soon as the ice releases, and the leak can be large.
Which insulation and protection choices suit an exposed line?
Foam sleeves suit most supply lines, while a heated cable or a thermostatically controlled heat tape suits a line that cannot be insulated well.
Foam pipe sleeves are inexpensive and easy to fit, and they work best on lines that run through a cold space and do not need to be accessed often. Lines in a crawl space or a garage that are hard to insulate may need a heated cable or heat tape controlled by a thermostat. The product should be installed to its maker's instructions, and a plumber or electrician can advise on the connection.
Heat tape and heated cable draw power, and they are a fire risk if they are damaged, covered by insulation they were not designed for or left on when they are not needed. Check them each autumn for damage, and do not bury a cable in insulation unless the product allows it.
What should a homeowner do during a long cold spell away from home?
Set the heat to a safe steady level, shut and drain the lines that can be drained and leave the cabinet doors open, and ask a neighbor to check the house.
A house left empty through a cold spell is at greater risk, because no one is there to notice a drip or a pressure drop. Keep the heat on at a steady level, not turned off. Where the house has lines that can be drained safely, a plumber can advise on draining them, and the main water can be shut off with a known drain at the lowest point.
A neighbor or a family member who has a key can check the house once or twice a day during the spell. Ask them to look at the lines in the garage, the crawl space and the lower bathroom, and to call if a sound or a wet spot is noticed.
How should the winter record be kept?
A simple log of cold nights, lines that were exposed, and any sign of a split, kept with the house papers, makes the next winter easier to plan.
A dated note of each cold snap, the lines that were protected, any fault found and the work done can be kept in a single file. Over several winters the file shows which lines are at risk and whether the protection works, which is useful both for the homeowner and for any insurer that asks about the history of the house.
The file is also a reminder. A homeowner who has written down the lines that froze last year is less likely to forget them in the first cold morning of the next winter.
Frequently asked questions
Can I thaw a frozen pipe with a torch?
No. An open flame near a pipe or a wall is a fire risk, and a torch can split a line. A warm, dry source applied slowly is safer, and a plumber can advise if the line has split.
Does a heated house still need insulation on the pipes?
Yes, where the pipe runs through an unheated or cold space such as the garage, the crawl space or the attic, even if the rest of the house is warm.
Will a space heater help?
A space heater near a pipe can be a fire risk. Keep it at a safe distance from the pipe and from anything that can burn, and never leave it running unattended.
Who answers the question about frost depth for a new line?
The local building department answers the questions about the depth and the permit for a new line. The frost depth for a given property is set there, and it is not stated on this page.
Sources
This guide is general information for El Paso County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.