A short checklist can protect the pipes in a cold spell and make a split easier to manage. It covers the lines in exterior walls, the heat in unused rooms, the shut-off, and the readings to take after a thaw. Review it each autumn and after any split.
Key takeaways
- Know where the main shut-off is before a cold spell
- Keep the heat on in rooms with pipes on outside walls
- Insulate exposed lines and seal wall openings
- Check for damp patches and water sounds after a thaw
- Call the line and a plumber if a line has split
Before the cold arrives
Find the shut-off, insulate exposed lines and keep heat in the rooms that hold pipes.
The best protection is in place before the first hard freeze. Find the main water shut-off and the shut-off for each fixture, and check that each one turns. Insulate exposed lines in unheated spaces, and seal openings where a line passes through an outside wall.
Keep the heat on in rooms that hold pipes on outside walls, even when the house is unoccupied. A plumber can advise on heat tape for exposed runs where it is appropriate.
- Find and test the main shut-off
- Insulate exposed lines in unheated spaces
- Seal openings where lines pass through outside walls
- Keep heat on in rooms with pipes on outside walls
- Ask a plumber about heat tape for exposed runs
During a hard cold spell
Keep the cabinet doors under sinks open on outside walls, let a tap drip and watch for signs of a freeze.
On the coldest nights, open the cabinet doors under sinks on outside walls so warm air reaches the lines. Let a tap drip slowly on a line that runs in an outside wall, because moving water is less likely to freeze.
Watch for signs of a freeze: a tap that gives little or no water, a damp patch on a wall or ceiling, or a sound of water running inside a wall when no fixture is open.
- Open cabinet doors under sinks on outside walls
- Let a tap drip on a line in an outside wall
- Check for a tap giving little or no water
- Watch for a damp patch on a wall or ceiling
- Listen for running water with no fixture open
If a line freezes
Do not light an open flame near the line, shut off the water if the line has split and call a plumber.
If a line is frozen but not split, warm it slowly with a hair dryer or heated air, starting from the tap end. Never use an open flame near a pipe or a wall. If a line has split, shut off the water at the main or the nearest valve, open a tap and call a plumber and the line.
Once the water is off, keep the house warm enough for the drying to run, and do not turn the heat down in the affected room.
- Warm a frozen line slowly, starting at the tap
- Never use an open flame near a pipe
- Shut off the water at the main if a line has split
- Open a tap to relieve the pressure
- Call a plumber and the 24/7 line
After a thaw
Check for damp patches, staining and water in the lowest rooms after a thaw.
A thaw can reveal a split that was hidden by the cold. Check each wall that holds a line, the ceiling below any upstairs line and the floor near the outside walls. A damp patch that appears days after the thaw can be a split inside the wall.
Photograph anything you find, with the date, and call the line if the readings you can see are not clear.
- Check walls that hold a line for damp
- Check ceilings below upstairs lines
- Check floors near outside walls
- Photograph any damp area with the date
- Call if a damp area is not clear
Records and a yearly review
Keep a note of the shut-off, the insulated lines and the rooms kept heated, and review it each autumn.
A short note of where the shut-off is, which lines are insulated, which rooms are kept heated and which wall has split before is the record a plumber and an insurer will want. Keep it with the house papers.
Review the note each autumn, and after any split. A house changes over time, and the note must change with it.
- Where the main shut-off is
- Which lines are insulated and how
- Which rooms are kept heated in a cold spell
- Which wall has split before, and when
- A yearly review each autumn
Lines in exterior walls and the cold side of the house
The lines that run in exterior walls, under the house or along the cold side are the ones to check first.
Not every line is at the same risk. A line that runs inside an exterior wall, through an unheated crawl space or along the cold side of the house is the one most likely to freeze, because it is cooled from outside and has little warmth from the room. The check starts with those lines and the place where each one enters the house.
Look for gaps where a line passes through the wall or floor, for a missing or torn insulation sleeve, and for a cold draught that you can feel near a pipe. Each gap is a path for cold air to reach the line, and it is worth sealing before the cold arrives.
- Lines in exterior walls and cold corners
- Lines in unheated crawl spaces and garages
- Gaps where lines pass through the wall or floor
- Torn or missing insulation sleeves
- Cold draughts felt near a line
Keeping rooms warm enough in a cold spell
Heat is kept on in every room that holds a line, including rooms that are not used.
A closed room with a line in an outside wall can fall below freezing even when the rest of the house is warm. Keep the heat on at a steady level in each room that holds a line, and keep the doors to those rooms open so warm air can reach them. A thermostat set low to save fuel is a common cause of a split line.
If the house will be empty for a time in winter, set the heat to a level that keeps the lines safe and check the house on a schedule. An empty house with the heat off is the most common setting for a split that runs unseen.
- Keep heat steady in rooms that hold a line
- Open doors to rooms that hold lines
- Do not set the thermostat too low at night
- Set a safe level if the house will be empty
- Check the house on a schedule while empty
Drip, drain and shut-off
A slow drip, a drained outside line and a known shut-off are the three steps that prevent most damage.
On the coldest nights a slow drip from a tap on a line in an outside wall keeps the water moving, which makes a freeze less likely. Drain any outside tap and its supply before the first hard freeze, and close the valve that feeds it if one is fitted.
Know where the main shut-off is, and test that it turns before winter. A shut-off that is stuck or seized is no use in an emergency, and a homeowner who finds it on the day loses time.
- A slow drip on a line in an outside wall
- Drain any outside tap and close its supply valve
- Find the main shut-off before winter
- Test that the main shut-off turns
- Know the shut-off for each fixture
A short plan for the week after a split
The first week after a split is about the water, the wet area and the records, in that order.
Once the split is shut off and the crew has found the wet area, the first week is about keeping the drying on track and the record complete. Keep the house warm, check the readings the crew left, and watch the wet area for any change. A plumber's repair date should be set early, so the wall is not left open longer than it must be.
Keep the plumber's invoice, the crew's readings and the photographs of the split together. That record is what the insurer and any later buyer will want to see.
- Keep the house warm while the wall is open
- Check the readings the crew left on each day
- Watch the wet area for any new change
- Set the plumber's repair date early
- Keep the invoice, readings and photographs together
Frequently asked questions
What is the first thing to do if a line splits?
Shut off the water at the main or the nearest valve, open a tap and call a plumber and the 24/7 line.
Should I leave a tap dripping?
Yes, on a line that runs in an outside wall during a hard freeze. Moving water is less likely to freeze.
Can I use a heater on a frozen line?
Only a hair dryer or heated air, applied slowly. Never use an open flame.
Does the crew fix the split?
No. A plumber fixes the line. The crew finds the wet area and dries the structure, then writes the list for the plumber.
Is a freeze split covered by a policy?
That depends on the policy and the circumstances. Ask the insurer in writing which terms apply.
How often should I review this checklist?
Each autumn and after any split, because the house and its lines change over time.
Sources
This guide is general information for Milwaukee County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.