A tap that has slowed to a trickle in cold weather
The earliest warning available and the best moment to act. Partial freezing is far easier to resolve than a fully blocked run.
The damage happens when it thaws
Frozen Pipe Repair in Acres Green, CO
- Isolation before thawing
- Answered through the coldest nights
- Pressure tested after thaw
- Prevention addressed, not just the repair
A frozen pipe is not yet a flood. It becomes one at the moment the ice releases, because the expansion that occurred while freezing has usually already split the pipe, and nothing comes out of a split until flow returns.
That sequence is why the first instruction on any frozen pipe call is to isolate the run rather than to start warming it. Thawing an unisolated pipe that has already split converts a contained problem into water running through a building with nobody in position to stop it.
Response, repair and prevention
01 02 03 04 05 06 07
There are three distinct pieces of work here and they happen in a fixed order. Containing the immediate risk, restoring the supply safely, and then addressing why that particular run froze in the first place.
The third piece is the one most often skipped, and it is why the same pipe in the same house freezes in successive winters. Pipes do not freeze randomly. They freeze where they are exposed, and that exposure is usually fixable.
What to do before anybody arrives
Close the isolation valve serving the affected run if you can identify it, or the main stop if you cannot. This is the single most valuable action available and it costs nothing. A split that releases into an isolated run puts out the water already in the pipe and stops. The same split on a live main runs until somebody finds the valve.
Open a tap on the affected run, downstream of the freeze. This relieves pressure and gives any meltwater somewhere to go as thawing begins, and it also tells you the moment flow returns.
Do not apply a naked flame under any circumstances. Torches on frozen pipework cause structure fires every winter, they can produce steam pressure in a sealed section violently, and on plastic pipe they destroy the pipe outright. Warm air, heat tape and warm cloths are the appropriate tools.
If water is already escaping, close the main immediately and then deal with electrical safety. Water travelling through a building reaches ceiling fixtures and wiring, and switching off the affected circuits is a genuine priority rather than a precaution.
Controlled thawing and what follows it
Thawing is done gradually and from the open end back toward the freeze, so that meltwater has a route out rather than being trapped between two ice plugs. Heating the middle of a frozen section first is how a pipe gets burst by the thawing itself.
Access is frequently the difficulty. Pipes freeze in the places that are cold, which are also the places that are hard to reach: crawl spaces, exterior wall cavities, unheated garages, attics and beneath cantilevered floors. Sometimes warming the space is the only practical approach and it is slower than everyone would like.
Once flow returns, the run is pressure tested rather than declared repaired. Splits are often small, and a pipe that has been stretched may seep rather than spray. Copper tends to split along its length. Plastic piping systems generally tolerate freezing better but fittings and joints remain vulnerable. Any section that shows deformation is replaced rather than left in service, because a stretched pipe has already lost wall thickness.
Repairs are made in the correct material with proper joints, and the section is tested again before the work is closed up. Where a run has frozen once, the repair is also the moment to decide whether it should stay where it is.
Why that run froze, and how to stop it recurring
Freezing requires a pipe to be in a location that falls below freezing with insufficient heat reaching it. The remedies follow directly from that.
Insulation is the first and cheapest, and it is frequently misunderstood. Pipe insulation slows heat loss, it does not generate heat, so it delays freezing rather than preventing it indefinitely. On a run with some warmth reaching it, insulation is often enough. On a run in a genuinely unheated space during a prolonged freeze, insulation alone will eventually fail.
Heat tape or trace heating adds the heat that insulation preserves, and on exposed runs that cannot be moved it is the reliable answer. It needs a proper electrical supply and it should be the thermostatically controlled type rather than a length left permanently energized.
Air sealing matters more than people expect. A small gap admitting outside air directly onto a pipe in a wall cavity will freeze that pipe while the rest of the run is fine. Rim joists, utility penetrations and sill plates are the usual locations, and sealing them is inexpensive.
Rerouting is the permanent answer where a run passes through an exterior wall or an unheated space and does not need to. Moving it into conditioned space removes the problem entirely rather than managing it, and it is frequently more practical than households assume.
Unoccupied and seasonal properties
The worst frozen pipe damage happens in buildings with nobody in them, because the water runs for days rather than minutes. Rental voids, properties for sale, second homes and commercial units between tenants are all high risk, and all of them are preventable.
Where a property will be unoccupied through cold weather, the reliable approach is to isolate the supply at the main and drain the system down, including traps, so there is no water left to freeze. That is more thorough than leaving the heating on low, which depends on a boiler continuing to work, a fuel supply continuing, and the electricity staying on.
Where the building must stay heated, a low temperature alert is the minimum sensible precaution. A remote monitoring thermostat that notifies when internal temperature falls below a threshold costs very little and provides the warning that turns a catastrophe into a phone call.
For landlords and managers, having the main stop valve location recorded and accessible, and known to whoever might be first on site, is worth more on the night than any amount of insulation. A great deal of damage is done in the time it takes somebody unfamiliar with a building to find the valve.
Vulnerable locations and the appropriate remedy
| Location | Why it freezes | Remedy |
|---|---|---|
| Exterior wall cavity | Little or no heat reaches the run | Reroute where possible, otherwise insulate and air seal |
| Unheated crawl space | Ambient falls below freezing | Insulation plus heat tape, and seal vents seasonally |
| Attached garage | Regularly below freezing when the door opens | Insulate, heat tape, or reroute |
| Attic runs | Unheated space above the insulation line | Insulate heavily, or relocate below the ceiling |
| Under a cantilevered floor | Cold air on multiple sides | Air seal the cavity and insulate the run |
| Outside hose bibs | Directly exposed | Frost proof fittings, isolate and drain in autumn |
| Vacant property anywhere | No heat and nobody present | Drain down, or heat with a low temperature alert |
How the call is handled
01
Isolate first, over the phone
You are talked through closing the correct valve before anything else, because that is what limits the damage.
02
Assess the situation on arrival
Whether water has already escaped, which runs are affected, and whether electrical safety needs addressing first.
03
Thaw under control
Gradual warming from the open end back toward the freeze, with no naked flame at any point.
04
Pressure test and repair
Splits found by test rather than by waiting for them to show, with any deformed section replaced rather than left in service.
05
Address the cause
Insulation, heat tape, air sealing or rerouting, so the same run does not present the same problem next winter.
Warning signs and risk factors
One fixture dry while others work
Localises the freeze to a specific run immediately, which speeds everything that follows.
Visible frost or condensation on exposed pipework
The run is at or near freezing. It needs addressing before the next cold night rather than after.
A run that has frozen in a previous winter
It will freeze again. The conditions have not changed, and prevention work on that specific run is the cheapest money available.
A property that will be empty through winter
The highest risk situation there is, and the most completely preventable by draining down or monitoring.
Cold drafts in a crawl space or basement
Air movement carries heat away from pipework far faster than still cold air does.
Water pressure that dropped suddenly in freezing weather
Possibly a split that has already occurred elsewhere on the system. Worth investigating immediately rather than waiting.
Frozen pipe questions
What to Do, and What Not to Do
Worth reading before winter rather than during it.
Only after isolating the run, and only with safe methods. Warm air from a hairdryer or a space heater, warm cloths, or thermostatically controlled heat tape are all acceptable. Work from the open tap back toward the freeze so meltwater has somewhere to go. Never use a torch or any naked flame: it causes structure fires every winter, it can generate steam pressure violently in a sealed section, and on plastic pipe it destroys the pipe. And be ready at the valve, because if the pipe has split you will find out the moment flow returns.
Usually you do not until it thaws, which is exactly why isolation comes first. Visible bulging or deformation is a strong indicator, as is a section that feels distorted. Copper tends to split along its length rather than at a joint. Once thawed, the run is pressure tested rather than simply turned back on, because small splits seep rather than spray and can go unnoticed inside a wall for months while doing steady damage.
It helps and it is not a guarantee. Moving water freezes less readily than still water, and a slow trickle also relieves the pressure that builds between an ice plug and a closed tap, which is the pressure that actually splits pipes. It is a reasonable precaution on a known vulnerable run during a hard freeze. It is not a substitute for insulation, air sealing or rerouting, and it will not save a pipe in a genuinely unheated space through a prolonged cold spell.
No, and this is the most common misunderstanding about it. Insulation slows the rate of heat loss, so a pipe with some warmth reaching it stays above freezing much longer. A pipe in a space that is itself below freezing has no heat to preserve, and insulation only delays the inevitable. On genuinely cold runs the answer is heat tape to add heat, air sealing to stop cold air reaching the pipe, or rerouting to remove the exposure entirely.
Drain it down. Close the main, open every tap to empty the system, drain the water heater, and put antifreeze in traps so they do not freeze and crack. That removes the risk completely rather than managing it. Leaving the heating on low is the alternative and it depends on the boiler continuing to work, the fuel continuing and the power staying on, any of which can fail unattended. If you do leave it heated, fit a low temperature alert so somebody finds out early.
Frequently yes for sudden accidental damage, and frequently not where a property was left unoccupied and unheated without reasonable precautions. Policies vary considerably and many carry specific conditions about unoccupied buildings and minimum maintained temperatures. That is a question for your insurer rather than for us, and it is worth asking before winter rather than after a claim. What we can provide is documentation of the repair and the cause.
Also in the catalog
Related Cold Weather Work
Freeze events rarely involve only one part of a building's systems.
Isolate, then call
Frozen or Burst, Answered Through the Coldest Nights
Close the valve first. Everything after that is easier, and the difference between a contained problem and a flood is usually those few minutes.
Once the immediate situation is resolved, the run that froze gets addressed so the same night does not repeat next winter.
- Isolation talked through on the call before dispatch
- Controlled thawing with no naked flame at any point
- Pressure testing rather than assuming the pipe survived
- Deformed sections replaced rather than returned to service
- Insulation, heat tape, air sealing or rerouting as appropriate
- Drain down and monitoring advice for unoccupied properties