Help for Thornton homes with a frozen or thawed supply line, covering the wet aftermath, drying and what to check before the next cold snap.
Fastest: call (833) 490-5225. Or send this and we call you back.
A frozen line damages a building twice: ice can split the pipe, and the water arrives when the thaw restores pressure. The work is to catch it at the thaw, dry what got wet and find the cold spot that caused it. Thornton sits in a freeze window from about early October to early May.
If a tap has gone dry in cold weather and you suspect ice, the useful move is to open the nearest faucet on that line and close the main. An open faucet gives the thaw somewhere to go. Closing the main means that if the pipe has already split, the thaw does not arrive as a pressurized discharge into a wall while you are out looking for a heater.
The damage from freezing is rarely done when the pipe is frozen. Ice expanding in a confined section can fracture copper or stress a fitting, and nothing comes out while the plug is still solid. Hours later, when the sun hits a wall or the heat gets into a crawl space, the ice retreats and the water follows it through the fracture. That is why the quiet day after a hard night produces so many calls.
Where ice forms is predictable enough to inspect. Lines in unheated garages, crawl spaces, attics and exterior walls, hose bibs with the hose still attached, irrigation backflow assemblies and plumbing running past an air leak or a missing section of insulation are the usual places. Once the wet work is done, a technician will walk those with you, because the second freeze in the same spot is the one that is avoidable.
Any time the plumbing's surroundings are below freezing, which in this area runs from roughly early October to early May. National Weather Service figures reported locally put the average Denver first freeze in early October and the average last freeze in early May, and individual years have gone well outside that.
The outer edges of the record are the useful part. Reported figures give an earliest first freeze in early September and a latest spring freeze in early June of 2007, so a mild April is not a guarantee that outdoor plumbing can be left live. Equally, the deep events are not spread evenly through the season.
The extreme case is worth remembering when judging risk. On 22 December 2022 the National Weather Service recorded a Denver low of 24 degrees below zero, a single degree above the all-time December low, with the airport reportedly falling 37 degrees in one hour the previous day. A drop at that speed finds any line without insulation or a heat path.
Sometimes, with heat applied gently and the main closed first. Warm the area with a hair dryer or a space heater at a safe distance, keep the nearest faucet open, and work from the end nearest the tap. Never use a torch, and never leave a heat source unattended near framing or insulation.
The reason to close the main first is simple: you cannot tell from outside whether the ice has already split the pipe, and if it has, your successful thaw is also the start of the flood. With the main closed and a faucet open, a thaw that reveals a fracture produces a drip you can see rather than a discharge into a wall.
Know when to stop. If the frozen section is inside a wall or a ceiling, if the pipe is visibly deformed, or if the line will not run after reasonable warming, that is a plumber's job rather than a longer attempt with a bigger heater.
How long the water ran after the thaw, where the pipe was, how much insulation and material got soaked, whether a crawl space or cavity is involved, and the number of drying days the readings call for. The estimate is explained and you approve it before work starts.
Location does more to the price here than volume. A split in an open garage ceiling that was caught in the first hour is a modest job; the same split above a finished basement ceiling, discovered the next day, involves ceiling removal, insulation, cavity drying and a rebuild. Crawl spaces are slower again because of access and temperature.
Discovery time is the factor homeowners can influence. Walking the cold spaces after a hard night and knowing where the main is costs nothing and changes the scope substantially. The Thornton cost guide walks through the drivers, and no figures are published because no publishable local source gives them.
It may be, depending on the cause and your policy. The Colorado Division of Insurance says sudden plumbing failures may be covered, and insurers look at whether reasonable care was taken, such as keeping heat on in an occupied building. Your insurer decides, not the crew on site.
Keep evidence that supports the sudden nature of the loss. Photograph the split section, the wet area and the thermostat if the building was heated, and note when you discovered it. Keep the removed piece of pipe if a plumber replaces it, and keep the moisture log and material list from the drying.
On the process side, the Division's guidance says you can request the full policy and be given it within three business days, and that a denial has to be explained in writing. The Division reviews how claims are handled rather than deciding coverage, and takes complaints through its consumer portal at doi.colorado.gov. Our frozen pipes guide for Thornton covers the seasonal side in more detail.
Disconnect hoses and shut the interior valves feeding hose bibs, drain or blow out irrigation, insulate exposed runs in garages and crawl spaces, close crawl space vents in winter, and keep cabinet doors open on plumbing in exterior walls during a hard freeze. Know where the main valve is.
Autumn is the sensible time to do the lot, before the ground freezes and the first real cold arrives. The same walk-through also catches the things that cause basement water later in the year: downspouts discharging at the wall, a window well with no cover, a sump that has not been tested.
If you are leaving the house for a stretch in winter, keep the heat on, ask someone to look in, and consider closing the main. Call (833) 490-5225 if a line has already frozen and you would rather have someone watching the thaw with you than find out afterward.
Never thaw a pipe with a torch, a propane heater or any open flame: it is the most common cause of fires that start as plumbing problems, and it can boil water inside a closed section. Do not leave an electric heater running unattended against framing, insulation or cardboard. Keep the main closed until you know whether the line split, and do not restore pressure to a system that was frozen until a plumber has checked it. Stay out of standing water in a garage or basement where the panel, the furnace or the water heater sits in it. If a crawl space has water in it, do not crawl in to look.
Where a line is still frozen, the priority is to stop the thaw turning into a discharge: main closed, the affected faucet open, and someone watching the area where the pipe runs. The technician also looks at whether the suspect section can be reached at all without opening finished work. This is the one stage where waiting in the right place is the useful action.
Once water moves again the line is watched under pressure, with readings taken on the surrounding drywall, framing and floor. Some frozen sections thaw intact. Others leak only at full pressure, which is why a technician checks the wall and ceiling nearby rather than accepting that the tap runs again as proof of a happy ending.
Water from a thawed split is clean when it leaves the pipe, so prompt work saves materials. It is extracted, wet batt insulation comes out of affected bays, and drywall is cut back where the meter shows wicking. Everything removed is photographed and listed before it goes.
Freeze damage usually happens in the least convenient parts of a building, so drying frequently involves a crawl space, a garage ceiling or an exterior wall cavity rather than a tidy living room. Those spaces are colder, and cold air holds less moisture, so equipment selection and placement matter more than in a warm interior room. Readings are repeated at the same points until they match a dry reference.
The repair goes to a plumber, licensed by the state through the Department of Regulatory Agencies and verifiable on its online lookup. The cold spot gets attention too: insulation in the bay, the air leak that chilled it, a vent left open, or a hose bib and irrigation line that need shutting off from inside before winter. Rebuild work needing a building permit requires a contractor licensed with the City of Thornton.
The most common freeze point on a house here, and the easiest to prevent. A hose left attached traps water in the bib, and an irrigation line or backflow assembly that was not drained holds water all winter. These often leak into a crawl space, a garage or the wall behind the fitting rather than into the open, and the discovery can wait until the system is pressurized in spring.
Plumbing in a vented crawl space or an unheated garage is only as warm as that space, which in deep cold is not warm at all. A failure here can run for a long time with nobody above hearing it, soaking insulation, subfloor and framing. Drying a crawl space is slower work than drying a room, and it is where a thorough moisture map earns its keep.
A line run in an outside wall, particularly behind a kitchen sink cabinet or in a bathroom on the windward face, freezes when cold air gets into the bay through a gap in insulation or air sealing. The tell is a tap that goes dry only on the coldest nights. Correcting it is usually an insulation and air-sealing job rather than a plumbing one.
A vacant house, a rental between tenants, an unheated basement area or a commercial unit on a setback thermostat can lose enough heat for lines to freeze while the thermostat reading still looks acceptable. These produce the longest discharges, because nobody is there when the thaw comes. Keeping the heat up and the supply closed is the cheap insurance for a property standing empty in winter.
If it's an emergency, call now. For non-urgent frozen pipe damage repair, send the form and we'll call you back.
The local building pattern puts plumbing in cold places more often than people assume. With most homes here dating from the 1970s onward and a heavy 1990s-to-2000s share, the typical layout has attached garages, vented crawl spaces under additions, hose bibs on two or three elevations and irrigation serving a lawn, and each of those is a run of pipe living outside the heated envelope for seven months of the year. The freeze calls cluster on those lines rather than on the plumbing in the middle of the house.
The season has a shape worth planning around. The freeze-risk window for supply lines runs from about early October to early May, with the average Denver first and last freeze dates sitting at either end of it according to National Weather Service figures reported locally. Deep cold arrives inside that window rather than throughout it, and the single hardest recent example, the 24-below Denver low on 22 December 2022, produced the kind of overnight event that leaves a whole metro's worth of garages and crawl spaces to check the next morning.
Freeze damage and ground damage overlap here in a way they do not everywhere. Expansive soils run the length of the Front Range, and the Colorado Geological Survey connects differential heave in them to structural damage, so water released under a slab or beside a footing in winter is doing two things at once. That is one reason a technician drying a crawl space after a freeze also looks at where the water went in the soil, not only at the wet joists overhead.
Cleanup and drying after a pressurized line fails in a Thornton home or building, including water that travelled inside walls and floors.
Pumping out, clearing and drying a crawl space after a plumbing leak, seepage or storm water collects under the floor.
Tracing and drying water damage from a pressurized supply line leaking inside a wall, floor or ceiling cavity.
Meter readings, extraction and monitored drying for Thornton homes and shops, with a written record for your insurer and an estimate approved before work starts.
Not sure if you're covered? Check your ZIP code.
Shut the water off at the main the moment you suspect a burst, then open a faucet to relieve pressure.
Not necessarily, which is the awkward thing about freeze damage. A thawed line can run normally and still leak at a fracture only under full pressure, or leak into a cavity where nothing shows for a day. Check the walls, ceilings and floor near the run, and if any surface reads damp or smells damp, have it looked at before you forget about it.
Moving water is harder to freeze than still water, so a slow drip on a run you know is vulnerable can help on a hard night. It is a stopgap rather than a fix: the real answer is insulation, air sealing and shutting off whatever serves the outdoors. Leaving a tap running for weeks is not a plan.
Because an attached garage is usually outside the insulated envelope, so it tracks outdoor temperature far more closely than any room. A line running through a garage ceiling or along its wall can be well below freezing while the thermostat inside reads comfortable. The same applies to vented crawl spaces and unconditioned attics.
Often you do not until it is pressurized in spring, which is why the first start-up of the season is worth watching rather than switching on and walking away. Look for water at the backflow assembly, at valve boxes and inside the wall or crawl space the line passes through, and listen for water running when no zone is active.
Sometimes, if the failed section is accessible from a crawl space, basement or soffit. Where it is inside a finished wall or ceiling, access has to be made, and it is better to make one opening where the readings and the plumbing layout point than several exploratory ones. Every opening is explained and photographed first.
Closing them during the cold months is a common approach for keeping plumbing above freezing, with the proviso that the space needs managing for moisture rather than simply being sealed and forgotten. Ask a plumber or a contractor about your particular crawl space, since the plumbing, the insulation and any ductwork down there all affect the right answer.
A vacant building is the highest-risk case, because a freeze and a thaw can both happen with nobody present. Keep the heat on rather than off, close the main if the water is not needed, and have someone check inside during cold spells. If it will be empty through the winter, ask a plumber about draining the system properly.