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Frozen Pipe Prevention for Montana Homes: What to Do Before the First Deep Freeze

Frozen pipe prevention for Montana homes: where pipes freeze, what insulation and heat cable cost, thermostat and drip rules, and what to do if one freezes.

Frozen Pipe Prevention for Montana Homes: What to Do Before the First Deep Freeze

Montana plumbers see the same pattern every year. The first stretch of nights below zero, usually in late November or December along the Hi-Line and in the mountain valleys, brings a wave of calls about pipes that froze in crawl spaces, garages, and exterior walls.

The repair for a single burst pipe runs $400 to $1,500 in 2026, and the water damage that follows can run into the tens of thousands. Most of it is preventable with a few hours of work in October.

The state's cold is different from what people in milder places prepare for. Great Falls, Havre, and Cut Bank see stretches of 20 below with wind, and Bozeman, Butte, and Missoula get long spells in the single digits. A pipe that would survive a Denver winter in an exterior wall does not survive a Montana one, and the difference between a pipe that freezes and one that does not often comes down to a $10 piece of foam or a heat cable installed before the cold arrives.

Where Montana Pipes Freeze

Crawl spaces are the most common failure point in the state. Older homes in Billings, Great Falls, and Helena often have vented crawl spaces with supply lines running along the floor joists, and once the vents let in subzero air the pipes are exposed. Closing the vents in fall, insulating the pipes, and making sure the crawl space stays above freezing solves most of these.

Exterior walls are second. Kitchens and bathrooms built on an outside wall, common in ranch homes from the 1960s and 1970s, have supply lines with only a few inches of insulation between them and the weather.

When the wind hits that wall at 20 below, the pipe inside can freeze even with the furnace running. Opening the cabinet doors and letting a faucet drip on the coldest nights is the standard fix, and adding insulation inside the wall is the permanent one.

Garages, unheated additions, and mudrooms round out the list. A water line to a utility sink in an unheated garage in Kalispell or a hose bib that was not shut off in a Bozeman subdivision will freeze the first cold week. The same goes for well pump houses and the supply lines running from a well to the house on rural properties.

Hose Bibs and Irrigation

Outdoor spigots are the easiest thing to protect and the most commonly forgotten. Shut the interior valve, open the exterior spigot to drain it, and leave it open through the winter.

Frost-free hose bibs help but still need the hose disconnected, because a hose left attached traps water in the valve body. Irrigation systems need a full blowout with compressed air, which costs $60 to $150 from a landscaping or plumbing company and should be done by mid-October in most of the state.

Insulation and Heat Cable

Foam pipe insulation costs about $1 to $3 per foot and is the first line of defense for any exposed pipe in a crawl space, garage, or basement. It slows heat loss but does not add heat, so in a space that drops well below freezing it buys time rather than solving the problem.

For a crawl space that stays in the 20s, foam is often enough. For a garage that hits zero, it is not.

Heat cable, also called heat tape, is the answer for pipes that sit in cold spaces. Self-regulating heat cable costs $2 to $5 per foot and plugs into an outlet, warming the pipe only when the temperature drops.

Installed by a plumber or electrician, a 20-foot run on a crawl space supply line costs $150 to $400. It uses very little power and has kept thousands of Montana pipes from freezing.

Wrapping the cable and then adding foam insulation over it is the standard method. Do not use foam over a cable that is not rated for it, and do not overlap or cross the cable on itself. Old-style constant-wattage heat tape from decades ago is a fire risk when it is aged and should be replaced.

Crawl Space Vents and Insulation

Montana crawl spaces with open foundation vents should have the vents closed and covered from October through April. A foam vent cover costs a few dollars.

Insulating the crawl space walls with rigid foam, rather than the floor above, keeps the whole space closer to house temperature and is the approach most energy auditors in the state recommend now. That project runs $1,500 to $4,000 for a typical home and pays off in both frozen pipe prevention and heating bills.

Thermostats, Drips, and Leaving Town

Keep the house at 55 degrees or above when you are away, even for a weekend. The savings from setting the thermostat to 45 are small, and a furnace failure while you are gone leaves the house at outdoor temperature within hours. Many Montana homeowners add a wifi thermostat or a temperature sensor that texts them if the house drops below 50, which costs $50 to $250 and has saved a lot of pipes.

On the coldest nights, let the faucet on the most exposed line drip. Moving water freezes much more slowly than still water, and a pencil-thin stream from a kitchen faucet on an outside wall costs a few cents a night. Open the cabinet doors under sinks on exterior walls so room air reaches the pipes.

For a house that will sit empty for weeks, the best protection is to shut off the main and drain the system. A plumber can winterize a home for $150 to $400, which includes draining the supply lines, adding antifreeze to traps and the toilet, and shutting down the water heater. Snowbirds leaving Montana for the winter should do this rather than trust the furnace to run for four months unattended.

Well Systems and Pressure Tanks

Rural homes on wells have an extra set of exposures. The pump house or the well pit needs a heat source, usually a heat lamp or a small thermostatically controlled heater, and the line from the well to the house should be below frost depth.

Frost depth in much of Montana is four to six feet, and older lines that were buried shallow freeze in a hard winter. Rerouting or deepening a well line costs $2,000 to $6,000 and is a summer project, not a November one.

What to Do If a Pipe Freezes

Shut off the main water valve first, before you do anything else. A frozen pipe has not necessarily burst, and the damage happens when it thaws and water starts flowing through a crack. Open the faucet served by the frozen line so pressure can escape and so you know when it thaws.

Warm the pipe slowly with a hair dryer, a heat gun on low, or towels soaked in hot water, working from the faucet end back toward the frozen section. Never use a torch or open flame. If you cannot find or reach the frozen section, or if the pipe is inside a wall, call a plumber, because most Montana companies have thawing equipment that can heat a pipe through drywall.

A plumber's emergency thaw call runs $200 to $500 in Montana. A repair on a burst copper or PEX line costs $400 to $1,500 depending on access, and a pipe that burst inside a finished wall costs $1,500 to $5,000 once drywall and paint are included. Finding plumbers who serve your part of Montana before the cold arrives means you have a number to call when a pipe freezes at 2 a.m. and the phone lines are busy.

A Fall Checklist for Montana Homeowners

Walk the house in October and find every pipe that runs through an unheated space. Crawl spaces, garages, attics with plumbing, and exterior walls with kitchen or bath fixtures are the places to look. Insulate what can be insulated and add heat cable where insulation alone will not hold.

Shut off and drain every hose bib, blow out the irrigation system, and cover the crawl space vents. Confirm the furnace has been serviced and the filter is clean, because a furnace failure on a cold night is the fastest way to freeze every pipe in the house at once. Test the sump pump if you have one.

Set the thermostat to hold 55 or higher when the house is empty and consider a temperature alarm. If you will be gone for more than a couple of weeks, have the house winterized. Our blog has more seasonal home maintenance guides for Montana if you are working through the rest of the fall list.

Frequently Asked Questions

At what temperature do pipes freeze in Montana homes?

Exposed pipes can freeze when the surrounding air drops below about 20 degrees for several hours, and in a crawl space or garage that happens on most December nights across the state. Pipes inside heated walls usually hold until outdoor temperatures drop below zero with wind.

Does heat tape use a lot of electricity?

No. Self-regulating heat cable draws roughly 3 to 6 watts per foot only when it is cold, so a 20-foot run costs a few dollars a month during the coldest stretch. Constant-wattage tape uses more and should be replaced if it is old.

Should I leave faucets dripping all winter?

Only on the coldest nights and only on lines in exposed locations. A steady drip all winter wastes water and money. Insulation and heat cable are the long-term answer for a pipe that needs a drip to survive.

How much does it cost to winterize a house in Montana?

$150 to $400 for a plumber to drain the supply lines, add antifreeze to traps, and shut down the water heater. It is the right choice for a home that will sit empty for more than a couple of weeks in winter.

Will homeowners insurance cover a burst pipe?

Most policies cover sudden water damage from a burst pipe, but many exclude damage if the home was left unheated or unoccupied without reasonable precautions. Keeping the heat at 55 and having the house winterized protects the claim as well as the pipes.