Key Takeaways
- Boise winters regularly drop below 20°F, putting exposed and poorly insulated pipes at serious risk of freezing.
- Pipes in crawl spaces, exterior walls, and unheated garages freeze first—insulating them is the single most effective prevention step.
- If your pipes do freeze, never use an open flame to thaw them. Use a hair dryer, heat lamp, or call a professional.
- Frozen pipe bursts cause an average of $5,000–$10,000 in water damage per incident.
Every winter, frozen pipes are one of the most common—and most expensive—plumbing emergencies in Boise, Idaho. With average January lows dipping into the low 20s°F and cold snaps pushing temperatures well below zero, Boise homeowners need to take pipe freezing seriously. This guide covers everything you need to know: which pipes are most vulnerable, proven prevention methods, and exactly what to do if your pipes freeze this winter.
Why Frozen Pipes Are a Serious Risk in Boise
Boise’s climate creates perfect conditions for frozen pipes. The city experiences an average of 45–50 nights per winter below 32°F, with the coldest stretches in December and January often bringing lows of 10–15°F. During arctic cold snaps—which hit the Treasure Valley every few years—temperatures can plunge below 0°F.
When water inside a pipe freezes, it expands by approximately 9%. This expansion creates enormous pressure—up to 2,000 PSI—against the pipe walls. The pipe doesn’t necessarily burst at the ice blockage. Instead, pressure builds between the frozen section and a closed faucet, causing the pipe to fail at its weakest point. The result is a crack or split that can release hundreds of gallons of water per hour once the ice thaws.
Which Pipes Freeze First in Boise Homes
Not all pipes are equally vulnerable. In Boise homes, these locations are at highest risk:
Crawl Spaces
Many Boise homes—especially older homes in the North End and Hyde Park neighborhoods—are built on raised foundations with crawl spaces. Water supply lines running through uninsulated or poorly sealed crawl spaces are extremely vulnerable to freezing. Vents that allow outside air into the crawl space accelerate cooling.
Exterior Walls
Pipes running through exterior walls (common for kitchen sinks on outside walls and bathroom supply lines) have less insulation between them and freezing outdoor temperatures. Older Boise homes often have minimal wall insulation by modern standards.
Unheated Garages
If water supply lines pass through your garage—common in Boise homes where the laundry room shares a wall with the garage—these pipes are at high risk. Garages are typically unheated and poorly insulated.
Outdoor Faucets and Hose Bibs
Outdoor faucets (hose bibs) that haven’t been properly winterized are among the first casualties of a freeze. A frozen hose bib can crack the pipe behind the wall, causing water damage inside your home.
Attic and Ceiling Spaces
Some Boise homes have water lines running through attic spaces, particularly for upstairs bathrooms. These pipes are surrounded by cold air and can freeze quickly during cold snaps.
How to Prevent Frozen Pipes: Step-by-Step
1. Insulate Vulnerable Pipes
This is the single most effective prevention measure. Use foam pipe insulation (available at any Boise hardware store for $3–$8 per 6-foot section) on all exposed pipes in crawl spaces, garages, attics, and exterior walls. For high-risk areas, use heat-trace cable wrapped around the pipe under the insulation—these electric cables maintain pipe temperature above freezing and cost $30–$80 per section.
2. Seal Crawl Space Vents
During winter, close or cover crawl space vents to prevent cold air from circulating under your home. Foam vent covers are inexpensive and effective. For homes with serious crawl space cold issues, consider a full encapsulation (vapor barrier + insulation), which also helps with energy efficiency.
3. Open Cabinet Doors
On especially cold nights (below 20°F), open cabinet doors under kitchen and bathroom sinks on exterior walls. This allows warm air from your home to reach the pipes. If you have small children, temporarily move any household chemicals to a higher location.
4. Let Faucets Drip
When temperatures drop below 20°F, let cold water drip from faucets served by exposed pipes. A slow drip—even a trickle—relieves pressure in the system and keeps water moving, making it harder to freeze. Yes, this wastes a small amount of water, but the cost is negligible compared to repairing a burst pipe.
5. Maintain Home Temperature
Keep your thermostat set to at least 55°F, even when you’re away or sleeping. The small increase in heating costs is far less expensive than frozen pipe repairs. If you’re traveling during winter, never turn your heat off entirely—set it to 55°F minimum.
6. Disconnect and Drain Outdoor Hoses
Before the first freeze (typically mid-to-late October in Boise), disconnect all garden hoses from outdoor faucets. Leaving a hose connected traps water in the hose bib, which will freeze and crack. After disconnecting, open the outdoor faucet briefly to drain residual water. If you have frost-free hose bibs, they still need hoses disconnected to function properly.
7. Winterize Irrigation Systems
Boise’s irrigation and sprinkler systems must be blown out before winter. Hire a landscaping or irrigation company to force compressed air through the system, clearing all water from the lines. This typically costs $50–$100 and prevents cracked sprinkler pipes and valves throughout your yard.
8. Know Your Main Water Shut-Off Location
If a pipe does burst, shutting off the water supply immediately limits damage. Know where your main shut-off valve is—in most Boise homes, it’s in the basement, crawl space, or near the water meter on the street side of the house. Test it now to make sure it turns easily.
What to Do If Your Pipes Freeze
If you turn on a faucet and only a trickle comes out—or nothing at all—during cold weather, you likely have a frozen pipe. Here’s what to do:
- Keep the faucet open. As you thaw the pipe, water needs somewhere to go. Running water through the pipe also helps melt remaining ice.
- Locate the frozen section. Feel along exposed pipes for sections that are extremely cold, bulging, or covered in frost.
- Apply gentle heat. Use a hair dryer, heat lamp, portable space heater (pointed at the pipe, not directly touching), or towels soaked in hot water. Work from the faucet end backward toward the frozen section.
- Never use an open flame. Propane torches, blowtorches, and charcoal stoves can ignite your home and cause pipe damage. This is a leading cause of house fires during cold snaps.
- Check other faucets. If one pipe is frozen, others may be too. Test all faucets in your home.
- Call a plumber if you can’t locate or reach the frozen section. If the frozen pipe is inside a wall, ceiling, or inaccessible area, you need a professional with the right tools. Call Hyde Park Plumbing’s 24-hour emergency line at (208) 994-3745.
Signs of a Frozen Pipe (Don’t Ignore These)
- No water from one or more faucets when temperatures are below freezing
- Reduced water pressure that worsens as temperatures drop
- Frost visible on an exposed pipe
- Bulging pipe—a pipe that looks swollen or distorted
- Strange odors from a drain or faucet (sewer gas can back up if drain lines freeze)
- Wet spots on walls or ceilings after a cold night—this may indicate a pipe has already burst inside a wall
Boise-Specific Winterizing Tips
Boise’s housing stock spans over 100 years, and different home types face different winter plumbing challenges:
North End and Hyde Park Homes (Pre-1950)
These older homes often have shallow crawl spaces, original galvanized pipes, and minimal insulation. Priority: insulate crawl space pipes, seal foundation vents, and consider a plumbing inspection to identify the most vulnerable sections.
Bench and Vista Homes (1950s–1980s)
Many Bench-area homes have slab foundations, which means water lines enter through or under the slab. While under-slab pipes are somewhat protected from freezing, pipes in exterior walls and garages are still at risk. Priority: insulate garage pipes and check exterior wall insulation.
Southeast Boise and Newer Subdivisions (Post-2000)
Newer homes generally have better insulation and PEX plumbing (which is more freeze-resistant than copper or galvanized steel). However, PEX can still burst under extreme pressure. Priority: insulate any pipes in the garage, attic, or exterior walls, and make sure crawl space vents have covers.
Cost of Frozen Pipe Repairs in Boise
The cost of frozen pipe damage depends on whether the pipe actually bursts:
- Thawing a frozen pipe (no damage): $100–$300 for a plumber visit
- Repairing a burst pipe (accessible location): $200–$500
- Repairing a burst pipe inside a wall: $500–$1,500 (includes drywall repair)
- Water damage restoration: $2,000–$10,000+ depending on severity
Insurance typically covers sudden burst pipe damage but not damage from gradual leaks or failure to maintain your home. Prevention is always more cost-effective than repair.
Frequently Asked Questions
At what temperature do pipes freeze in Boise?
Pipes are at risk of freezing when outdoor temperatures drop below 20°F, especially if they’re in unheated or poorly insulated areas. However, pipes in crawl spaces or exterior walls can freeze at temperatures as high as 28°F if there’s wind or inadequate insulation. In Boise, the highest risk periods are December through February.
Will my homeowner’s insurance cover frozen pipe damage?
Most homeowner’s insurance policies in Idaho cover damage from sudden pipe bursts, including water damage to your home and belongings. However, insurance typically does not cover the pipe repair itself, damage from gradual leaks, or damage that results from negligence (such as leaving your home unheated during winter). Review your policy and contact your agent with specific questions.
Can PEX pipes freeze and burst?
PEX (cross-linked polyethylene) pipe is more freeze-resistant than copper or galvanized steel because it can expand slightly. However, PEX can still burst under extreme pressure from ice expansion. PEX fittings and connections are often the weak point that fails first. Don’t assume PEX pipes are immune to freezing—insulate them just like any other pipe material.
Should I leave my heat on if I’m traveling in winter?
Absolutely. Never turn off your heating system entirely during Boise winters. Set your thermostat to at least 55°F while you’re away. Consider asking a neighbor or friend to check your home daily during cold snaps. Some homeowners install smart thermostats with freeze alerts that notify you via smartphone if indoor temperatures drop dangerously low.
Don’t wait for a pipe to burst. If you need help winterizing your plumbing or you’re dealing with a frozen pipe emergency, call Hyde Park Plumbing at (208) 994-3745. We offer 24-hour emergency service throughout the Boise metro area and can help protect your home from winter plumbing damage.