Which pipes are most likely to freeze?
Short answer: The pipes most likely to freeze are those outside the heated envelope or at its edge: exterior hose bibs, lines in unheated garages, crawl space and rim joist runs, attic plumbing, supply lines in exterior walls, and pipes in unheated additions or vacant units. Within a home, the kitchen sink on an outside wall and the fixture farthest from the furnace are typical first failures.
Need this handled today?
Call for emergency response in Denver and the surrounding metro.
Call Now for Emergency Help(720) 319-807324/7 Emergency Call HandlingKey Takeaways
- Hose bibs with a hose still attached are the most common single failure point.
- Attic runs are the most damaging, because water travels down through two levels.
- Crawl space and rim joist plumbing freeze early when vents are open or air sealing is poor.
- Kitchen sinks on exterior walls freeze more often than bathroom sinks on interior walls.
- Unused lines, like a basement utility sink, freeze without anyone noticing.
Ranked by Risk
- Exterior hose bibs and irrigation backflow devices.
- Unheated garage supply lines and garage utility sinks.
- Crawl space and rim joist runs.
- Attic plumbing, including second-floor bathroom lines and refrigerator supply.
- Exterior wall plumbing, especially kitchen sinks and wet bars.
- Unheated additions, sunrooms, and converted porches.
- Vacant units, seasonal properties, and rooms with heat turned off.
Why Location Beats Material
Pipe material affects whether a freeze causes a split, but location determines whether a freeze happens at all. A well-insulated copper line inside a heated wall rarely freezes, while an uninsulated PEX line in a vented crawl space freezes every cold snap. Address the space before worrying about the pipe.
Protecting Each Location
- Hose bibs: disconnect hoses, install frost-proof bibs, use insulated covers.
- Garage: insulate the run, keep the door closed, add a small thermostatically controlled heater if needed.
- Crawl space: air-seal, insulate pipes and rim joists, close vents seasonally per your foundation design.
- Attic: insulate pipes heavily and verify air sealing at the ceiling plane.
- Exterior walls: open cabinets, drip the fixture, and consider rerouting during any remodel.
Colorado and Denver Considerations
Many Front Range homes built before the 1980s have plumbing in uninsulated exterior walls and vented crawl spaces. Those two conditions account for a large share of Denver metro freeze losses, and both are addressable during any remodel or insulation upgrade.
Exceptions and Important Considerations
- A south-facing wall with sun exposure may survive conditions that split a north wall line.
- Homes with hydronic heat can have baseboard loops in cold spaces that freeze and damage floors.
- Multifamily buildings can freeze a shared riser, affecting many units at once.
Related Questions
Prioritize pipes outside conditioned space. Insulating interior lines that never freeze offers little benefit.
Thermostatically controlled, UL listed heat cable installed per instructions is safe. Old or improvised heat tape is a fire risk.
Almost always cold air infiltration at a rim joist or a wall penetration near the pipe.
Classic risk. Open the cabinet doors on cold nights and drip the faucet during hard freezes.
Burst and Frozen Pipe Damage in Denver
Call (720) 319-8073 for 24/7 emergency response across Denver metro.