Short answer: attic pipes freeze because Texas attics are unconditioned and the plumbing in them is usually uninsulated. Insulating the pipes and improving attic insulation are the two preventive fixes, and knowing where your main shutoff is matters more than anything else during the event.
This is not strictly roofing, but it lives in the attic, the damage lands on your ceilings, and it is the question we get most during a cold snap. So here it is.
Why Texas has this problem and northern states do not
In cold climates, plumbing is routed through conditioned interior spaces, or it is heavily insulated, because freezing is a known design constraint. In Texas, builders ran supply lines through attics for decades because it is cheap, convenient and the risk seemed theoretical.
It is not theoretical. Uri demonstrated that at scale across the Hill Country and San Antonio in 2021, and the failure pattern repeats in smaller events.
What actually happens
Water expands as it freezes. In a closed pipe that expansion has nowhere to go, so pressure builds between the ice plug and a closed faucet until something splits. The split usually does not leak immediately. It leaks on the thaw, often while nobody is home, and the water lands on the ceiling below.
The connection to your roof and attic
- Attic insulation depth determines how cold your attic actually gets relative to outside. A well insulated ceiling plane keeps house heat in the house, which is good for your bill but means the attic runs colder. The answer is insulating the pipes themselves, not under insulating the ceiling.
- Air leaks around soffits, gable vents and roof penetrations let cold outside air wash directly over pipe runs.
- Pipes in exterior walls and along the eaves are the first to go, because that is where cold concentrates.
Before a freeze
- Insulate attic plumbing. Foam pipe sleeves are inexpensive and available at any hardware store. Cover every accessible run, especially near eaves and exterior walls.
- Know where your main shutoff is and make sure it turns. Test it now, not in the dark during a storm.
- Seal air leaks that blow cold air across pipe runs.
- Disconnect and drain hose bibs and cover exterior spigots.
- Get insulation to proper depth while you are up there anyway.
During a hard freeze
- Drip faucets on the coldest runs. Moving water resists freezing and a dripping tap relieves pressure buildup.
- Open cabinet doors under sinks on exterior walls.
- Leave the attic hatch cracked open if a hard freeze is forecast. Letting a little house heat into the attic is the cheapest emergency measure available.
- Keep the heat on even if you leave town. Setting it to 50 is far cheaper than a burst pipe.
- If you lose power, consider shutting off the main and draining the system.
If a pipe bursts
- Shut off the main immediately
- Kill power to affected circuits if water is near fixtures or outlets
- Contain what you can and move belongings
- If a ceiling is bulging with trapped water, a relief hole over a container prevents a larger collapse
- Photograph everything before cleanup for the claim
- Call a plumber for the pipe, and get the ceiling and attic assessed afterward
Where we come in
After a burst pipe, someone needs to look at what the water did on the way through: wet insulation that needs replacing, decking that got soaked, and whether the attic conditions that let it freeze can be improved before next winter.
That assessment is free. Get in touch or call (210) 245-4125, and see our freeze prep guide for the roof side.
