Every winter, homeowners across the country face one of the most common—and most expensive—cold-weather emergencies: frozen pipes. When temperatures plunge, plumbing systems become extremely vulnerable, and once a pipe freezes, the risk of it bursting skyrockets. What surprises most people is how quickly frozen pipes can lead to major water damage. A single burst pipe can release hundreds of gallons of water in minutes, flooding rooms, damaging flooring, and even causing long-term mold issues.
So what temperature causes pipes to freeze? How do you know if your pipes are already in danger? And what can you do right now to stop frozen pipes before they burst?
Below is the complete, homeowner-friendly guide you need this winter.
At What Temperature Do Pipes Freeze?
The Critical Temperature Homeowners Should Know
Most pipes begin freezing when the outside temperature drops to 20°F (-6°C) or below. This is the widely accepted threshold where enough heat has escaped from unprotected plumbing for ice to form inside the pipe.
However, pipes can freeze at temperatures higher than 20°F if:
They are located in uninsulated areas
They are exposed to wind
A cold front hits quickly
There is prolonged cold over multiple nights
Small, unprotected sections of pipe can freeze well before an entire plumbing system is at risk.
Wind Chill vs. Air Temperature
While wind chill affects people, not objects, it indirectly impacts pipes by allowing cold air to move through cracks, crawl spaces, and gaps more quickly. Wind drives frigid air into:
Attics
Basements
Crawl spaces
Garages
Exterior walls
This accelerates heat loss from pipes, causing them to freeze much faster.
How Long It Takes Pipes to Freeze
The time varies based on exposure, insulation, and material. On average:
At 20°F: Pipes can freeze in 6 hours or less
At 15°F: Pipes can freeze in 3–4 hours
At 10°F or below: Pipes may freeze in under 2 hours
Copper, galvanized steel, and PEX all freeze at roughly the same temperature, but copper is more prone to bursting because it is rigid.
Why Frozen Pipes Burst
The Pressure Problem Inside the Pipe
Pipes don’t burst at the point where the ice forms. Instead, the blockage increases pressure between the ice and the faucet. As pressure builds, the pipe expands until it finally ruptures—often in a completely different location.
This is why pipes may burst behind walls, under floors, or inside ceilings.
Most At-Risk Areas in a Home
Frozen pipes are most common in places that don’t get consistent heat, including:
Any pipe located near outside air is vulnerable.
Materials That Freeze Faster
Even though all pipes can freeze, the most vulnerable are:
Copper (rigid and expands under pressure)
Galvanized steel (older homes)
PVC (brittle in extreme cold)
PEX handles freezing better but is not immune to ice blockages.
Signs Your Pipes Are Starting to Freeze
No Water or Slow Water Flow
A sudden drop in water pressure—especially during a cold snap—is often the first sign of freezing.
Frost on Pipes
Visible frost or ice buildup on exposed sections of pipe is a major warning.
Strange Odors or Gurgling
A partially frozen pipe can push sewer gases back into the home, creating foul smells or bubbling sounds.
Cold Spots on Walls or Floors
If a section of floor or drywall is unusually cold, a pipe behind it could be freezing.
Sinks That Won’t Drain
Ice can form in drain lines as well, causing slow or blocked drainage.
How to Stop Pipes From Freezing
Keep Your Heat On
Even if you’re away, keep the thermostat set to at least 55°F. Inside temperatures fluctuate more than people think, especially in basements and crawl spaces.
Open Cabinets and Interior Doors
This allows warm air to circulate around pipes under sinks and behind cabinets.
Let Faucets Drip
A slow trickle relieves pressure and keeps water moving, reducing the chance of freezing. Use both hot and cold handles if possible.
Add Pipe Insulation or Heat Tape
Foam insulation sleeves, fiberglass wrap, or electric heat tape can make a huge difference for pipes in cold areas.
Seal Cold Drafts
Use expanding foam, caulk, or weather stripping around:
Foundation cracks
Crawl space vents
Attic openings
Exterior wall gaps
Even small drafts can drop the temperature around a pipe dramatically.
Disconnect Hoses and Shut Off Exterior Spigots
Leaving hoses attached traps water in the line, raising the risk of freezing inside outdoor plumbing.
How to Thaw Frozen Pipes Safely
If you suspect a pipe is already frozen, act fast—but do it safely.
What NOT to Do
Never use:
These methods can cause fires or damage plumbing.
Step-By-Step Thawing Guide
Open the faucet to relieve pressure.
Locate the frozen area (frost, bulging, or a cold section).
Use a hair dryer, heating pad, or portable space heater to warm the pipe gradually.
Start near the faucet and work back toward the blockage.
Continue warming until full water flow returns.
Keep heat circulating in the area for several hours to prevent refreezing.
When to Call a Professional
Call immediately if:
You can’t access the frozen section
The pipe is behind drywall
You hear dripping or spraying
Water flow does not return
You suspect the pipe has already burst
Frozen pipes behind walls can cause severe hidden damage in minutes.
What to Do If a Pipe Bursts
A burst pipe is an emergency. Move quickly to limit damage.
Shut Off Your Water Immediately
Know where your main water shutoff valve is—usually in:
Basements
Crawl spaces
Utility rooms
Exterior walls
Turning off the water instantly stops flooding.
Prevent Further Damage
After shutting off the water:
Move furniture and valuables
Place buckets under active leaks
Use towels to soak up standing water
Turn off electricity in impacted areas
Start drying with fans if safe
Why Water Damage Spreads Fast
Water quickly soaks into:
Carpeting
Drywall
Insulation
Subflooring
Wood trim
Within 24–48 hours, mold can begin to grow. The sooner water is removed and drying begins, the less damage your home will suffer.
How to Prevent Future Freezing Problems
Seasonal Maintenance Tips
Before temperatures drop:
Insulation Upgrades
Adding insulation to attics, basements, and walls improves temperature stability and reduces freezing risk.
Outdoor Spigot and Hose Prep
Use insulated faucet covers and drain exterior lines each fall.
When to Call a Water Damage Expert
Signs of Hidden Damage
Call a professional if you notice:
Mold Risk After a Burst Pipe
Even small leaks can create significant mold growth in days. Professional drying, moisture readings, and structural inspection ensure the damage is fully addressed.
Final Thoughts
Frozen pipes are one of the most preventable causes of winter water damage. Understanding the temperatures that cause freezing, recognizing early warning signs, and taking action during cold snaps can save homeowners thousands of dollars. Whether you’re dealing with a minor freeze, a hidden blockage, or a full pipe burst, quick action is essential.
