Winter has a way of sneaking up on your plumbing.
One minute, everything is flowing like normal, and the next, you turn on the faucet and… nothing. Not even a drip. When that happens, it’s fair to assume the season has officially declared war on your pipes.
In this article, we’re breaking down what causes frozen pipes, what causes frozen pipes to burst, and the biggest causes of frozen pipes in homes of all ages and designs. More importantly, you’ll learn what you can do to keep your plumbing safe when temperatures dip lower than your patience.
So grab that hot cocoa and let’s dive into a little chilly building science.
Key Points:
• Frozen pipes are usually caused by poor insulation, air leaks, and plumbing routed through unconditioned spaces.
• Cold air exposure dramatically increases the risk of frozen and burst pipes.
• Water freezes and expands by 9 percent, creating enough pressure to burst pipes of any material.
• Simple changes like dripping faucets, sealing air leaks, opening cabinets, insulating pipes, and maintaining a consistent temperature can prevent major damage.
• Your home's construction, age, and layout play a major role in whether your pipes stay warm or turn into popsicles.
What Causes Frozen Pipes?
When temperatures plunge below freezing, your plumbing becomes vulnerable – especially in parts of your home that don’t enjoy the same warmth you do.
Poorly Insulated or Uninsulated Areas
Pipes commonly run through:
- Basements
- Crawl spaces
- Exterior walls
- Rim joists
- Attics
- Garages
If these areas have little to no insulation, your pipes are left exposed to cold air. Without thermal protection, the surrounding temperatures drop quickly, leaving water inside the pipes vulnerable to freezing.
Still Water in the Line
Water that isn’t moving freezes much faster.
Exterior faucets and hose bibs are notorious for this, especially if:
- The hose wasn’t disconnected
- The faucet wasn’t drained and shut off properly
Inside the home, allowing a slow drip or small stream keeps water moving – making it far harder for the line to freeze solid.
Air Leaks Letting in Frigid Temperatures
Gaps around certain parts of your home are a big issue.
Gaps around certain areas of the home can invite freezing air directly onto your pipes.
Places to look around include:
- Ventilation
- Wiring holes
- Plumbing penetrations
- Foundations
Cold air plus uninsulated pipes is a recipe for trouble.
How Your Home's Construction Contributes to Frozen Pipes
Even a well-designed home can struggle during extreme cold snaps, but some homes have a layout that makes the battle harder from the start.
Pipes Installed in Unconditioned Areas
If the builder ran plumbing through the listed areas below, then those pipes will freeze significantly faster.
- Crawl spaces
- Exterior walls
- Garages
- Unheated basements
Lack of Pipe Insulation
Pipes without protective sleeves or insulating wraps lose heat quickly.
Something as simple as a pipe “blanket” can add a surprising amount of protection.
Building Design and Thermal Mass
Older homes or those with a higher ratio of exterior wall surface, less thermal mass, or minimal insulation have a harder time retaining warmth.
Because the homes can’t retain the warmth, the risk of frozen plumbing increases.
Poor Construction Practices
Sometimes builders cut corners, leaving behind:
- Unsealed gaps
- No insulation
- Misplaced plumbing runs
- Incomplete air sealing
All of these choices can put your pipes in harm’s way.
What Causes Frozen Pipes to Burst
If you’ve ever left a soda or water bottle in the freezer too long, you already know the result: Boom, instant mess.
Here’s the science behind it.
Water Expands When it Freezes
Water expands by about 9 percent when it turns to ice.
Inside a closed system like plumbing, that expansion creates intense pressure – more than pipe materials are designed to handle, according to the American Red Cross.
It doesn’t matter if your pipes are:
- Copper
- PVC
- PEX
- Galvanized
None of these is designed for the force of expanding ice.
As the ice grows, pressure builds until the pipe wall gives way, bursting from the inside out.
How to Prevent Frozen Pipes
The goal isn’t perfection – it’s prevention.
You can significantly reduce the chances of frozen or burst pipes with a few strategic steps.
1. Insulate Your Pipes
You can insulate your pipes using:
- Foam pipe sleeves
- Pipe wraps
- Heat tape (when appropriate)
This simple upgrade adds a layer of protection, especially in crawl spaces, basements, and exterior walls.
2. Seal Air Leaks
Close gaps in areas like:
- Rim joists
- Foundations
- Plumbing penetrations
- Attic bypasses
Air sealing plus insulation creates a warm “coat” for your entire home, improving energy efficiency and protecting pipes.
3. Maintain Consistent Indoor Temperatures
When you leave home, avoid drastically lowering the thermostat.
A small setback is fine, but a big one can drop interior wall temperatures enough to freeze pipes.
4. Open Cabinets When It's Really Cold
If pipes run through your kitchen or bathroom cabinetry, open the doors to let warm indoor air circulate around the plumbing.
5. Let Faucets Drip During Extreme Cold
A small drip or a small trickle keeps water moving just enough to prevent freezing.
6. Keep Attached Garage Doors Closed
If plumbing runs through the shared wall between your home and garage, keeping the garage door shut helps maintain a buffer of warm air.
Understanding Frozen Pipes and Prevention
Frozen pipes aren’t just an inconvenience; they can lead to serious water damage and costly repairs.
By understanding the causes of frozen pipes and how your home’s construction affects them, you can take smart steps to protect your plumbing when temperatures dip.
If you’re ready to learn more about how air sealing and insulation help safeguard your home, dive into our Learning Center for more building science breakdowns, helpful videos, and homeowner-friendly guides.
Related Articles
How to Keep Pipes from Freezing
Encapsulated Crawl Space vs. Insulation: Do You Need Both?
How to Prepare Your Home for Winter: 10 Must-Do Tips to Get Your House Ready
FAQs: Understanding the Causes of Frozen Pipes
What causes a frozen pipe to burst?
When water freezes, it expands inside the pipe, creating extreme pressure that leads to ruptures, regardless of pipe material.
Can pipes freeze even if my home is newer?
Yes.
Even well-built homes can experience frozen pipes during severe cold snaps, especially if the plumbing is routed through colder areas.
How cold does it need to be for pipes to freeze?
Pipes typically start freezing when the temperatures drop below 32 degrees Fahrenheit, but they’re most vulnerable when the temperature stays below 20 degrees for several hours.
What's the best way to protect pipes in exterior walls?
Air sealing the wall cavity and upgrading insulation – especially with materials that reduce air movement – provides the best long-term protection.
Will dripping faucets really help?
Absolutely.
Moving water freezes far less easily than still water, making a small drip a simple but effective defense during extreme cold.
