At What Temperature Do Pipes Freeze and How Do You Protect Them?

When a cold front strikes, many homeowners wonder if their pipes will freeze. While water freezes at 32 degrees Fahrenheit or lower, what temperature pipes freeze at depends on multiple factors. In addition to outdoor temperatures, whether pipes will freeze depends on location, how insulated they are, where you live, and how long the temperature stays at or below freezing. Here’s everything you need to know about frozen pipes, how to prevent them, and what to do if it happens.

What Temperature Will Cause My Pipes to Freeze?

Pipes run the risk of freezing at temperatures below 32 degrees Fahrenheit, especially if they're not insulated, but most insulated pipes start to freeze at 20 degrees Fahrenheit or below. When temperatures drop below 20 degrees, it usually takes six hours for insulated pipes to freeze, while temperatures between 20 and 32 degrees are likely to freeze pipes after about 12 hours. Knowing how long a freeze can take to set in can help you keep your pipes from freezing.

Remember that these are outdoor temperatures rather than your pipes’ temperatures. In other words, an outdoor temperature of 20 degrees isn’t necessarily going to cause the pipes on your property to freeze.

What Temperature Do Pipes Bursts?

When water freezes, it expands, which can create pressure in your pipes and cause them to burst. So your pipes can potentially burst when temperatures drop below 32 degrees Fahrenheit. However, the time it will take for them to burst depends on just how cold it is and for how long. A quick cold snap isn't likely to make them burst, but if temperatures are very low for more than four to six hours, your pipes can burst.

Factors That Impact Whether Your Pipes Will Freeze

As confusing as it may be to figure out which temperature will cause your pipes to freeze, there are several ways you can determine whether your home is at risk of freezing pipes come winter.

Where You Live

Most home designs in the North protect against freezing. They can tolerate colder temperatures because the pipes are inside the home in warm, insulated locations to prevent frozen pipes. On the contrary, if you live in the South or in a warmer climate where below-freezing temperatures occur very rarely, your home is at risk of frozen pipes at a much higher temperature—and your pipes are more likely to freeze in 20 degrees.

Pipe Location

Exterior pipes are most susceptible to freezing temperatures because of exposure to the elements. These pipes will be the first to freeze, but pipes themselves do offer some protection from cold temperatures. This means exposed pipes will freeze after just a few hours in temperatures of around 20 degrees but may not freeze at 32 degrees for half a day. 

Pipes closest to an exterior-facing wall, an attic, or windows are more protected than exterior pipes. However, they are still likely to freeze after three or four hours in temperatures below 20 degrees. Meanwhile, pipes inside your home may take up to six hours to freeze at 20 degrees.

Level of Insulation

Beyond the natural insulation of your home, you can also protect your pipes to some extent with insulation. According to Energy Saver, the best pipe insulation to prevent freezing can raise your water temperature by 3 to 4 degrees. A few ways you can insulate your pipes include:

• Heat tape

• Spiral-wrap insulation

• Fiberglass insulation

• Spray foam insulation

• Self-sealing foam insulation

Type of Pipes

Some pipes simply freeze faster than others. Copper pipes freeze faster than PEX piping, which has more freeze resistance than other piping. This is because copper is a good conductor of heat, so heat loss occurs faster. 

Overall Temperature 

If the temperature only drops below freezing for a few hours, your pipes might not have enough time to freeze. On the other hand, sustained temperatures below 20 degrees—especially for six or more hours—will likely result in frozen pipes without preventative measures.

How to Prevent Frozen Pipes From Bursting

Prevention is the best way to protect your pipes from bursting and costing you hundreds, if not thousands, in repairs. Here are some tips for preventing a plumbing emergency as part of your home winterization routine:

• Install insulation for exterior pipes and pipes close to walls, windows, and attics.

• Insulate/winterize outdoor faucets.

• Keep your heat above 55 degrees.

• Leave your cabinets and doors open for airflow.

• Drip your faucets.

• Disconnect hoses from your outdoor pipes.

Signs of Frozen Pipes

The weather forecast is in, and you see upcoming prolonged periods of below-freezing temperatures. Even with the most ambitious measures, your pipes can still freeze, so knowing how to find frozen pipes can help you prepare for worst-case scenarios. 

Keep an ear out for whistling or clanking sounds inside pipes, and pay attention to any suspicious smells. Inspect accessible pipes to look for bulging, cracking, ice, drips, and water spots on the ceiling or walls.

What to Do When Pipes Freeze

When water freezes, it expands, leading to burst pipes. At the first sign of frozen pipes, you’ll want to take action to thaw your pipes. Here’s what to do if your pipes freeze:

1. Keep your faucets on (even if the water stops coming out).

2. Use a hair dryer, space heater, electric heating pad, or hot towels to thaw the pipes.

3. Continue to apply heat until water comes out of your pipes again.

4. Check all other faucets to find frozen pipes and repeat these steps if necessary.

Just a note: You should never attempt to thaw a frozen pipe using an open flame, as this can be extremely dangerous. It’s also not a good idea to pour boiling water down a drain pipe or on the outside of pipes, as this water can freeze and make the issue worse.

Cost to Repair Burst Pipes

The cost to repair a burst pipe is $500, on average, if you choose to hire a plumbing repair pro. While you might think you can DIY this repair to save money, we highly recommend hiring a plumber to understand the root cause of the issue causing the pipe to burst and ensure that the job is done correctly the first time. Plumbing repair mistakes can lead to water damage and further problems—all of which will likely cost more than if you hired a professional to fix the issue from the get-go.