Is PEX Good for Cold Weather?

Is PEX good for cold weather?

PEX piping is a good choice for cold climates, but it is not freeze-proof. Water inside PEX freezes just as it does in any other pipe. The difference is that PEX is flexible, so the tubing can often stretch around the ice and return to its original size after thawing instead of splitting. Fittings can still be damaged, and PEX that freezes inside concrete or tightly packed soil can split. PEX needs the same freeze protection as any other water pipe.

This article covers how PEX behaves in freezing weather and how to protect it.

What Is PEX?

PEX is short for cross-linked polyethylene piping.

PEX is a type of plastic piping that is widely used in residential and commercial plumbing applications. PEX is made from high-density polyethylene (HDPE) whose molecules are permanently linked together by a process called crosslinking. Makers use three crosslinking methods, labeled PEX-a, PEX-b and PEX-c.

The resulting product is a pipe that is strong and flexible.

PEX is an excellent alternative to copper or other metal piping, and it can be used for both hot and cold water applications. PEX is easy to install, and it doesn’t require soldering.

Instead, it’s installed with mechanical fittings.

3 Reasons PEX Is Good for Cold Weather

There are three good reasons that PEX is good for colder weather.

Here is each reason in turn.

PEX Is Freeze Resistant

PEX piping resists breaking when it freezes, but it is not freeze-proof.

The secret to its success lies in its flexibility. When water freezes, it expands. This expansion usually puts pressure on pipes, causing them to crack or break.

PEX tubing is elastic, so it can usually expand as the water inside turns to ice and then return to its original size after thawing. This does not always work. The Plastics Pipe Institute notes that PEX that freezes inside a concrete slab or highly compacted soil may not be able to expand evenly and can split.

PEX also conducts heat more slowly than metal pipe, which can delay freezing but does not prevent it. In cold climates, PEX still needs to run through heated spaces or be insulated.

PEX Stays Flexible in the Cold

PEX piping is made of cross-linked polyethylene, which is a type of plastic.

The cross-linking process creates bonds between the molecules in the polymer, making it stronger and more resistant to changes in temperature. PEX keeps its flexibility below freezing. Staying flexible is not the same as being safe from freeze damage, so the water inside still needs protection from freezing.

PEX Lasts Longer

PEX piping is made from cross-linked polyethylene, which is a type of plastic that is highly resistant to both breaking and corrosion.

This makes it an ideal material for plumbing and other applications where long-term durability is a must.

There is no single proven lifespan figure for PEX. Makers typically back the product with a limited warranty. Uponor and SharkBite, for example, each list a 25-year warranty on their PEX pipe.

Durability is not the same as freeze protection. A frozen PEX line still cuts off your water, and the system cannot work as intended until it thaws.

How Cold Can PEX Withstand?

PEX tubing stays flexible well below freezing, but that describes the tubing material only. Water inside PEX still freezes at 32°F.

This flexibility is why PEX is less likely than rigid pipe to split when the water inside freezes. PEX maker Uponor describes PEX as much more freeze resistant than copper and CPVC. PEX is still not immune to cold.

PEX should be installed in heated spaces such as interior walls, floors or ceilings wherever possible. Where it has to run through exterior walls or unheated areas, it should be insulated well enough to prevent freezing.

Thanks to its resistance to breaking when frozen, PEX piping is a popular choice for both residential and commercial applications.

Can PEX Freeze?

Yes, PEX can freeze.

PEX tubing is less likely to split than rigid pipe when it freezes, but the water inside it freezes at the same temperature as in any other pipe.

People often ask about PEX freezing in certain spaces in their homes or office buildings. Here are answers to two of the most common questions.

Will PEX Freeze in the Attic?

Yes, PEX can freeze in an attic. The American Red Cross lists attics among the unheated areas where water supply pipes freeze most often.

The pipe material does not change the freezing point of the water inside it. PEX conducts heat more slowly than metal, which can delay freezing but does not prevent it. Antifreeze solutions are used in outdoor snow and ice melting systems, not in the pipes that carry drinking water.

If PEX in an attic does freeze, the tubing will often survive without bursting. That is not guaranteed, and you will have no water at that fixture until the line thaws.

Insulate PEX in attics, crawl spaces and along outside walls with insulation made for pipes, and seal cracks and gaps that let cold outside air reach them.

Will PEX freeze in a Crawl Space?

Yes, PEX can freeze in a crawl space. Unheated crawl spaces are among the most common places for water pipes to freeze.

Whether it freezes depends on how cold it gets, how long the cold lasts, and how well the pipe is insulated. Insulation slows the process but does not stop it.

Protect PEX in a crawl space the same way as any other water pipe. Insulate it and seal openings that let in outside air.

Every small action you take will only prevent costly and frustrating trouble in the future.

Does PEX Need to be Insulated?

Yes. PEX needs insulation anywhere a metal pipe would need it, including any spot exposed to freezing temperatures.

PEX is flexible and durable, but the water inside it can still freeze, and a freeze can still damage the system.

Insulation slows heat loss and buys time, but it does not add heat. In a long cold spell or a power outage, water in an insulated pipe in an unheated space can still freeze.

There are a few different ways to insulate PEX piping. One common method is to use pre-insulated pipes, which have an insulation layer already attached.

Another option is to wrap the pipe in insulation material, such as foam or fiberglass.

Heat cable is another option for pipes in unheated spaces. On PEX, the Plastics Pipe Institute says the cable should be thermostatically self-regulating and recommended for use on plastic pipe. Follow the instructions from both the cable maker and the pipe maker.

Check that any insulation or sealant that touches the tubing is approved by the PEX maker.

Foam pipe sleeves are a common choice. The American Red Cross suggests products made to insulate water pipes, such as a pipe sleeve.

Good insulation, combined with keeping the surrounding space heated, gives PEX the best chance of getting through a cold snap without freezing.

How Much Does PEX Expand and Contract?

PEX expands and contracts about 1.1 inches for every 100 feet of tubing with every 10°F change in temperature, according to the Plastics Pipe Institute design guide.

At that rate, a 60°F temperature rise lengthens a 100-foot run by about 6.6 inches.

For this reason, PEX should not be pulled tight during installation. Tubing that is pulled tight has no room to shorten when it gets cold, which puts stress on the tubing and its connections.

As a result, it is important to make sure that PEX piping is installed correctly in order to avoid these potential problems.

PEX vs Copper: Which Is Best in Freezing Temperatures?

Both copper and PEX are common types of pipes in plumbing.

Both have their advantages and disadvantages, but how do they compare when it comes to freezing temperatures?

Here is a closer look at the two materials to help you make the best choice for your home.

Copper is a long-established plumbing material. It resists corrosion, but it is rigid, so it is more likely than PEX to split when the water inside freezes. Copper also costs more and takes more skill to install.

PEX, on the other hand, is a newer material that is made from cross-linked polyethylene.

It is flexible and easy to work with, making it a popular choice for do-it-yourselfers. And while PEX can freeze just like any other pipe material, the tubing is less likely to burst when that happens. Fittings and other parts of the system can still be damaged.

So, which is the better choice?

No matter if you live in an area with mild or severe winters, PEX may be the way to go.

PEX is not right for every job. It is not approved for outdoor use where it would sit in sunlight, so exposed outdoor runs need a different material or full protection from UV light.

This video from 1 Tom Plumber freeze-tests PEX and copper pipe:

Is PEX Better Than PVC for Freezing?

PEX is flexible and PVC is rigid, which gives PEX the advantage when water freezes inside the pipe.

PEX is a plastic tubing that is flexible and durable, which helps it survive a freeze.

PVC is rigid and cannot stretch around ice the way PEX can.

Sunlight is a weakness PEX shares. SharkBite says PEX pipe is not approved for outdoor applications or continuous UV exposure and should not be stored in direct sunlight. Uponor rates its AquaPEX pipe for one to six months of UV exposure, depending on the product.

For indoor water supply lines in a cold climate, PEX has real advantages, as long as it is protected from freezing and from sunlight.

How to Thaw Frozen PEX Safely

If a PEX line freezes, warm the frozen section gently. The Plastics Pipe Institute lists pouring warm or hot water over the pipe, wrapping it in a warm moist towel, or blowing hot air on it with a hair dryer or hot air gun. The pipe should not be heated above 180°F.

Never use a torch, propane heater or any other open flame. Do not use an electric resistance pipe thawing device on plastic pipe.

If a pipe or fitting has broken, turn off the water at the main shutoff valve and call a plumber.

Final Thoughts: Is PEX Good for Cold Weather?

PEX is a durable, easy-to-install plumbing option that handles cold better than rigid pipe. It is freeze-resistant, not freeze-proof, so keep it in heated spaces where possible, insulate it everywhere else, and keep it out of the sun.

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Sources

Plastics Pipe Institute (TR-52, PEX freeze-break resistance)
Plastics Pipe Institute (TN-65, insulating plastic pipe)
Plastics Pipe Institute (PEX design and installation guide, chapter 10)
SharkBite (PEX pipe FAQs)
Uponor (FAQ)
American Red Cross (frozen pipes)
IBHS (winter ready)
Consumer Reports (keeping pipes from freezing)
National Center for Biotechnology Information (PEX and drinking water study)

Reviewed October 2026. We corrected the claims that PEX is unlikely to freeze, including in attics and crawl spaces, fixed the expansion figures, removed unsupported lifespan and temperature claims and a personal experience claim, and added thawing and sunlight safety guidance, using the Plastics Pipe Institute, SharkBite, Uponor, the American Red Cross and IBHS.