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Does PEX Pipe Sweat? What You Need to Know

PEX pipes have gained popularity in recent years due to their flexibility, durability, and affordability. These pipes are made from cross-linked polyethylene materials, making them resistant to corrosion and scaling. However, homeowners may still wonder if PEX pipes can sweat.

So, does PEX pipe sweat? Yes, like any other type of pipe, PEX pipes can sweat. But the amount of sweating depends on several factors, including the temperature and humidity levels in the home.

In this article, we will explore whether or not PEX pipes can sweat and what you can do to prevent it. Let’s get started!

does pex pipe sweat

Does PEX Pipe Sweat?

Yes. But it is less likely to sweat than other types of pipes. Pipe sweating is the process of condensation forming on the outside of a cold pipe, which can cause water damage or mold growth if left untreated.

This is most commonly seen in humid environments, where the temperature of the pipe is significantly colder than the surrounding air. PEX pipe has a smooth surface that is less likely to attract condensation compared to other types of pipes, such as copper or galvanized steel.

Additionally, PEX pipe is often used in areas where sweating is less of an issue. For example, in areas with lower humidity levels or in areas where the pipes are not exposed to the air.

Why Is PEX Pipe Less Likely To Sweat?

PEX pipe is less likely to sweat than traditional copper or steel pipes. This is because they have a higher insulation value than metal pipes. The insulation value of a pipe refers to its ability to resist the flow of heat energy. This value is measured in R-value, which stands for resistance to heat flow. The higher the R-value, the greater the insulating power of the material.  For PEX pipes that are exposed to the outside, a minimum of R3 insulation is required, and R4 or higher may be needed in colder areas.

Furthermore, PEX pipes have a low thermal conductivity when compared to other materials like copper or steel. This makes it less likely for the temperature of the water inside the pipes to reach the dew point of the surrounding air. 

Additionally, PEX pipes do not have a metallic surface like copper or steel, which can also help reduce sweating.

What Causes Sweating in PEX Pipes?

Sweating pipes or condensation occurs due to the difference in temperature between the water inside the pipes and the surrounding air. When warm or hot water flows through the pipe, it increases the temperature of the pipe, causing it to be warmer than the air in the surrounding area.

If the air is cool, this temperature difference causes moisture in the air to condense on the surface of the pipe. Resulting in droplets of water forming on the exterior. It is similar to how water droplets form on the outside of a cold glass of water on a warm day.

Risk Of Pipe PEX Sweating

Although sweating pipes are not necessarily a cause for concern, they can lead to other problems. The moisture that accumulates on the exterior of the PEX pipes leads to several problems, such as

  • Water damage, damage to walls, floors, and other nearby materials
  • Mold and mildew to grow, which can lead to health problems for occupants

Signs/Symptoms Of PEX Pipe Sweating

Here are some signs and symptoms of PEX pipe sweating.

#1. Visible moisture: The most obvious sign of PEX pipe sweating is the presence of visible moisture on the exterior surface of the pipes. This moisture may appear as droplets or beads of water.

#2. Dampness: Even if there are no visible droplets, the exterior surface of the PEX pipes may feel damp to the touch.

#3. Water damage: If the moisture is left unchecked, it can lead to water damage on nearby surfaces, such as walls or ceilings.

#4. Mold and mildew: Moisture can also create ideal conditions for mold and mildew growth, which can harm human health.

#5. Increased humidity: PEX pipe sweating can also increase the humidity levels in a room, which can make it feel uncomfortable and stuffy.

Where To Look For Sweating On Your Piping

Here are some common areas to check for condensation on your piping.

  • Attics or crawl spaces where pipes are exposed to temperature fluctuations
  • Basements or areas with high humidity levels
  • Areas around air conditioning or ventilation systems that can cause temperature changes
  • Areas around hot water heaters or other heat sources can cause temperature changes
  • Exterior pipes that are exposed to outdoor temperature fluctuate
  • Areas around faucets, valves, or other plumbing fixtures that may be leaking or damaged

It’s important to regularly check these areas for any signs of excess moisture or condensation. Then address any issues promptly to prevent potential damage to your plumbing system or property.

How To Prevent PEX Pipes Sweating?

To prevent PEX pipes from sweating, there are several things you can do.

Insulate The Pipes

Adding insulation to the pipes reduces the temperature difference between the water inside the pipes and the surrounding air. This prevents condensation from forming. Insulating PEX pipes is done using foam insulation sleeves that are easily installed over the pipes.

Increase The Air Temperature

Raising the temperature of the air in the room reduces the temperature difference between the water in the pipes and the surrounding air. Increasing the thermostat temperature or use of a space heater helps raise the temperature.

However, it’s important to ensure the temperature is not too high to avoid issues such as high energy bills or overheating.

Reduce Humidity Levels

This helps prevent moisture from condensing on the surface of the pipes. Humidity levels can be reduced by using a dehumidifier or by improving ventilation in the room. Ventilation can be improved by opening windows, using exhaust fans, or installing a ventilation system.

Use a Vapor Barrier

Installing a vapor barrier between the pipes and the surrounding air can help prevent moisture from reaching the surface of the pipes. A vapor barrier is a layer of material designed to prevent moisture movement from one area to another.

It can be installed on the walls, ceiling, or floor and can be made from materials such as plastic or foil.


Let’s consider some frequently asked questions concerning PEX pipe swearing and provide answers to them.

Q: Can Hot Water Pipes Sweat?

Yes, hot water pipes can also sweat. While it is less common than with cold water pipes, it can still occur in certain circumstances.

Q: How do I know if my pipe is leaking and not sweating?

If you see water pooling on the floor or walls, this is a clear sign of a leak. Additionally, if you see brown or yellow stains on walls or ceilings, it’s a leaking sign.

Q: Do Pipe Sweat in Summer and Winter?

Pipes can sweat in both summer and winter. Sweating pipes occur when the water inside the pipe is colder than the humid air surrounding it. In the winter, hot water pipes are more likely to sweat than cold water pipes.

Final Words 

Sweating pipes occur when the surface of a pipe is colder than the dew point temperature of the surrounding air. This causes moisture to condense on the surface. PEX pipes are less likely to sweat than other types of plumbing materials due to their insulating properties.

To prevent sweating PEX pipes, proper installation, insulation, and ventilation are necessary. Although PEX pipes are a durable and cost-effective plumbing option, homeowners should still take preventative measures to address sweating pipes. As with any plumbing issue, it’s always best to seek professional advice if you have any concerns or questions.