PEX, or cross-linked polyethylene, has become a very popular option for plumbing in recent years. PEX is flexible, durable, and easy to install, making it a go-to choice for many plumbers and DIYers. When it comes to shower plumbing, using PEX for the water lines is common. However, there is some debate around whether or not PEX should be used all the way to the shower valve itself. In this article, we’ll look at the pros and cons of running PEX to a shower valve and help you decide if it’s the right choice for your project.
Page Contents
What is PEX?
PEX stands for cross-linked polyethylene. It is a flexible plastic tubing that is used for water supply lines in residential and commercial plumbing systems. Here are some key facts about PEX:
- Made from high-density polyethylene plastic that is strengthened by cross-linking.
- Can withstand high temperatures and pressures.
- Doesn’t corrode like metal pipes.
- Resistant to scale buildup.
- Freeze-resistant.
- Quieter than metal or rigid plastic pipes.
- Comes in red, blue, and white for hot, cold, and supply lines.
PEX tubing is flexible and comes supplied on coils, making it very easy to maneuver compared to rigid metal or plastic pipes. It connects using flexible plastic or metal fittings that are crimped, clamped, or expanded to create secure joints.
Overall, PEX provides a versatile and durable piping solution for water supply lines. It has largely replaced copper as the go-to material for plumbers.
Benefits of Using PEX for Shower Plumbing
There are a few potential advantages to running PEX all the way to the shower valve rather than switching to copper or another rigid pipe:
Flexibility
The flexibility of PEX makes the installation process easier compared to rigid pipes. PEX can be bent and snaked through the framing to connect the shower valve without the need for as many fittings, elbows, or soldered joints. This flexibility also allows it to absorb vibrations and shifts which can help prevent leaks.
Fewer Connections
Using PEX for the entire run to the valve results in fewer connections compared to transitioning to copper or galvanized steel. Each joint or connection is a potential failure point, so minimizing connections with PEX can enhance reliability.
Cost Savings
PEX is less expensive than copper and requires fewer fittings. Running PEX rather than copper to the valve can translate into cost savings on materials. The flexibility and ease of installation can also reduce labor time and costs.
Corrosion Resistance
PEX is non-reactive and won’t corrode from exposure to water. This gives it an advantage over metal pipes like copper or galvanized steel which can corrode over time leading to leaks, flow restriction, and water quality issues.
Freeze Resistance
The cross-linked structure of PEX makes it resistant to freeze-thaw damage. It can expand and contract with water as it freezes and thaws. This can help prevent bursting and leakage compared to more rigid pipes.
Potential Downsides of Using PEX for Shower Valves
However, there are also some potential downsides to consider:
Flow Restriction
The inside diameter of PEX tubing is smaller than copper pipes. This means there is greater flow restriction, especially when running long hot water lines. The pressure drop between copper and PEX is likely negligible for most shower applications. But it’s something to keep in mind.
Fitting with Valve
While PEX is flexible, shower valves and mixing valves are made to fit standard copper and threaded pipe sizes. Adapters may be required to properly fit the PEX line into the valve fitting, increasing complexity.
Expansion and Contraction
PEX expands and contracts more than copper with temperature changes. The movement has to be accounted for with joists and studs to prevent noise and rubbing. This usually isn’t a problem with proper installation, but is a consideration.
UV Light Damage
PEX tubing can become damaged and weakened if exposed to UV light from the sun over long periods. Running it inside walls prevents this issue, but it must be shielded from UV in exposed areas.
Permanence
Copper pipes can be un-soldered and reused. But PEX usually cannot be disconnected without cutting. Some plumbers prefer the reusability of copper for this reason.
Expense of Repairs
If a section of PEX does get damaged, the entire length often needs to be replaced. With copper, repairs can be made to small sections only. So PEX repairs may be more labor intensive.
Code Requirements
It’s important to check local plumbing codes before deciding to use PEX up to the shower valve. Some key points:
- Most codes allow PEX for interior water supply lines, but some limit it to under-slab applications only.
- PEX installation must follow code requirements for hangers and supports.
- Some codes require an 18-inch minimum of copper or galvanized steel between the PEX and shower valve.
- A handful of U.S. cities still prohibit PEX, so check municipal codes.
When in doubt, consult with your local permitting office. Following code is crucial to passing inspections and qualifying for permits.
Installation Tips
If you decide to run PEX to the shower valve, here are some tips for proper installation:
- Use the correct PEX size – 1/2 inch minimum is recommended for shower supplies.
- Make sure to use proper hangers and supports spaced correctly.
- Leave room for expansion and contraction between anchors.
- Use bend supports for tight bends to prevent kinking.
- Use a PEX-to-valve adapter if needed for proper fitting.
- Insulate PEX in hot water lines to minimize heat loss.
- Anchor the tubing near the valve for support.
- Label hot and cold lines with tape.
Proper planning of the PEX runs and professional installation following codes is key to creating a reliable shower plumbing system. Consider hiring a professional if you don’t have PEX experience.
Conclusion
PEX can be an excellent material choice for shower plumbing all the way up to the valve. The flexibility, durability, and ease of installation make it preferable in many cases to switching to rigid copper or steel. However, you need to weigh the potential downsides like flow restriction, fitting challenges, and UV exposure based on your specific situation. Consulting local codes is a must before deciding. With good installation, PEX should provide reliable service life with fewer leaks or failures compared to metal piping. Just be sure to plan adequately and take precautions around thermal expansion as needed.
| Pros | Cons |
|---|---|
| Flexibility makes installation easier | Potential for flow restriction |
| Fewer connections and potential leaks | Difficulty adapting to shower valve |
| Resists corrosion and freeze damage | Requires careful UV protection |
| Lower cost than copper typically | Permanent connections |
The key takeaways on using PEX for shower valves are:
- PEX provides flexibility, fewer leaks, and corrosion resistance.
- But PEX has smaller ID, expansion/contraction issues, and UV sensitivity.
- Check local codes – some limit PEX or require minimum copper length.
- Use adapters, hangers, and expansion allowance for proper installation.
- Hire a professional if you don’t have PEX experience.
With the right precautions, PEX can make an excellent material choice all the way to the shower valve. As with any plumbing project, do your research and follow best practices for a reliable finished product. Let us know if you have any other PEX shower plumbing questions!