You just bought Underground Insulated PEX Pipe and you wanted to make sure you install it properly. After all, you paid a huge amount for that investment.
When it comes to installing underground PEX pipe, proper techniques are crucial for a long-lasting and efficient system.
PEX (cross-linked polyethylene) pipe or PEX underground is a versatile and durable plumbing material suitable for underground installations. It offers excellent resistance to corrosion, freezing, and scaling, making it an ideal choice for various scenarios.
One way of making sure that you get a lot out of this investment is by making sure that you bury it underground DEEP ENOUGH. So the big question is:
HOW DEEP SHOULD YOUR INSULATED PEX PIPE BE BURIED?
Can you use PEX underground? YES! PEX pipes can be buried underground. However, it's important to follow local building codes and guidelines to ensure compliance and the longevity of your plumbing system.
Standard Residential Burial: 2 Feet Deep
Normally, you would bury your underground insulated PEX pipe 2 feet deep (24 inches). This is the right depth for burial for most ground types. Just be diligent enough to backfill it with soil that is not rocky or preferably sand.
For most residential applications, such as running hot water from an outdoor boiler to your home, 24 inches (2 feet) is the recommended burial depth. At this depth, the pipe is:
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Protected from accidental damage during light yard work or gardening
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Below the typical frost line in many moderate climates
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Deep enough to avoid soil movement from surface activity
When backfilling, use clean sand or fine soil free of rocks. Sharp objects can damage the insulation jacket over time, even if they do not puncture the pipe immediately.
To ensure optimal performance and protection against external factors, it is essential to bury insulated PEX pipe at the appropriate depth. The answer to the question if can pex pipe be buried is YES but there are recommendations that we need to consider. The recommended burial depth may vary depending on factors such as climate, soil conditions, and local building codes. We will explore these considerations in detail, enabling you to make informed decisions for your specific project.
Our Insulated PEX 1" – Heat Mizer Brand (for the non-pressurized systems) and Insulated PEX O2 Barrier 1" – Heat Mizer Brand (for pressurized systems) are the best for this application.
Under Driveways or Heavy Traffic Areas: 4 Feet Deep
If your pipe needs to cross under a driveway, parking area, or anywhere that cars and trucks regularly drive, 48 inches (4 feet) is the minimum recommended depth. At this depth, you also need to run the pipe through a conduit, typically a 5-inch or 6-inch PVC sleeve.
The conduit serves two purposes: it protects the pipe from soil compression under vehicle weight, and it allows you to pull and replace the PEX pipe in the future without digging up your driveway.
Pro Tip: If you cannot dig 4 feet deep under your driveway, there is another option. Our heavy-duty Insulated PEX ULTRA 1" pipe can be buried just 2 feet deep even under a driveway, because its reinforced construction is designed to handle the pressure loading from above.
Tips for Burying PEX Pipe Underground
Selecting the Right Type of PEX Pipe
Choosing the correct type of PEX for underground water supply is crucial. We will discuss the different variants available and highlight the features and benefits of each. Understanding these options will help you make an informed decision based on your project requirements. Read more here: What Type of PEX is the Best to Use for Your Outdoor Wood Furnace? PEX A or PEX B?
Proper preparation for Underground PEX Installation
Proper preparation is key to a successful underground PEX pipe installation. Following these guidelines will ensure a smooth installation process. Read this article: Underground Pipe - 5 Ways to NOT Waste Money.
Step-by-Step Installation Overview
What You Need Before You Dig
Before breaking ground, you need to:
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Call 811 (Dig Safe) to have underground utilities marked on your property. This is required by law in the U.S. before any digging project.
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Check local building codes. Some municipalities require permits for underground plumbing work.
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Plan your route. Avoid unnecessary bends and crossings. Straighter runs lose less heat and are easier to install.
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Measure your run. Add 10% to your measured length to account for bends and connections.
Trench Preparation
The trench width should be wide enough to work in comfortably, typically 12 to 18 inches. The bottom of the trench should be:
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Level and free of rocks, roots, or sharp debris
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Covered with 2 to 3 inches of sand or fine soil before laying the pipe
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Slightly sloped if possible to allow drainage away from your building
Laying the Pipe
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Unroll the pipe gradually rather than all at once. PEX has a natural coil memory, and fighting it creates unnecessary tension.
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Avoid kinking. If you need to make a bend, keep the bend radius gradual. A good rule of thumb is that the bend radius should be at least 6 times the pipe diameter.
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Connect sections with push-fit or crimp fittings rated for your pipe type. Do not mix PEX-A and PEX-B fitting systems.
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Seal the pipe ends with caps before burial to prevent soil or moisture from entering.
Backfilling Correctly
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First 6 inches above the pipe: use sand or screened soil. No rocks.
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Above 6 inches: regular backfill is acceptable, but compact it in layers to prevent settling.
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For driveway crossings: compact the fill especially well, and consider using road base gravel above the conduit level.
Burying PEX underground requires careful planning and execution. By following the guidelines in installing underground pex pipe outlined in this comprehensive guide, you can ensure a successful installation that meets the highest standards. Remember to adhere to local building codes and consult professionals when needed. Enjoy the benefits of using PEX for your underground water supply system or other applications.
Ready to install PEX pipe underground? Take the first step toward a reliable plumbing system. Contact our experts today for personalized advice and assistance with your project. Don't miss the opportunity to experience the durability and versatility of PEX pipe for yourself.
Learn more as you watch this video or call our office at 231-861-8200 with any questions you may have!
FAQS
Can you use regular (non-insulated) PEX for underground installations?
Yes, you can bury standard uninsulated PEX underground, but it is only appropriate for cold water supply lines or pressurized systems where temperature retention is not a concern. If you are carrying hot water from a boiler or furnace, you need insulated PEX. Uninsulated hot water lines buried underground will lose most of their heat before reaching the destination, making your system dramatically less efficient.
Does PEX pipe need a protective sleeve underground?
Not always. Under regular yard areas, insulated PEX in good soil does not require a sleeve. However, under driveways, roads, or anywhere subject to heavy loads, a PVC conduit sleeve is strongly recommended and sometimes required by code.
How long does PEX pipe last underground?
PEX is rated for 50 years or more under normal conditions. It resists corrosion, scaling, and biological growth better than copper or steel. The insulation jacket may degrade faster than the pipe itself, especially if the pipe is exposed to UV light above ground, so ensure the above-ground sections are shielded.
Can I bury PEX directly in clay soil?
You can, but clay holds moisture and can shift significantly with freeze-thaw cycles. If your soil is heavy clay, consider laying a thin bed of sand directly under and around the pipe before backfilling with native soil. This reduces stress on the pipe and protects the insulation jacket.
What happens if I bury PEX too shallow?
Shallow burial risks damage from digging tools, lawn care equipment, and frost heaving. More critically for hot water lines, shallowly buried pipes lose heat faster, reducing your system efficiency and increasing your fuel costs.
Can PEX pipe be exposed to sunlight above ground?
No. UV radiation degrades PEX material over time. Any section that transitions from underground to above-ground should be protected with UV-resistant conduit, insulation wrap, or a physical enclosure. This is one of the most commonly overlooked details in outdoor installations.
Do I need a permit to bury PEX pipe?
It depends on your municipality and the type of work. Outdoor boiler connections and domestic water supply lines often require permits. Always check with your local building department before starting work. Unpermitted plumbing can create issues when selling your property or making an insurance claim.
What is the difference between PEX-A and PEX-B for underground use?
PEX-A (made by the Engel method) is more flexible, has better freeze resistance, and can be repaired with a heat gun if kinked. PEX-B (made by the Silane method) is slightly stiffer but still flexible enough for most applications and is often less expensive. For most underground applications, either works well, but PEX-A's greater flexibility is an advantage in cold weather installations where the pipe can stiffen.
Can I Bury PEX Pipe Underground for an Underground Water Supply?PEX pipe is commonly used for underground water supply systems due to its flexibility, durability, and resistance to freezing and corrosion. We will outline the benefits of using PEX for underground water supply and discuss the necessary considerations for a successful installation.
