What Is Supply Line Concealment? (PEX Chases)
Supply line concealment with PEX means routing water tubing inside a planned, accessible chase rather than leaving it exposed. A sound chase protects tubing from fasteners and abrasion, allows correct support and bend geometry, and preserves access to valves and service points. Its size and construction depend on the tubing system, framing, local code, and fire-rating requirements.
Like a film set that hides its workings without blocking the crew, a plumbing chase should conceal the tubing but not defeat future service. I treat “concealed” as a finish choice, not permission to bury a leak, shutoff, or fitting that must remain accessible.
What a PEX supply-line chase is
A PEX chase is a framed or built-in space that routes water-supply tubing through a wall, floor, cabinet, or other part of a building. It separates tubing from damage and finishes while keeping required service points reachable. A chase is not a universal-sized box or a substitute for code-compliant installation.
PEX is cross-linked polyethylene tubing used in water distribution systems. A chase may be formed by a wall cavity, a framed soffit, or a purpose-built enclosure. The route can be hidden behind a removable panel or permanent finish, but valves and other components that require access cannot be sealed behind it.
Use compatible tubing, fittings, and joining methods approved for the system. Follow product instructions and applicable listings, including NSF/ANSI/CAN 61 when potable-water certification is required. ASTM F876 covers PEX tubing, while ASTM F877 covers PEX hot- and cold-water distribution systems. The exact standards and local code requirements depend on the product and jurisdiction.
Key point: Conceal the tubing, not the parts that need inspection, operation, or repair.
Plan the route, code basis, and service points
Route planning means checking the water source, framing, other building systems, and future access before cutting or closing anything. I start with the actual tubing and fitting instructions, then verify the locally adopted plumbing and building codes, permit needs, and inspection steps.
- Trace the supply route. Identify the source, destination, shutoffs, branches, and likely service points. Mark the planned path on the framing or a drawing.
- Check for conflicts. Locate wiring, ducts, vents, drains, structural members, and fire-resistance boundaries. Do not drill or notch a joist, stud, or beam until its limits are confirmed under the applicable code and plans.
- Plan access. Keep required shutoff valves and serviceable components accessible. A removable access panel may be appropriate, but it must provide useful working room, not just a view of the part.
- Confirm local requirements. Code editions and amendments differ. Check the local authority’s adopted code and ask whether a permit or inspection is required before work begins.
Avoid unnecessary concealed joints. A long, continuous run can reduce the number of concealed connections, but the layout must still follow the manufacturer’s rules for fittings and installation. Do not assume that a fitting is permitted to be hidden just because it fits inside the chase.
Before framing, mark the route, access points, and any fire-rated assemblies on the plan.
Set chase dimensions, bend space, and access
Chase sizing means allowing room for the tubing’s outside diameter, any required insulation, fittings, supports, bends, and installation access. No single chase width applies to every project. Use the selected product’s measurements and bend instructions rather than choosing a cavity size by guesswork.
PEX bend limits vary by product and by bend method. There is no one safe minimum radius for all tubing. Check the manufacturer’s minimum bend radius and use listed bend supports where required. If the tube kinks or must be forced into place, revise the route or enlarge the chase.
| Planning item | What to verify | Practical effect on the chase |
|---|---|---|
| Tubing and insulation | Actual outside diameter and insulation thickness, if required | Set clear width and depth from the installed dimensions |
| Bend | Manufacturer’s minimum radius and approved bend support | Allow a gradual turn; do not compress tubing into a tight corner |
| Fitting or valve | Product dimensions and access requirements | Leave room to install, inspect, and operate it |
| Support | Code spacing and manufacturer instructions | Keep space for supports without pinching the tubing |
| Framing protection | Distance from tubing to the framing face | Add required steel protection plates where the threshold applies |
| Fire boundary | Assembly details and an approved firestop method | Preserve the rated assembly at the penetration |
As a planning check, measure the route with the actual tubing and fittings in hand. A drawing that shows only the tube centerline can miss the space needed for a bend, an elbow, or a tool. Leave room to position supports without forcing the tube against sharp edges or other services.
Size the chase from the installed system and service task, not from a generic dimension.
Frame, protect, support, and install PEX
Installation means building the enclosure without weakening structural members, then placing and securing the tubing according to code and product instructions. The chase must protect the line from fasteners and abrasion while allowing it to move as intended by the system design.
Under the 2021 International Plumbing Code (IPC), Table 308.5 gives maximum support spacing for PEX of 32 inches horizontally and 10 feet vertically. Confirm the locally adopted edition and any stricter manufacturer instructions. Support the tubing without crushing it, and use compatible supports where the product requires them.
Where tubing is less than 1¼ inches from the face of a framing member, the applicable code requires protection from fasteners. The 2021 International Residential Code (IRC) specifies a minimum 0.0575-inch, 16-gauge steel protection plate for this situation. Check the adopted code and applicable section for the project. Plates must cover the vulnerable path, not just the hole’s center.
During installation:
- Use tubing, fittings, and joining tools that are compatible and approved for the system.
- Keep tubing clear of sharp edges, hot surfaces, and sources of abrasion.
- Do not force bends or use a bend support that is not listed or allowed for the product.
- Do not bury valves, unions, or other components that the code or manufacturer requires to remain accessible.
- Do not cut, notch, or drill framing beyond permitted limits. If the planned route conflicts with a structural member, redesign it or get qualified direction.
If the chase crosses a fireblocking or fire-resistance assembly, the opening may affect that assembly. Restore it with a listed, assembly-compatible firestop or fireblocking method. Ordinary foam or caulk is not a substitute unless the approved system specifically permits that product and use.
Support and protect the line as it is installed; access and framing safety are part of the design.
Test, inspect, document, and close the chase
Closing the chase means finishing the enclosure only after the tubing has passed the required checks and any required inspection. Testing pressure and method depend on the adopted code and the tubing system. Follow both; do not exceed the product’s rated limits or assume one test method fits every installation.
Before covering the work, check the route for kinks, damage, loose supports, and unprotected framing penetrations. Complete the pressure test according to the local rules and manufacturer’s instructions. If an inspector is required, arrange inspection before covering the tubing.
Take clear photos before the wall or floor is closed. Include the full route, branch locations, supports, plates, penetrations, and access panels. Record measurements from fixed points, such as a corner or floor line. This information can help a future owner avoid drilling into the line.
Finally, close the chase without blocking valves or service points. At penetrations through fire-rated or fireblocked assemblies, use the approved method for that assembly and keep any required access intact.
Do not close the chase until testing, inspection, documentation, and fire protection are complete.
Two common PEX chase scenarios
These examples are planning scenarios, not code approvals or reports of tested installations. They show how the same principles change with the route. For either scenario, final dimensions and methods depend on the actual product, framing, local code, and inspection requirements.
| Scenario | Main design issue | Sound planning response |
|---|---|---|
| Vertical run in a framed wall | Fastener exposure and support | Check vertical support limits, protect tubing near the framing face, and keep shutoffs accessible |
| Horizontal route in a built-out enclosure | Bend space and access | Size the enclosure for the actual bend and fittings, support the run, and provide service access where required |
For a vertical wall route, the key check is whether the tubing sits close enough to a stud face to need a protection plate. Also confirm that supports suit the run and do not pinch the line. A concealed valve should remain reachable if code or product instructions require access.
For a horizontal route, the challenge is often fitting a gradual turn into a shallow enclosure. Measure the bend using the tubing maker’s instructions before framing. If the radius does not fit, increase the chase depth or reroute the line rather than forcing the tube.
Frequently asked questions
These answers summarize the core design checks, but local code and product instructions control the actual installation. Confirm the adopted code edition and ask the local authority having jurisdiction when a requirement is unclear.
What does supply-line concealment mean?
It means routing water-supply tubing inside a planned building space, such as a wall cavity or framed chase, while protecting it and retaining required service access.
Is a PEX chase required by code?
A chase is not a universal code requirement. It is one way to route and protect tubing. The installation still must meet applicable plumbing, building, fire, and product requirements.
How wide should a PEX chase be?
There is no standard width for every project. Size it for the tubing, insulation if required, fittings, supports, bends, and access needed to install and service the system.
How far apart should PEX supports be?
The 2021 IPC lists maximum spacing of 32 inches horizontally and 10 feet vertically. Confirm the locally adopted code and follow stricter manufacturer instructions.
When do I need a steel protection plate?
Under the applicable rule, tubing less than 1¼ inches from the face of framing needs fastener protection. The 2021 IRC specifies minimum 0.0575-inch, 16-gauge steel; verify local requirements.
What bend radius should I use?
Use the minimum bend radius and bend-support instructions for the specific tubing. There is no single radius that applies to every PEX product and bend method.
Can I conceal PEX fittings or shutoff valves?
Do not conceal components that the adopted code or manufacturer requires to remain accessible. Check the rules for the specific fitting or valve before closing the chase.
Can I use ordinary foam around a chase penetration?
Not where a fire-rated or fireblocked assembly needs restoration, unless the approved assembly permits that exact product and use. Select a listed, compatible firestop or fireblocking method.
Should I test the tubing before closing the chase?
Yes. Test and arrange any required inspection before covering the work. Use the pressure and method set by the adopted code and product instructions.
Why photograph a concealed PEX route?
Photos and measurements from fixed points can help identify the tubing path during later repairs or renovation. Document the route before installing the finish.
(This article was written by one of our staff writers, Garrett Vance. Visit our Meet the Team page.)
