△
Safety Cue
Task-specific safety guidance for ordinary work hazards.
Project 17
Install a Laundry Box and Washing Machine Valves
Rough-in and test one approved recessed laundry outlet box with hot and cold washing-machine valves and a designed standpipe, trap, and vent connection, using only the DWV design, supply route, and valve orientation supplied by the approved laundry plan.
Field Cue System
These cues appear at the point of work. They identify safety, code, manufacturer, and measurement issues before they become concealed defects, failed inspections, or laundry-room water damage.
✋
Critical Safety Cue
Serious injury, uncontrolled water release, or major property damage is possible.
⛑
Field Safety Cue
Practical work-area safety: framing, lighting, footing, and housekeeping.
▤
Code Alert
Local requirements vary. Verify permit, inspection, and jurisdictional rules.
▧
Manufacturer Cue
Follow product-specific instructions for the box, valves, and fittings.
▱
Measurement Cue
Reference-point, clearance, and verification guidance.
Job Overview
This project qualifies you to rough-in, test, and document one approved recessed laundry outlet box, complete with hot and cold washing-machine valves, a designed trap and standpipe arrangement, and a vent connection built to the approved DWV pattern. The finished work product is one inspected laundry rough-in: a securely mounted box at the correct height and setback, a tested supply branch, a tested DWV branch, and a complete concealment record.
You will review the approved laundry plan; confirm framing and clearances; mark the box location and all piping routes; secure the box and framing support; install the trap, standpipe, and vent using the approved DWV fitting pattern; route and support hot and cold supply piping to listed washing-machine valves; install any required water-hammer arrestors or backflow protection; complete supply and DWV pressure tests; and protect the finished rough-in through wall closure.
This project depends on Chapter 1 work-area isolation and drain-down, Chapter 2 system mapping, the pipe-preparation skills from Chapter 3, the approved joining method taught in Chapters 4 through 6, and the PVC DWV assembly sequence from Chapter 8. It does not repeat those procedures in full; it applies them to one designed laundry outlet.
Skills You Will Demonstrate
- PL-097 — Lay out the laundry box location, elevation, and piping routes from the approved laundry plan.
- PL-098 — Secure the laundry box to framing at the specified height, level, and finished-wall setback.
- PL-099 — Connect hot and cold water supplies to the box using the approved material and joining method.
- PL-100 — Connect the standpipe to the approved trap, trap arm, and vent arrangement.
- PL-101 — Install hot and cold washing-machine shutoff valves in the specified orientation.
- PL-102 — Test the completed supply and DWV connections and document the laundry rough-in before concealment.
Where This Skill Fits
This project brings together the water-supply joining skills from Chapters 4 through 6, the fixture-stop and valve skills from Chapter 7, and the PVC DWV assembly sequence from Chapter 8, applied to a single dedicated appliance outlet. The same isolation, drain-down, and documentation discipline established in Chapter 1 controls how this rough-in begins and how it is protected until finish work.
The trap, standpipe, and vent design used here follows the same DWV fitting-pattern, slope, and venting principles taught in Chapters 8 and 9, and the completed pressure and DWV tests use the same test-and-document standard applied throughout the book. This project does not teach a new DWV design method; it applies the approved design supplied by the laundry plan.
Scope and Intended Use
This project covers:
- reviewing and laying out the approved laundry plan, box model, valve type, supply sizes, standpipe and trap design, vent route, drain size, and height requirements
- securing the laundry box to framing at the specified location and setback
- installing the approved trap, standpipe, and vent connection using the approved DWV fitting pattern and slope
- routing and supporting hot and cold supply piping to the box
- installing listed washing-machine valves in the specified orientation, plus any required water-hammer arrestors, backflow protection, or auxiliary pan connection
- completing the required supply pressure test and DWV test before concealment
This project does not authorize the learner to:
- invent a standpipe height, trap size, trap-arm length, vent arrangement, or branch size that is not supplied by the approved laundry plan or adopted code
- weaken or unsafely cut structural framing members to install the box or route piping
- conceal any supply or DWV connection before the required pressure test, DWV test, and inspection have passed
- proceed with a drain-flow test before the approved DWV system is complete and inspected
Any condition that conflicts with the approved laundry plan, adopted code, or manufacturer instructions must be resolved before work continues rather than substituted with an assumed design.
Reference Conventions
Establish these references from the approved laundry plan before any framing opening or piping route is marked.
| Term | Definition |
|---|---|
| Box centerline | The horizontal reference line locating the laundry box on the wall framing, as supplied by the approved plan |
| Finished-wall setback | The distance from the framing face to the box flange that positions the box flush with the specified finished-wall thickness |
| Standpipe height | The vertical distance from the trap weir to the top of the standpipe, as specified by the approved plan; not to be estimated or substituted |
| Trap-arm length and slope | The horizontal run and fall from the trap to the vent connection, as specified by the approved DWV design |
| Hot-left, cold-right orientation | The standard washing-machine valve orientation unless the approved project specifies a different orientation |
| Test boundary | The capped or plugged extent of the supply and DWV piping subjected to the required pressure and DWV tests |
Laundry Rough-In Design Record
Before marking any framing opening, record the approved design values directly from the laundry plan onto the Laundry Rough-In Worksheet:
Box model: ______ Box centerline height: ______ Finished-wall setback: ______
Standpipe height: ______ Trap size: ______ Trap-arm length and slope: ______ Vent size and route: ______
Supply material and size: ______ Valve model: ______ Water-hammer arrestor or backflow device required: ______ (Yes/No)
Prerequisites
- Completed Work-Area Readiness Worksheet from Chapter 1 for the wall section receiving the laundry box
- The approved laundry plan, box model documentation, valve schedule, and DWV design showing standpipe height, trap size, trap-arm length, vent route, and branch size
- Confirmed licensed, permitted, or inspection status required for the DWV and supply work in this project
- Open framing at the laundry location with confirmed stud position and no undisclosed structural, electrical, or other utility conflict
- Familiarity with the approved supply joining method from Chapters 4 through 6 and the PVC DWV assembly sequence from Chapter 8
Common Field Fundamentals
A laundry rough-in fails most often when the box, trap, and supply piping are installed to convenient field dimensions instead of the approved plan. Every dimension in this project — box height, setback, standpipe height, trap-arm length, vent size — must come from the laundry plan or adopted code, never from an estimate made at the wall.
LayoutBox centerline, elevation, and all piping routes marked from the approved plan before cutting
Framing supportBox secured to structural backing without weakening framing members
DWV rough-inTrap, standpipe, and vent built to the approved fitting pattern and slope
Supply rough-inHot and cold piping routed, supported, and protected to the box
Valve installationListed washing-machine valves set in the specified orientation
Auxiliary protectionWater-hammer arrestors, backflow devices, or pan connections installed where required
TestingSupply pressure test and DWV test both completed and passed before concealment
DocumentationConcealed piping, dimensions, and inspection approval recorded on the worksheet
Design Fidelity and Test Sequencing
The DWV design supplied by the laundry plan controls the standpipe height, trap size, trap-arm length, and vent arrangement. Do not adjust these values to make the rough-in easier to build. Complete the supply pressure test and the DWV test independently, and do not run a drain-flow test through the standpipe until the vent and trap arrangement have passed inspection.
PL-097 – PL-102
Laundry Rough-In / Supply and DWV Installation / Test and Documentation Qualification
Install a Laundry Box and Washing Machine Valves
A. Finished-Project Specification
Quantity: one recessed laundry outlet box, secured to framing at the approved centerline, elevation, and finished-wall setback, connected to one approved trap, standpipe, and vent arrangement, supplied by hot and cold piping to listed washing-machine valves, tested under supply pressure and DWV test, and documented on one completed Laundry Rough-In Worksheet.
B. Laundry Rough-In Schedule
| Item | Target Condition | Verification Method |
|---|---|---|
| Box location | Centerline, elevation, and finished-wall setback match the approved laundry plan | Level and tape-measure check against the plan |
| Framing support | Box secured square, level, and to structural backing without weakened framing | Visual inspection and level check |
| Trap and standpipe | Approved trap and standpipe height installed per the DWV design | Measurement against the approved plan |
| Trap arm and vent | Approved DWV fitting pattern, slope, and vent connection completed | Slope check and visual inspection |
| Supply piping | Hot and cold piping routed, supported, and protected to the box | Visual inspection of supports and protection plates |
| Valve installation | Listed washing-machine valves installed in the specified orientation | Visual inspection against the valve schedule |
| Testing | Supply pressure test and DWV test both completed and passed | Test-gauge or water-test observation over the required duration |
C. Material Takeoff
- Laundry box and valves: one approved recessed laundry outlet box and one set of listed washing-machine valves matching the valve schedule.
- DWV materials: approved trap, standpipe, trap-arm, and vent fittings and pipe matching the specified sizes and the Chapter 8 solvent-cement joining materials.
- Supply materials: hot and cold supply pipe and fittings matching the approved joining method from Chapters 4 through 6.
- Supports and protection: pipe supports at the specified intervals and protection plates at every framing penetration within the prohibited fastener zone.
- Auxiliary devices: water-hammer arrestors, backflow protection, drain funnel, or auxiliary pan connection where required by the approved plan.
- Documentation: one Laundry Rough-In Worksheet, plus photographs of the box, trap, standpipe, vent, supply connections, and test results.
D. Acceptance Standards
| Check | Standard |
|---|---|
| Box position | Centerline, elevation, and setback match the approved plan within the plan's stated tolerance |
| Framing security | Box square, level, and fastened to structural backing without weakened framing members |
| DWV design fidelity | Standpipe height, trap size, trap-arm length, and vent arrangement match the approved plan exactly |
| Supply installation | Piping routed without kinks, twists, or unsupported spans, and protected at all penetrations |
| Valve orientation | Hot and cold valves installed in the specified orientation and operate through their full range |
| Test results | Supply pressure test and DWV test both pass at the required pressure or method and duration |
| Documentation | Laundry Rough-In Worksheet complete with design values, test results, and inspection approval |
E. Plan Review and Layout Definition
- Review the approved laundry plan, appliance dimensions, box model, valve type, supply sizes, standpipe and trap design, vent route, drain size, height requirements, and inspection sequence. Record every design value on the Laundry Rough-In Worksheet before marking anything.
- Confirm that framing is open and the wall location provides appliance, hose, electrical, dryer, and service clearances. Verify against the approved plan's stated clearance values.
- Verify that the DWV design has been approved; do not invent standpipe height, trap size, trap-arm length, vent arrangement, or branch size. Stop and obtain the missing design value if any of these is not supplied by the plan or adopted code.
- Mark box centerline, elevation, stud position, drain route, vent route, and supply entries. Confirm stud position with a stud finder before marking any penetration.
F. Framing Support and Box Installation
- Install required framing support without weakening structural members. Confirm the support method against the framing design before fastening.
- Secure the laundry box square, level, and at the specified finished-wall setback. Verify with a level and tape measure against the recorded design values.
G. DWV Rough-In: Trap, Standpipe, and Vent
- Install the approved trap and standpipe arrangement below the box. Confirm the standpipe height matches the recorded design value before proceeding.
- Connect the trap arm and vent using the approved DWV fitting pattern and slope. Follow the Chapter 8 assembly sequence for measuring, dry-fitting, priming, and solvent-cementing each joint.
- Support DWV piping and protect framing penetrations. Install supports at the specified intervals and protection plates at every penetration within the prohibited fastener zone.
H. Water-Supply Rough-In and Valve Installation
- Route hot and cold supply piping to the box using the approved material and joining method. Follow the applicable Chapter 4, 5, or 6 joining procedure exactly.
- Install protection plates and pipe supports. Confirm spacing meets the manufacturer- and code-controlled interval.
- Connect the listed washing-machine valves in the specified hot-left and cold-right orientation or approved project orientation. Verify orientation against the valve schedule before final tightening.
- Install any required water-hammer arrestors, backflow protection, drain funnel, or auxiliary pan connection. Install each device exactly as specified by the manufacturer instructions or approved plan.
I. Testing and Inspection
- Cap or plug supplies and DWV openings for testing. Confirm every cap and plug is secure before pressurizing or filling the system.
- Complete the required supply pressure test. Apply only the permitted test pressure and duration under the required supervision.
- Complete the required DWV test and inspection. Use the approved DWV test method and observe every joint for leakage.
J. Flush, Connect, and Operational Testing
- Flush the supply lines before connecting appliance hoses. Direct flushed water into approved containment.
- Install listed washing-machine hoses or leave documented capped connections for appliance installation. Record which condition applies on the worksheet.
- Operate both valves and inspect for leakage. Cycle each valve through its full range and observe the valve body, stem, and connections.
- Conduct a controlled drain-flow test only after the approved DWV system is complete. Confirm the vent and trap arrangement have passed inspection before running water through the standpipe.
K. Protection and Documentation
- Protect the box and connections during wall finishing. Cover exposed piping and the box opening before insulation, drywall, or finish work begins.
- Document concealed piping, tests, and inspection approval. Complete every field on the Laundry Rough-In Worksheet before concealment.
Common Readiness Inspection
Inspect every completed laundry rough-in using the same checks regardless of box model or specific DWV design.
- Layout check: confirm box centerline, elevation, and setback match the approved plan.
- Framing check: confirm the box is square, level, and secured to structural backing without weakened framing.
- DWV check: confirm standpipe height, trap size, trap-arm length, and vent arrangement match the approved design exactly.
- Supply check: confirm piping is routed, supported, and protected without kinks or twists.
- Valve check: confirm both valves are installed in the specified orientation and operate through their full range without leakage.
- Test check: confirm both the supply pressure test and DWV test have passed before concealment.
Complete the Laundry Rough-In Worksheet in the Inspection Checklist section below before beginning Project 18.
Image Placeholder
Image Placeholder
Image Placeholder
Image Placeholder
Image Placeholder
Failure Points and Troubleshooting
Cleanup
This project ends with a tested, documented, and protected laundry rough-in ready for wall finishing or, where the schedule allows, appliance hookup.
- Remove test caps only after both tests have passed and inspection approval is recorded
- Clean solvent-cement residue and supply-joint debris from the box and surrounding framing
- Confirm protection remains over the box opening and exposed piping before finish work begins
- Label the hot and cold valves and the vent location for future reference
- Store the Laundry Rough-In Worksheet with the project's concealed-work records
Field Terms
- Box Centerline
- The horizontal reference line locating the laundry box on the wall framing, as supplied by the approved plan.
- Finished-Wall Setback
- The distance from the framing face to the box flange that positions the box flush with the specified finished-wall thickness.
- Standpipe Height
- The vertical distance from the trap weir to the top of the standpipe, as specified by the approved plan.
- Trap-Arm Length and Slope
- The horizontal run and fall from the trap to the vent connection, as specified by the approved DWV design.
- Hot-Left, Cold-Right Orientation
- The standard washing-machine valve orientation unless the approved project specifies a different orientation.
- Water-Hammer Arrestor
- A device that absorbs the pressure spike created when a washing-machine solenoid valve closes rapidly.
- Test Boundary
- The capped or plugged extent of the supply and DWV piping subjected to the required pressure and DWV tests.
- Laundry Rough-In Worksheet
- The document recording box location, DWV design values, supply and valve installation, test results, and inspection approval.
Skill Check
- Why must the standpipe height, trap size, trap-arm length, and vent arrangement come only from the approved laundry plan or adopted code?
- What must be confirmed about framing and clearances before the laundry box is marked and cut in?
- Why is the box centerline, elevation, and setback recorded before any DWV or supply piping is installed?
- What determines whether washing-machine valves are installed hot-left, cold-right, or in a different orientation?
- When must water-hammer arrestors, backflow protection, or an auxiliary pan connection be installed?
- Why must the supply pressure test and the DWV test be completed as two separate tests?
- Why must a drain-flow test wait until the approved DWV system is complete and inspected?
- What must the learner do if the DWV design supplied by the plan is missing a required dimension?
- What information must be recorded on the Laundry Rough-In Worksheet before concealment?
- Why must protection remain over the box and piping during wall finishing?
Competency Rubric
| Competency | Independent Pass Standard | Not Demonstrated | With Assistance | Independently |
|---|---|---|---|---|
| PL-097 | Lays out the laundry box location, elevation, and piping routes matching the approved laundry plan exactly | |||
| PL-098 | Secures the laundry box to framing square, level, and at the specified finished-wall setback | |||
| PL-099 | Connects hot and cold water supplies to the box using the approved material and joining method without leakage | |||
| PL-100 | Connects the standpipe to the approved trap, trap arm, and vent arrangement matching the DWV design exactly | |||
| PL-101 | Installs hot and cold washing-machine shutoff valves in the specified orientation and confirms full operating range | |||
| PL-102 | Tests the completed supply and DWV connections, passes both tests, and documents the laundry rough-in before concealment |
Mark one column per competency. Only Demonstrated Independently awards the competency; Demonstrated with Assistance authorizes additional supervised practice but does not complete the requirement.
Inspection Checklist — Laundry Rough-In Worksheet
| Item | Target Condition | Result | Pass/Fail | Correction (if any) |
|---|---|---|---|---|
| Box location | Centerline, elevation, and setback match the approved plan | |||
| Framing support | Box square, level, and secured to structural backing | |||
| Standpipe and trap | Height, size, and configuration match the approved DWV design | |||
| Trap arm and vent | Approved fitting pattern, slope, and vent connection completed | |||
| Supply piping | Routed, supported, and protected without kinks or twists | |||
| Valve installation | Specified orientation, full operating range, no leakage | |||
| Supply pressure test | Passes at the required test pressure and duration | |||
| DWV test | Passes using the approved DWV test method |
Unresolved deficiencies and correction plan: ____________________________________________
Rough-in declared ready for concealment: ______ (Pass/Fail) Date: ____________ Builder name: ____________
Performance Check
With the box secured, the DWV rough-in complete, the supply piping and valves installed, and both required tests passed, review the finished rough-in against the Acceptance Standards table and confirm the box location matches the approved plan, the standpipe height, trap size, trap-arm length, and vent arrangement match the approved DWV design exactly, supply piping is supported and protected without kinks or twists, both washing-machine valves operate through their full range without leakage in the specified orientation, and both the supply pressure test and the DWV test have passed. Complete the Laundry Rough-In Worksheet and correct any failed item before beginning Project 18. If an item fails, identify whether the error occurred in layout, framing support, DWV assembly, supply installation, valve installation, or testing before correcting it and re-running the affected check.
Project Closeout
You have completed the seventeenth project in the residential plumbing sequence: installing a laundry box and washing machine valves. This project required you to lay out the laundry box, secure the box to framing, connect hot and cold supplies, connect the standpipe, install shutoff valves, and test laundry connections (PL-097 through PL-102).
You now have a tested, documented laundry rough-in that carries directly into the appliance and water-heater work that follows: the same design-fidelity discipline — using only the dimensions and configurations supplied by the approved plan, manufacturer instructions, or adopted code — controls the water-heater connector replacement in the next project.
Protect the completed rough-in, keep the Laundry Rough-In Worksheet with your concealed-work records, and do not connect the appliance hoses until wall finishing is complete and the fixture stops have been installed.