Wall-Hung Toilet With In-Wall Tank: Complete Installation

This blog explains how to plan and install a wall-hung toilet with a concealed in-wall tank and carrier inside 2×6 framing. It covers layout, framing adjustments, carrier height and alignment, drain and water connections, electrical for a smart bidet seat, blocking and bracing, and the finish-ready setup. It also records key construction choices from a related garage build (overhangs, sheathing, storm performance) where lessons inform the bathroom work, so any builder can apply them in similar conditions.

Context and Lessons From the Shell: Overhangs, Sheathing, and Structural Tie-In

Before the bathroom work, the project established several exterior details that influence interior utilities and finishing:

• Overhangs (hoods):

  • Framing: 2×6 members with a beefed-up 2×8 beam at one side.

  • Depths: 16 in on the sides, 20 in at front and back.

  • Fastening: 5-in GRK structural screws into framing and trusses.

  • Sheathing: ZIP System pieces were added and taped; two major storms verified a tight, dry assembly.

  • Future brackets: Five decorative brackets front and five rear, designed to be structural for added stiffness.

• Why overhangs were site-built (vs prebuilt ladders):

  • The chosen method allowed continuous sheathing integration that ties truss to wall and first floor to ground floor through the ZIP panel layout.

  • Tradeoff: Working height forced multiple scaffold resets. For larger runs (e.g., the main house), a different approach may be faster, such as extending rafter truss tails and sheathing around them.

• Takeaway: The envelope was tightened early and connections between structural planes were improved, which matters when cutting in new mechanical rough-ins (plumbing/electrical) so penetrations remain controlled and well-marked.

Why Choose a Wall-Hung Toilet With a Concealed Tank

• Space optimization: The tank sits in the wall, freeing floor area and simplifying cleaning.

• Adjustable bowl height: Frame legs are adjustable; bowl rim can be set higher than standard for comfort (e.g., 18 in above finished floor).

• Serviceability: The flush/ fill components are accessed through the flush panel opening. The system uses no wax ring; instead it employs a high-quality rear discharge connection.

• Smart seat readiness: Concealed tank designs pair well with bidet seats, which need power, a dedicated 120 V circuit (typical 15 A), and a nearby water connection.

System Overview

• Carrier: Powder-coated steel frame with adjustable feet, rated for bowl and user loads (follow the carrier’s load spec).

• Drain: 3-in PVC to the main line, connected via supplied discharge fitting and a 4-band hubless (no-hub) coupling with internal stop.

• Water: 1/2-in PEX (in this case, PEX-a / Uponor) on a male NPT adapter to the carrier’s fill valve.

• Electric: Dedicated 15 A GFCI-protected receptacle for the bidet seat heater/pump, placed low and hidden behind the skirt line with an angled plug routing.

• Framing depth: Works in 2×4 or 2×6 walls; 2×6 adds insulation buffer behind the tank (useful in cold climates).

• Finish: A flush-panel opening (with “mud ring”) gives full access to flush/fill valves and solenoids for maintenance.

Planning & Layout

1. Confirm framing bay

   • If studs were originally placed at 16 in o.c. without accounting for the carrier width, reposition as needed.

   • When the wall was first framed without a selected carrier, two studs ended up too close. To solve that, studs were slid after freeing top/bottom fasteners (e.g., snipping nails at plates and re-fixing correctly).

2. Protect the concealed tank

   • Use bright marking (paint/markers) on the exterior sheathing and the interior face to warn against future fasteners in the tank zone.

   • Plan tile backer and siding work so no screws penetrate the tank corridor.

3. Blocking and backing

   • Provide 2×6 blocking on both sides of the carrier, at and above bowl bolt height, per the manufacturer’s spec.

   • Add extra horizontal blocking as needed for tile backer seams and accessories.

4. Window and finishes

   • A casement window is planned above the toilet. Size and sill height dictate additional double 2×6 blocking beneath the window stool.

   • Full-height tile or half-height tile are both compatible; leave a clean, continuous plane.

Height Setting: Bowl Rim and Carrier

• Target bowl rim height: 18 in above finished floor (AFF) for comfort (vs. typical 16.5 in).

• Manufacturer’s frame height: The spec calls for a carrier top at 48-5/16 in AFF for a standard 18-in rim.

• Adjust for actual floor buildup: If tile + underlayment equals 3/4 in, add that to the framing mark and set the carrier top to ~49 in AFF so the bowl rim lands at 18 in finished.

Procedure

• With the carrier on a temporary 2×4 (simulating sill plate), extend/lock the adjustable feet until a tape at the carrier’s reference point reads 49 in to the current subfloor.

• Tighten the carrier’s leg screws to lock height.

Drain Connection: Accurate, Square, and Serviceable

Components

• Supplied carrier discharge elbow.

• 4-band no-hub coupling with internal stop.

Key measurements

• The no-hub band depth and internal stop matter: the internal stop sits roughly 1.5 in from the band edge. Plan the PVC cut so the band lands on the intended slope of the carrier outlet and stops at the internal rib.

Steps

1. Dry-fit the discharge

   • Mount the carrier’s discharge elbow using the correct mounting holes.

   • For straight-down exit, use the front hole in the bracket (rear hole is for angled exits that pass through the frame).

2. Square cut the 3-in PVC

   • Mark the main line from the sill plate down ~3.5 in to account for the hubless stop and the desired coupling position.

   • Use a “wrapper” trick: wrap sandpaper or tape around the pipe to scribe a straight, square line and cut. Deburr the edge with emery cloth.

3. Set the coupling

   • Slip the no-hub over the PVC, align so the internal stop and band land exactly at the planned slope on the discharge.

   • Orient screw heads outward for future torqueing access.

4. Correct misalignments

   • If the discharge is leaning or the coupling is forced off-square, adjust the wall framing and/or pipe path.

   • One practical fix: notch the sill and a touch of subfloor behind it to let the 3-in line move forward a few degrees.

   • Hold the pipe forward in the new notch with a wood wedge so the coupling sits square. The result should bring the carrier face flush with stud faces.

5. Tighten bands

   • Tighten bands uniformly. Many manufacturers specify torque (e.g., 60 in-lb); use a torque wrench if available. If not, tighten evenly and recheck after rough-in inspection.

Water Supply: PEX-a Connection to Fill Valve and Smart Seat Tee

Components

• 1/2-in male NPT → PEX-a adapter (Uponor type) to the carrier’s internal fill valve port.

• PEX-a tubing routed within the stud bay, protected from fasteners.

• Built-in shutoff at the carrier and a second shutoff for the bidet seat feed.

Steps

1. Install the adapter at the tank

   • Use PTFE tape (and a rated pipe joint compound if desired) on the male threads.

   • Tighten with a 7/8 in socket (clearance in the cavity can limit wrench types).

2. Route PEX

   • Keep the PEX line inside the bay, away from screw paths.

   • Pre-drill the adjacent 2×6 blocking with a large hole (≈2-1/4 in) so the PEX can pass before the block is fastened, because access is tight after the block is in place.

3. Valves

   • Use the carrier’s built-in shutoff for tank service.

   • Provide a separate shutoff for the seat’s branch, typically near the seat connection.

4. Insulate the copper/PEX

   • Where copper pigtails are present, install pipe insulation during wall insulation to avoid condensation and protect against cold spots.

Electrical: Dedicated 15 A Circuit for Bidet Seat

• Load: Smart bidet seats draw significant power for heaters and pumps; a shared circuit risks nuisance trips (e.g., hair dryer + seat).

• Plan: Install a dedicated 15 A GFCI-protected receptacle close to the toilet.

• Placement:

  • A concealed metal box can be mounted to the carrier frame low in the bay.

  • The seat’s angled plug and cord route down through a grommet hole and loop back to the outlet so it remains hidden.

  • Bond the carrier frame by using a metal box with proper equipment grounding.

Setting and Anchoring the Carrier

1. Align the face

   • The carrier front plane should be flush with the stud faces to simplify tile backer and finish layers.

2. Fasten to structure

   • Lag or structural screw the carrier to side 2×6 blocks at the manufacturer’s holes.

   • Anchor the feet to the slab or subfloor (per spec) through the sill plate with the prescribed anchors or screws.

3. Final checks

   • Verify bowl bolts are plumb and level, spaced to the bowl specification.

   • Confirm discharge outlet and water inlet stubouts are aligned and protected with temporary caps.

Adjusting Framing for Perfect Fit

• Stud relocation: If studs conflict with the carrier, free the nails/screws at top and bottom plates, then slide and re-fix them in the proper position.

• Sill and floor notching: Small notches may be required for the 3-in drain to sit correctly. Add nail plates where plumbing passes through wood.

• Add blocking now: Install additional 2×6 studs or flat blocking on both sides of the carrier to create solid anchorage for tile backer, accessories, and a window stool.

Hanging the Bowl (Test-Fit) and Seat Power Routing

• Temporary bowl hang:

  • Before closing walls, hang the bowl briefly to verify bolt projection, elevation, and discharge alignment.

  • This also confirms seat cord routing and outlet location work as intended.

• Seat power:

  • Drill a discreet hole through the decorative cover zone so the bidet seat cord passes unseen to the hidden outlet.

Service Access and Finish-Ready Protection

• Flush plate opening:

  • The “mud ring” defines the finish opening to access fill valve, flush valve, and solenoid.

  • Keep a clear, square opening.

• Protection caps:

  • Cap bowl studs, water inlet, and discharge connection with protective covers during drywall/tile to keep debris out.

• Template use:

  • Most carriers include a template that shows the precise cutout for bowl bolts, inlet, outlet, and flush plate.

  • Cutting one large opening behind the future skirt panel can expedite finish work while preserving clean lines.

Insulation and Thermal Considerations

• 2×6 cavity behind the tank provides space for continuous insulation—valuable in cold winters.

• Avoid condensation by insulating cold lines and maintaining an interior air barrier behind tile backer.

• Mark the tank zone so no fasteners penetrate during backer-board installation.

Common Pitfalls and Fixes

• Carrier face proud or shy of studs

  • Correct by adjusting leg height and drain coupling alignment; notch sill/subfloor as necessary so the face lands flush.

• No-hub bands over/under-tightened

  • Follow torque specs; retighten uniformly. If a torque wrench isn’t available, tighten carefully and recheck at inspection.

• Tight access for water adapter

  • Pre-plan with socket sizes and install the 1/2-in MIP adapter before boxing out the side blocking.

• Seat overloading a shared bathroom circuit

  • Provide a dedicated 15 A circuit to prevent nuisance trips.

• Fasteners into tank zone

  • Mark interior and exterior; use bright paint/labels; brief all trades.

Materials & Hardware Summary

• Framing: 2×6 studs and blocking, plus double 2×6 beneath window stool.

• Carrier: Powder-coated steel unit for 2×4/2×6; adjustable legs; bowl bolts; discharge parts; flush plate “mud ring.”

• Fasteners: Structural screws to side blocking; anchors for base; protective nail plates at penetrations.

• Drain: 3-in PVC riser; 4-band no-hub coupling with internal stop.

• Water: 1/2-in PEX-a line; 1/2-in MIP → PEX-a adapter; PTFE tape and approved sealant; shutoffs (carrier built-in + seat branch).

• Electrical: 120 V 15 A dedicated GFCI circuit; metal box; bonding to frame; angled plug clearance.

• Protection: Caps for bowl studs, inlet, outlet; bright marking paint.

Step-By-Step Quick Reference

1. Open framing; reposition studs to fit carrier.

2. Mark finished heights; target 18-in bowl rim AFF → set carrier top accordingly (~49 in AFF when adding 3/4-in finish floor).

3. Dry-fit carrier on a 2×4 spacer to simulate sill; lock leg screws.

4. Fit discharge; choose front bracket hole for straight down.

5. Square cut 3-in PVC; position no-hub coupling at correct slope; tighten bands uniformly.

6. Correct lean by notching sill/subfloor and wedging pipe forward as needed.

7. Install side blocking (2×6) and lag the carrier to structure; anchor feet.

8. Install water adapter; route 1/2-in PEX-a; pre-drill blocking with oversized holes; add shutoff(s).

9. Provide dedicated 15 A outlet; mount metal box to the frame; bond properly.

10. Test-hang bowl to verify height/level and power routing; then remove and cap stubs.

11. Protect openings; use template for final wall cutout; proceed to backer and tile.

12. Retain access at flush panel for all future valve service.

Finish Work and Commissioning Notes

• Tile backer and tile: Ensure the wall finish and the carrier’s front plane remain true so the bowl seats without stress.

• Flush panel: Install after tile; verify free access to fill valve, flush valve, and solenoid.

• Seat connection: Plug into the dedicated GFCI; route cord via the planned grommet.

• Final checks:

  • Pressure test water lines (carrier shutoff and seat valve).

  • Fill and test flush functions; check for any weeps at the no-hub bands and the tank inlet.

  • Confirm bowl rigidity on bolts and that rim height matches design (~18 in AFF).

FAQs

Can a wall-hung bowl be supported safely by a concealed frame?

Yes. Use a rated carrier properly anchored to blocking and floor per manufacturer’s specifications.

What if the drain alignment is off?

Adjust framing and the 3-in line. A small notch in sill/subfloor with a wedge behind the pipe lets the coupling sit square and places the carrier face flush.

Is the tank serviceable after tile?

Yes. The flush-panel opening provides access to fill/flush valves and internal components.

Does this require a wax ring?

No. The rear discharge uses a rigid connection and a coupling; follow the supplied parts and torque guidance.

Do smart seats need a dedicated circuit?

Best practice is a dedicated 15 A circuit to prevent overloads and tripping with other bathroom loads.

Integration With the Building Envelope

Marking and protecting the tank zone ensures later siding or interior finish fasteners don’t penetrate the concealed system. The earlier envelope practice—continuous sheathing integration that ties trusses to walls—remains intact because penetrations are planned, marked, and controlled. The finished bathroom gains a cleanable floor plane (no footprint pedestal), a comfortable rim height, and service access through the flush panel.

Conclusion

A wall-hung toilet with a concealed in-wall tank can be installed cleanly in 2×6 framing when the bay is prepped, the carrier height is set to match finished floor build-up, the 3-in discharge is aligned square with a correctly positioned no-hub coupling, and the water and power provisions are planned in advance. Solid blocking, dedicated electrical for a smart seat, and clear service access at the flush panel create a system that is both high-performance and maintainable. The result is a space-efficient, easy-to-clean bathroom installation with controlled penetrations and a durable finish-ready structure.