Wall-Hung Fixture and Carrier Installation

Purpose

A wall-hung fixture hangs off a steel carrier bolted to the structural floor. The wall carries nothing, the tile carries nothing, and the caulk line carries nothing. Everything this procedure guarantees follows from that: the carrier is anchored to structure, every governing dimension is set from the FINISHED floor and the FINISHED wall rather than from the substrate, and the assembly is load tested before anybody sits on it. The failure it prevents is the one nobody can fix afterward, a carrier set to the studs and then buried behind tile, which leaves the fixture standing proud of the wall on a gasket that never fully compresses and a joint that works a little more every day.

Scope

Covers setting concealed floor-affixed carriers and hanging wall-hung water closets, urinals and lavatories in small commercial, retail and multifamily restrooms, in new chase work and in retrofit, through to load test and return to service.

Does not cover the structural adequacy of the floor or wall framing, which is an engineering question; where the anchor substrate is in doubt this procedure stops and routes it. Does not cover flush valve work, owned by the flushometer rebuild and adjustment SOP, or accessible-layout design and permitting, which is drawn before the shop arrives.

Roles and responsibilities

Procedure

1. Get the finished floor and finished wall build-up in writing before anything is set. Acceptance: a number in inches for each layer over the substrate, from the finish schedule or the contractor in a message you can keep. Wrong looks like a build-up taken from what the tech expects, which is where a whole install goes wrong in one number. Stop rule: no confirmed build-up means no carrier goes down; set nothing on a verbal. Hazard: none at this step, it is a document, and it is the cheapest place in the job to be wrong.

2. Open the chase without disturbing material you have not identified. Acceptance: the chase open to the structural floor and the framing on both sides of the carrier location, with the wall finish identified. Wrong looks like cutting into a pre-1980 wall finish on the assumption it is ordinary board. Stop rule: presume older joint compound, plaster and resilient flooring to be asbestos-containing until sampled by a qualified inspector; if it has not been sampled, stop and route it rather than cutting. Hazard: this is an inhalation route and a respirator is the wrong first answer, the right one is not making the dust, so wet methods, a HEPA-filtered vacuum at the cut, and any respiratory protection only under a written program per 29 CFR 1910.134.

3. Set the two governing heights from the fixture's own rough-in sheet and the accessibility dimensions, and write them on the framing. Acceptance: waste centerline height above finished floor computed from the sheet and the target seat or rim height, marked, and cross-checked against the applicable accessible dimensions, which for a water closet seat is 17 in to 19 in above the finish floor at 604.4 of the 2010 ADA Standards and for a urinal rim is 17 in maximum at 605.2. Wrong looks like copying a height off the last job, because bowls differ. Stop rule: where the sheet's geometry cannot produce a compliant seat height on this floor, that is a fixture selection problem for the lead before anything is drilled. Hazard: none at this step, it is layout, and doing it after the carrier is anchored costs a set of anchors.

4. Anchor the carrier feet to the structural floor with the manufacturer's specified fasteners. Acceptance: every foot bearing on the slab or the structural deck, all fasteners in and torqued per the carrier instruction, no shims taking load. Wrong looks like anchors into a topping slab or into a plywood underlayment, which pulls out under exactly the load the carrier exists to resist. Stop rule: if you cannot reach structure, stop and route it to the lead for a structural answer rather than adding fasteners until it feels solid. Hazard: drilling into concrete or masonry releases respirable crystalline silica, so use an integrated water feed or a dust-collection shroud with a HEPA vacuum as OSHA's Table 1 at 29 CFR 1926.1153 describes for the equipment you are using, and do not dry-drill it and sweep afterward.

5. Set the waste nipple projection to the finished wall plane, not to the stud face. Stack spacers equal to the confirmed build-up against the framing and set the nipple against that stack. Acceptance: the carrier's fixture face landing within 1/8 in of the future finished wall plane, measured with a straightedge across the studs and the spacer stack. Wrong looks like a face set to bare studs, which leaves the fixture standing off the wall by the whole thickness of the finish. Stop rule: outside 1/8 in, adjust or fit the manufacturer's extension now, because after the wall closes the only fix is demolition. Hazard: none at this step beyond the tool in your hand, but this is the single dimension that decides whether the job works.

6. Connect waste and vent, then test the DWV before anything closes. Acceptance: the test your adopted code requires held for its stated duration with no drop, water or air per IPC Section 312 in the edition your authority having jurisdiction enforces. Wrong looks like a test skipped because the joints looked good, on a joint that will be behind tile. Stop rule: any drop means the joint is found and remade, not re-tested harder. Hazard: an air test stores real energy behind a plug, so nobody stands in line with a test plug or a cleanout while the system is under test, the gauge is watched from the side, and the system is bled down before a plug is touched.

7. Rough the supply and the stop, then hold the close-in inspection and record the dimensions. Acceptance: supply and stop located per the flush valve or faucet rough-in, the inspection passed where one is required, and the finished measurements written down before the wall closes. Wrong looks like a wall closed on the strength of the tech's own look. Stop rule: no wall closes ahead of the inspection, whatever the schedule pressure, because the cost of opening it again lands on the shop that closed it. Hazard: soldering inside a stud bay means shielding the framing and holding a fire watch after the last heat per NFPA 51B in the edition your authority having jurisdiction or your insurer requires, and ventilating rather than working over heated flux.

8. Hang the fixture on the correct gasket and hardware, with two people on it. Acceptance: the fixture flat to the finished wall, the waste gasket compressed as the manufacturer describes, and the mounting nuts brought up evenly to the stated value or, where none is given, until the fixture is firm with no gap and no further travel. Wrong looks like one nut pulled tight to close a gap the carrier setting should have closed, which is how china cracks weeks later. Stop rule: any gap between fixture and wall sends you back to step 5; do not close it with hardware or with caulk. Hazard: a china closet is a two-person lift and it breaks into edged pieces, so keep hands and feet out from under it, set it on padding rather than on the floor, and never use plumber's putty as a gasket where the manufacturer specifies one.

9. Load test the assembly, then leak test it, and only then return it to service. Apply the static load the carrier manufacturer states at the front rim, commonly cited around 500 lbf and confirmed against that carrier's own listing under ASME A112.6.1M in the edition your adopted code references, and hold it. Acceptance: no perceptible movement at the fixture-to-wall joint under load, no movement after release, and no weep at the waste or supply through a full flush cycle and five minutes at rest. Wrong looks like a hand pressed on the rim called a load test. Stop rule: any movement takes the fixture off and sends you back to step 4; nothing about a loose carrier improves with use. Hazard: this is the step that puts weight and pressure back with people around, so apply the load with sandbags or a proper test weight rather than by standing on it, keep everyone out of the fall line, and confirm the stop and supply hold after the load comes off.

The record this produces

Per fixture: carrier make and model, the confirmed floor and wall build-up, the waste centerline height above finished floor, the seat or rim height achieved, the anchor substrate and fastener used, the DWV test type and result, the load test value applied and the movement result, and the close-in inspection reference.

These land on the property and job record. The next tech reads the seat height and the carrier model before ordering a replacement bowl, because a different bowl on the same carrier changes the seat height. The lead reads the anchor substrate line when a fixture loosens, since a carrier anchored to a topping slab is a different repair from a relaxed nut. The property reads the load test result, which is the only evidence that the fixture was proven before it was used.

One worked pass, including a failure

Retrofit of two wall-hung closets in an existing office restroom, slab on grade, new tile going over the slab and the wall board.

Step 1 returns the build-up in a message from the contractor: floor gets 1/4 in thinset plus 3/8 in tile, so 5/8 in over the slab; wall gets 5/8 in board plus 1/8 in thinset plus 3/8 in tile, so 1-1/8 in over the studs. Step 2 finds the chase already open from a previous demolition, board identified as modern, no sampling needed.

Step 3 reads the bowl's rough-in sheet on site: 11-1/2 in from waste outlet centerline to the top of the bowl rim, and the seat adds 3/4 in. Targeting the middle of the ADA range at 18 in, the waste centerline lands at 18 minus 11.5 minus 0.75, which is 5.75 in above the finished floor. The finished floor sits 5/8 in over the slab, so above the slab the mark is 5.75 plus 0.625, or 6-3/8 in. Both marks go on the framing.

Step 5 fails. The carrier was set with its face against the stud line because the first tech worked from the old wall, and the confirmed build-up is 1-1/8 in. The face therefore sits 1.125 minus 0.625, or 0.5 in behind the finished wall plane, using only the board thickness that was allowed for. That is 0.5 minus the 0.125 tolerance, so 3/8 in outside acceptance. Stop rule taken: the manufacturer's nipple extension goes in before the wall closes, and the straightedge check is repeated, landing within 1/16 in.

Step 6 holds the water test with no drop. Step 7 passes close-in and the numbers go on the record. Step 8 hangs both bowls, gaskets compressed, no gap at either. Step 9 applies the carrier's stated test load at the front rim of each, no movement under load or after release, no weep through three flush cycles and five minutes at rest. Final seat height measures 18 in on both.

References

• ASME A112.6.1M, floor-affixed supports for off-the-floor plumbing fixtures, a consensus standard reaching you through the plumbing code your authority having jurisdiction has adopted, in the edition it names; the carrier's own listing gives the load rating you test to.
• 2010 ADA Standards for Accessible Design, 604.4 for water closet seat height and 605.2 for urinal rim height, where the facility is covered.
• IPC Section 312 for DWV testing, and 29 CFR 1926.1153 Table 1 for silica controls when drilling concrete, plus NFPA 51B for hot work in the edition your jurisdiction or insurer requires.
• Fixture and carrier manufacturer rough-in sheets, which govern every dimension in this procedure.
• See related: the Plumbing commercial restroom preventive visit SOP, whose load test flags fixtures back into this procedure.