Plumbing fixture rough-in and setting field guide

What rough-in is and why it has to be right the first time

A plumbing rough-in is the in-wall and in-floor piping set to the fixture before anything closes over it. The drain comes up where the trap will land, the vent ties off above, and the hot and cold supplies stub out at the height and spacing the fixture wants. All of it gets placed, tested, and inspected while the framing is open, because once the drywall, the tile, the slab pour, or the cabinet goes in, the pipe is buried.

That is the whole reason rough-in carries the weight it does. The finish trades follow you. The drywaller, the tile setter, the cabinet installer, and the flooring crew all build on top of the stub-outs you set, and they do not move them. Set the closet flange an inch off and you do not find out until the bowl will not reach the wall, and by then there is finished tile over the part you need to open. The cost of a bad rough-in is not the pipe. It is the demolition to reach the pipe.

Two documents drive the work. The rough-in drawing, the plumbing plan that locates each fixture, and the fixture cut sheet, the manufacturer's dimensioned drawing for the specific model. The plan tells you where the bathroom goes. The cut sheet tells you exactly where the drain and supplies land for that toilet, that lavatory, that tub filler. Build off the plan alone and you build off generic dimensions for a fixture that has its own. The sheet wins.

How do you read a fixture rough-in sheet?

Every fixture ships with a rough-in sheet, the manufacturer's dimensioned drawing that gives the drain location, the supply heights and spacing, and the clearances, and every one of those dimensions is taken from the finished surface, not the framing. That is the single fact that turns a clean rough-in into a callback when it gets missed. The sheet says 12 in to the flange center. It means 12 in from the finished wall, drywall or tile already on.

So you read the sheet for three things. Where the waste lands, measured off the finished wall and the centerline. Where the supplies land, their height off the finished floor and the distance between hot and cold. And the keep-out dimensions, the clearances the fixture needs to its sides and front so the trim, the handles, and the door all clear. A wall-hung or back-outlet fixture adds the connection point and, for the carrier types, the rough opening the frame needs.

The discipline is to translate every finished dimension back to the framing before you set the pipe. On a stud wall with 1/2 in drywall, the 12 in finished dimension becomes 12-1/2 in off the stud. A tile wall on a mortar bed can add an inch or more, so you carry the finish schedule, not a guess. Keep the cut sheet on site and use it as the last check before you strap the pipe, because the sheet for the model that actually got purchased is the only one that counts, and substitutions happen between the spec and the delivery.

What is the toilet rough-in dimension?

The standard toilet rough-in is 12 in from the finished wall to the center of the closet flange, with 10 in and 14 in offered for walls that sit tighter or deeper. That dimension is the one number a plumber carries for a closet, and it is measured to the finished wall surface. Set the flange center 12 in off the drywall or tile, not 12 in off the stud, or the tank ends up tight to the wall or floating off it.

On a stud wall you add the finish thickness, so a 12 in rough becomes 12-1/2 in off the framing for 1/2 in drywall, more for tile on a bed. The closet flange sits on top of the finished floor, which is its own dimension and its own failure point, covered in the next section. The side clearance matters too. Most codes require a minimum clear width at a water closet, commonly 15 in from the centerline to any wall or fixture on each side and a clear space in front. Confirm the clearances against the adopted code, because a closet jammed against a vanity fails the spacing even when the rough-in distance is perfect.

The supply stub for the toilet comes out of the wall to one side of the closet, commonly about 6 in to the left of center and about 6 to 8 in above the finished floor for a tank closet, though the tank inlet location on the cut sheet sets the real target. A wall-hung closet changes everything here, because the waste runs back through the wall to a carrier instead of down through the floor, and the rough dimensions come off the carrier's installation sheet rather than the floor flange. Pull the model's sheet and rough to it.

How high should the closet flange be?

The closet flange sits on top of the finished floor, with the flat of the flange resting on the finished surface, so the wax ring or gasket compresses against a flat plane the way it was designed to. This is the dimension that gets built wrong more than any other on a toilet, because the flange goes in during rough-in when the finished floor is not down yet, and the plumber has to set it for a floor that does not exist.

Get it too low and the wax ring cannot reach full compression. The seal weeps, slowly, and sewer gas and water find the gap under the bowl until the subfloor rots or someone smells it. Get it too high and the bowl rocks on the flange instead of bedding on the floor, and a rocking bowl works the seal loose and cracks the china at the base over time. The target is the bottom of the flange flush to the top of the finished floor, no higher and no lower.

When the finished floor goes in after the flange and leaves it sitting low, the fix is a listed flange spacer or extender that builds the flange up to the new finished height, stacked and sealed to the manufacturer's instructions. Stacking two wax rings to span the gap is the field shortcut, and it is the one that comes back, because the doubled wax is unpredictable and squeezes out under the bolts. Use the spacer made for the job. The wax ring or a waxless gasket is the seal between the bowl horn and the flange, and it only works against a flange set at the right height to a flat finished floor.

What height do you rough in a lavatory or sink?

A lavatory drain commonly roughs in near 18 to 20 in above the finished floor on the sink centerline, with the hot and cold supplies around 20 to 22 in and spaced commonly 8 in apart, hot on the left and cold on the right. Those are the everyday numbers for a standard vanity, and like every fixture dimension they trace back to the cut sheet, because a vessel sink on a tall counter or a wall-hung lav throws the heights off the standard.

The reason the drain sits where it does is the P-trap. The trap has to drop from the tailpiece, turn through its U, and run out to the wall on a slight fall to the trap arm, and the rough drain height has to leave room for all of that under the bowl without the trap hanging below the cabinet or fouling the floor of it. Rough the drain too high and the trap will not fit. Rough it too low and the trap arm has no fall. The supplies sit below the drain so the stops and the riser tubes clear the trap and reach the faucet shanks.

An accessible lavatory changes the heights and the space under it. The rim sits no higher than 34 in above the finished floor, and the rough has to leave open knee and toe clearance under the bowl, which usually means a wall-hung lav or an open-front cabinet and the drain and supplies set against the wall and insulated so a person's legs do not contact hot pipe. That accessible case has its own section. For the standard vanity, set the drain and supplies to the sheet, on the centerline, and dry-fit the trap before you close the wall.

What is a fixture carrier?

A fixture carrier is the concealed steel frame behind a wall-hung toilet, lavatory, or urinal that carries the fixture's weight and the user's load down to the floor, not into the wall. The fixture bolts to the carrier, the carrier anchors to the slab or the floor framing, and the finished wall does no structural work at all. People assume a wall-hung toilet hangs from the wall. It does not, and it must not, because a wall is not built to take a few hundred pounds cantilevered off it.

The wall-hung water closet is the clearest case. Code requires that a wall-hung closet be supported by a carrier that transmits the entire weight of the fixture and the load on it to the floor and puts no strain on the wall or the connecting piping. The carrier is a welded steel chair frame with the waste fitting built into it, set in the wall during rough-in, leveled, and bolted to the floor. The waste runs horizontally through the carrier and into the stack. The bowl studs thread into the carrier face. When someone sits on that bowl, the load goes through the studs, into the steel, and down to the floor anchors.

Lavatories, urinals, and service sinks hung off the wall use carriers too, either a concealed arm carrier that takes the load to the floor or, for lighter fixtures on a sound wall, a hanger plate rated to carry the weight without straining the pipe. The rough-in for any carrier comes off the carrier manufacturer's sheet, not the fixture sheet alone, because the carrier sets the rough opening, the waste height, and the bolt pattern. Leave the carrier out and put a wall-hung fixture on wall anchors and you have built a failure that shows up the first time it is loaded hard.

Roughing in a tub and shower

A tub and shower rough-in sets the drain at the head of the tub or the center of the shower base, the valve and the trim at their heights, and a trap and access that the finish will hide. The tub waste and overflow is the fussy part, because the trap and the waste-and-overflow assembly have to be roughed and connected before the tub is set and the floor closes, since most of it ends up unreachable once the tub is in and tiled. Dry-fit the waste-and-overflow to the actual tub before you commit the drain location.

The valve height is set for use, not by a single rule. A shower mixing valve commonly roughs in around 38 to 48 in above the finished floor depending on the user and whether it is a tub-shower or a stall, the tub spout sits a few inches above the tub rim, and the shower head drops out of the wall commonly around 76 to 80 in. Those are common ranges, and the valve manufacturer's sheet gives the rough depth from the finished wall, which matters as much as the height, because a valve set too deep behind a thick tile wall leaves the trim short and a valve too shallow leaves it standing proud. Set the valve to the finished wall plane the tile setter will build to.

The shower drain ties to a trap like any fixture, and the trap and its arm follow the venting rules covered in the DWV and venting guide. Plan an access where the code or the assembly needs one. A tub on a second floor or against a finished wall often gets an access panel behind the valve and the waste end, so a future trim or trap repair does not mean opening tile. Build the access in at rough-in. Nobody adds one later until they need it, and by then it is a demolition.

Kitchen sink, dishwasher, and disposal rough-in

A kitchen sink roughs in with the waste and supplies coming out of the wall behind the cabinet, commonly with the drain around 16 to 20 in above the finished floor and the supplies a few inches to each side of center, all of it set to clear the cabinet back and the base shelf. The exact heights bend to the cabinet and the sink, a deep apron-front sink or a bar sink change the geometry, so the rough comes off the cabinet and fixture dimensions, not a generic number. Keep the waste low enough that the disposal and the trap fit under the bowl.

The food waste disposer and the dishwasher hang off the sink drain and they each have a rule that gets missed. The dishwasher drain has to rise to a high loop fastened up under the counter, or run through an air gap fitting on the counter, so dirty sink water cannot back-siphon into the dishwasher. Many jurisdictions require the air gap and will not accept the high loop alone, so confirm which the adopted code and the inspector want before you plumb it. The disposer takes the dishwasher drain into its inlet, and that inlet plug has to be knocked out, the rookie miss that floods a kitchen on the first run.

Supplies need a stop at each riser, and the dishwasher takes its hot supply commonly off the hot stop under the sink with its own valve, so the dishwasher can be isolated without killing the sink. Rough the supplies with that extra connection in mind on the hot side. The disposer also needs power and a switch, which is the electrician's work, but the plumber coordinates the under-sink space so the trap, the disposer, the dishwasher connection, and the stops all fit without fighting each other.

Accessible and ADA fixture rough-in

Accessible fixtures rough in to a different set of dimensions and clearances, and they come from ICC A117.1 and the ADA Standards rather than the plumbing code alone, so a fixture that meets the plumbing rough-in can still fail the accessibility rough-in. The dimensions are tighter and the consequences of missing them are the same as any rough-in miss, finished work opened to move a stub-out, so they get set deliberately at rough, not adjusted at trim.

The water closet centerline sits 16 to 18 in from the side wall, not the 15 in minimum a standard closet allows, and the rough has to land the flange in that band. The seat ends up 17 to 19 in above the finished floor, which is a fixture and carrier choice more than a rough one, but the flange position is yours to set. Grab bars need solid blocking in the wall at rough-in, on the side wall and the rear wall, which is its own section, and the blocking has to be there before the wall closes because a grab bar screwed into drywall is a fall waiting to happen.

The accessible lavatory roughs in with the rim no higher than 34 in and open knee and toe clearance under it, which usually drives a wall-hung lav or an open cabinet, the drain and supplies pushed back against the wall, and the trap and supply pipe insulated or shielded so a seated user's legs do not touch hot or sharp pipe. The drain is often offset to the back wall to keep the knee space clear, which changes the waste rough from a standard vanity. A clear floor space, commonly 30 in by 48 in for a forward approach, has to be kept in front of the fixture. Verify every one of these against the adopted accessibility standard and edition, because the numbers and the scoping shift between versions and the local amendments can be stricter.

The trap and vent at each fixture

Every fixture rough-in ends in a trap, and every trap needs a vent within reach, so the rough-in is where the venting either gets done right or gets buried wrong. The drain you stub for a lavatory, a tub, or a sink is not finished until you know the trap arm from that trap to its vent stays inside the length and fall limits. Set the drain without checking the vent tie and you can pass your own eye and fail the inspector's tape.

The number that governs is the trap arm distance, the run from the trap weir to the vent fitting, which is limited by pipe size and cannot fall more than its own diameter before it reaches the vent. That limit, the vent methods, and the slope all live in the DWV and venting guide, and they are the rules that decide whether the drain you roughed will actually hold its trap seal. Rough the drain so the vent lands within the trap arm limit for the size, because moving a vent after the wall is closed is the same demolition as any other buried mistake.

On a multi-fixture wall, the rough-in is where you commit to the vent method, an individual vent, a common vent for two fixtures, or a wet vent for a bathroom group. Pick the method that the layout and the adopted code allow, set the drains and the vent connections to it, and keep the water closet downstream of the dry vent on a wet-vented group. Get the method and the trap arm right at rough and the inspection on the DWV is a formality. Get them wrong and you are opening the wall to add a vent.

The supply stub and the connection point

The supply side of the rough-in is the hot and cold stub-out at each fixture, set to the height and spacing the fixture wants and sized to deliver the flow the fixture needs at usable pressure. The stub-out is where the distribution piping you sized for the building hands off to the fixture, so it carries both the location the cut sheet dictates and the size the supply sizing demands. Those two have to agree, and the sizing is its own job, covered in the water supply and WSFU guide.

Hold the fixture supply at or above the code minimum size for the fixture type, commonly 1/2 in for a lavatory, sink, or tub and 3/8 in for some small fixtures, with a flushometer water closet needing a 1 in supply for its hard, short flush. The calculation can call for bigger on a long or busy run, and it can never go below the minimum, which the inspector checks against the fixture-supply table. Rough the stub in the right size and the right place, capped and ready for the stop at trim.

The stub-out terminates so a stop valve can land on it cleanly at the finish, which means the rough length and the wall penetration leave room for the escutcheon and the stop without the pipe fighting the cabinet or the wall. The connection point for a back-outlet or wall-hung fixture is its own dimension off the carrier or fixture sheet. Set the supplies where the trim can reach them, because a stub that lands behind a cabinet stile or too tight to the drain makes the finish plumber's stop a fight every time.

Why does the rough-in need an inspection before the wall closes?

The rough-in gets inspected and tested before any wall, floor, or ceiling covers it, because once the piping is buried, a leak or a code defect costs a demolition to reach. No covering goes over uninspected plumbing. That is enforced by the AHJ, who can stop the work, and it is the one schedule constraint the finish trades cannot push around, because the drywaller cannot legally close a wall the inspector has not signed off.

Two tests back the inspection. The DWV side gets a water test or an air test, commonly a 10 ft column of water above the highest fitting in the section held for about 15 minutes, or about 5 psi of air, while you walk every joint for a drop or a weep. Note that many jurisdictions require plastic DWV to be water-tested rather than air-tested, for safety and for a truer leak picture, so confirm the method. The water supply side gets pressurized to at least its working pressure and held, commonly for the same kind of window, watching the gauge for a fall. Confirm the methods, pressures, and durations against the adopted code and the inspector before you fill or pressurize.

The inspector checks more than the tests. The pipe material and support spacing, the trap configurations and the vent connections, the drain slope, the trap arm distances, the fixture supply sizes, and the fixture rough dimensions all get looked at while the wall is open, because this is the last time anyone can see them. Record what each test held, the section, the method, the value, and the hold time, so the rough inspection has a result behind it and not a claim. A failed rough generates a correction notice, and the work gets fixed and re-inspected before any cover goes on.

Setting the fixture, the stops, and the trim

Setting is the finish work, where the fixture goes on the rough-in you built, and it is where a clean rough either pays off or gets undone by a sloppy set. The stops come first, an angle stop or straight stop on each supply stub with an escutcheon trimming the wall penetration, then the riser tubes up to the faucet or the fixture, then the trap on the drain. Snug the stops to the stub-out, open them, and check for a weep before the cabinet fills with finish trim, because a stop that drips is far easier to fix before the trap and the supplies are in around it.

The toilet is the set that gets botched most. The bowl goes on a wax ring or a waxless gasket over the flange, dropped square onto the closet bolts and pressed straight down to compress the seal without rocking it sideways. Then the nuts on the closet bolts get snugged, alternating side to side, until the bowl is firm and level, and no further. Over-torque the closet bolts and you crack the china at the base, a crack that often does not show until it spreads and the bowl leaks weeks later. Snug, level, stop. Shim a bowl that rocks on an uneven floor and seal the base, commonly with a bead of caulk left open at the back so a future leak shows itself instead of hiding under the bowl.

The faucet, the trap, and the supply connections get made up and then leak-checked under real flow, not just snugged and trusted. Fill the trap and run the fixture, then feel every joint, the stops, the risers, the faucet shanks, the trap slip nuts, the disposer and dishwasher connections under a kitchen sink. Caulk the fixture to the wall or counter where the finish calls for it. The set is not done when the fixture is bolted down. It is done when it has run under load and held dry at every joint.

Backing and blocking in the wall

Backing, the wood or steel blocking set in the open wall at rough-in, is what gives the finish something solid to screw into, and it has to go in before the wall closes or it does not go in at all. Grab bars, wall-hung fixtures, faucets on a wall, towel bars that take real load, and the carrier anchors all need blocking, and a wall-hung anything screwed into bare drywall is a failure waiting on the first hard load.

Grab bars are the safety case and the one that gets skipped. A grab bar has to hold a falling adult, commonly a 250 lbf load the standard tests it to, and drywall anchors will not. The blocking goes in the side wall and the rear wall at the heights the accessible standard sets for the bars, wide enough to catch the bar ends wherever the trim lands, and it has to be there at rough because nobody opens a finished accessible toilet room to add wood. Coordinate the bar heights from the accessibility standard and block the whole range, not a single point.

Wall-hung fixtures on a hanger plate, wall-mount faucets, and the carrier frames all want their anchor points backed solid. The carrier mostly stands on its own floor anchors, but the trim, the actuator plate on a wall-hung closet, and any wall-mounted accessory still want blocking. The rule on every one of these is the same. If something heavy or load-bearing screws to the wall at finish, the backing for it goes in at rough, because the wall is only open once.

Coordinating the rough to the finish and the access

The rough-in only works if it is coordinated to the trades that build over it, because every fixture dimension is taken from a finished surface that other trades create. The framer sets the studs you measure off, the drywaller adds the thickness that turns your stud dimension into a finished one, the tile setter can add another inch of bed and tile, and the cabinet installer sets the box your stub-outs have to land inside. Rough to the framing alone, ignore what goes on over it, and the finished dimension drifts off the fixture sheet.

So you carry the finish schedule into the rough. Know the wall finish at each fixture, drywall or tile on a bed, and add it to the rough dimension. Know the cabinet sizes and set the kitchen and vanity stub-outs to land where the cabinet back and shelves allow a stop and a trap. Know the finished floor build-up, because that is what sets the closet flange height, and a thick tile floor poured after the flange leaves the flange low if nobody planned for it. The coordination is not paperwork. It is the difference between a stub-out the finish plumber can use and one they have to fight.

Access is part of the coordination. Where a valve, a trap, or a connection ends up behind a finished surface that the code or good practice says has to stay reachable, the access panel goes in during rough and finish planning, not after. A tub valve against a finished wall, a trap above a hard ceiling, a shutoff inside a chase, each gets an access the building keeps. Skip the access and the next repair is a hole cut in finished work, which is the cost a planned panel was meant to avoid.

Commercial versus residential rough-in

Commercial rough-in runs on the same dimensions-from-the-finished-surface rule, but the fixtures and the scale change the work. Residential closets are tank type on a floor flange, residential lavs sit on a vanity, and the runs are short. Commercial work leans on flushometer valves instead of tanks, wall-hung fixtures on carriers instead of floor-set, and batteries of identical fixtures ganged on a common wall, which turns the rough-in into a repeated, gridded layout where one wrong dimension repeats down the whole row.

The flushometer is the first difference that reaches back into the rough. A flushometer water closet flushes directly from the supply in a hard, short burst, so it needs a 1 in supply where a tank closet gets by on 3/8 in or 1/2 in, and it needs a higher residual pressure to operate, which the supply sizing has to carry. Rough the supply for the flush valve, not the tank, or the valves on the upper floors or the far end of the run will not snap through their cycle. The flush valve also roughs in at a set height above the fixture, off its own sheet.

The carrier is the second difference, and on a commercial restroom it is most of the rough-in. Wall-hung closets, urinals, and lavatories all stand on carriers set in a chase wall, leveled and anchored to the floor, with the waste and the supplies roughed to the carrier sheets. A battery of fixtures means a battery of carriers, set to a common centerline and a repeated spacing, all tied to a horizontal waste line and a vent in the chase. Set the grid right once and the row goes clean. Set the first carrier off and the error walks down every fixture in the line.

Data center and large commercial restroom batteries

A large commercial restroom or a data center support floor roughs in as a battery, a row of identical fixtures on a common chase wall, and the rough-in becomes a layout problem as much as a piping one. The carriers set to a single centerline and a repeated fixture spacing, the waste runs as a horizontal branch picking up each fixture in order, and the vent ties the row together in the chase. The work is gridded and repetitive, and the discipline is to prove the first fixture's dimensions against the fixture and carrier sheets, then hold that grid exactly down the line.

The chase wall is what makes the battery serviceable. A back-to-back restroom layout or a dedicated pipe chase puts the carriers, the waste, the supplies, and the vents in a space a tech can enter, so a flushometer rebuild or a carrier repair does not mean opening the finished restroom. Rough the battery into the chase with that access in mind, because a commercial restroom that gets heavy public use will need service, and a battery built with no access turns every repair into finished-wall demolition.

On a data center the restroom load is small next to the building's mission, but the same rough-in rules hold, and the coordination is tighter because the building runs around uptime. The domestic fixtures rough in conventionally, while the large mechanical water loads, the makeup for humidification and for evaporative or adiabatic cooling, are their own piping with their own backflow protection, sized off the project documents rather than the fixture-unit method. Keep the potable fixture rough-in clean and separate from the mechanical makeup piping, and coordinate both against the project specifications, because on a critical building the design is engineered and stamped and the field follows it.

What to document

Every measurement set at rough-in vanishes once the wall closes, leaving the written record as the only account of where the stubs, the drain, and the trap arm actually landed. The record is what proves each fixture was roughed to its sheet, off the finished surfaces, and tested before cover, and it is what the next plumber reads when a fixture leaks or a remodel reopens the wall.

Capture, for each fixture, the rough-in dimensions you set and the surface you measured from, the supply heights and sizes, the drain and vent location with the trap arm against its limit, the carrier model where there is one, and the test that backed the rough. Record which code and edition you worked to, because the minimums and clearances only mean something tied to the code that produced them, and record the accessibility standard where an accessible fixture is involved. Tie the record to the fixture cut sheet, since the sheet is the dimension authority and the record proves you built to it.

Common mistakes

• Measuring the rough from the framing instead of the finished wall, so the fixture sets too close or too far once the finish is on.
• Setting the closet flange below the finished floor, so the wax ring cannot compress and the seal leaks while the bowl rocks.
• Setting the closet flange too high, so the bowl rocks on the flange instead of bedding on the floor and cracks at the base.
• Hanging a wall-hung toilet, lav, or urinal on wall anchors with no carrier to take the load to the floor.
• Roughing the lavatory supplies and drain at the wrong height or spacing, so the trap will not fit or the stops fight the cabinet.
• Leaving out the in-wall blocking for a grab bar or a wall-hung fixture, so the finish has only drywall to grab.
• Closing the wall before the rough inspection and the DWV and supply tests, which the AHJ will make you reopen.
• Over-torquing the closet bolts at the set and cracking the china, or stacking two wax rings instead of using a listed flange spacer.

Field checklist

Standards and references

The framework lives in the two model plumbing codes, and the adopted edition with local amendments controls. The IPC, published by the ICC, and the UPC, published by IAPMO, set the fixture requirements, the trap and vent rules, the fixture supply minimums, the access requirements, and the rough-in tests in their fixtures, sanitary drainage, vents, and water distribution chapters. The section and table numbers shift between editions, so confirm them against the edition the jurisdiction enforces before citing one on a permit set.

The fixture manufacturer's rough-in sheet governs the actual dimensions, and it overrides any generic number in this guide, because it is drawn for the specific model and its dimensions are taken from the finished surfaces. ASME A112 standards cover the plumbing fixtures and fittings themselves, the china, the flush valves, the supply stops, and the closet flanges, and a fixture listed to its ASME standard is what the code expects you to install. Accessibility comes from ICC A117.1 and the ADA Standards for Accessible Design, which set the heights, clearances, and grab bar requirements for accessible fixtures, and the adopted accessibility standard and edition control there the same way the plumbing code does.

The AHJ is the other governing party, because the inspector enforces the adopted code, runs the rough inspection, and accepts or rejects the tests. Cite the standard that controls the point, confirm the dimensions against the fixture and carrier sheets, and let the project specifications and the adopted code override any rule of thumb in this guide.

Units and terms

Rough-in work carries its own vocabulary, and the same part shows up under different names across a plan set, a cut sheet, and a supply-house counter.

Fixture dimensions are given in inches, taken from the finished wall and finished floor. The toilet rough-in is the distance from the finished wall to the flange center. Supply and drain heights are measured off the finished floor. The terms below are the ones a plumber and an inspector use to talk about the same parts of a rough-in and a set without crossing wires.

Rough-in

The drain, vent, and supply piping set to a fixture in the open wall and floor, tested and inspected before the surfaces close

Rough-in sheet / cut sheet

The manufacturer's dimensioned drawing for a fixture, giving drain, supply, and clearance dimensions from the finished surfaces

Toilet rough-in

The distance from the finished wall to the center of the closet flange, commonly 12 in, with 10 in and 14 in alternates

Closet flange

The fitting that connects the toilet to the drain, set on top of the finished floor to seat the wax ring or gasket

Wax ring / gasket

The seal between the toilet bowl horn and the closet flange, compressed when the bowl is set and bolted down

Fixture carrier

The concealed steel frame that supports a wall-hung fixture and carries its load to the floor, not the wall

Stub-out

The capped end of a supply or drain pipe roughed to the fixture, where the stop or trap connects at finish

Angle stop

The shutoff valve on a fixture supply stub-out, trimmed with an escutcheon, that isolates the fixture for service

Trap arm

The drain pipe from the trap weir to the vent, limited in length and fall, covered in the DWV and venting guide

Blocking / backing

Wood or steel set in the open wall at rough-in to give grab bars and wall-hung fixtures something solid to anchor to

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