Standard Rough-In Heights and Clearances for a Bathroom

Why this matters

A rough-in is set weeks before the fixtures arrive, by someone measuring from a stud that will not be the finished face, and the mistakes show up after tile: a toilet that will not sit back against the wall, a lavatory trap that cannot reach its stub, a shower arm that puts the head at a tall customer's chin, a toilet that fails final because a vanity crowds it. Two kinds of numbers are mixed up on every job. Clearances are code: minimums an inspector measures. Heights are convention: common values that the fixture's spec sheet overrides. This card gives both, keeps them apart, and runs a tight powder room through the clearances.

The common heights

Heights below are measured from the finished floor, and are common starting values, not code. The spec sheet of the fixture or valve body actually being installed is the rule, and it should be on site before the rough-in.

 COMMON ROUGH-IN HEIGHTS, inches above finished floor
 (the fixture spec sheet overrides every one)

 |  o== shower arm  78 to 80                    |
 |                                              |
 |  [V] shower valve  45 to 48                  |
 |                          LAV                 |
 |  [V] tub valve           H o    o C          |
 |      28 to 30            supplies 20 to 22   |
 |  [=] spout, about 4      drain stub 18 to 20 |
 |      above the tub rim                 WC    |
 |__ tub rim 14 to 16 ____________ supply 6 to 8|
       TUB/SHOWER          LAV         TOILET

Toilet. The flange center is set 12 in from the finished wall, the most common rough; 10 in and 14 in roughs exist for older houses and specific bowls, and the bowl has to match. The supply stub is commonly 6 to 8 in above the floor and about 6 in to the left of the centerline as you face the wall; a one-piece or skirted bowl may want it somewhere else entirely.

Lavatory. Drain stub commonly 18 to 20 in above the floor at the fixture centerline, so the trap reaches it with the tailpiece the faucet brings. Supplies commonly 20 to 22 in above the floor, about 4 in either side of center. A vessel sink, a wall-hung lavatory or a console with an exposed trap changes all three.

Tub and tub-shower. The valve body is commonly 28 to 30 in above the floor, which on a standard tub is about a foot above the rim. The spout is commonly about 4 in above the rim, set to the spout's own required nipple length. The shower arm is commonly 78 to 80 in above the floor.

Shower only. Valve commonly 45 to 48 in above the floor, so it is reachable from outside the spray. The valve's rough-in depth inside the wall (where the body sits relative to the finished face) is set by the valve's plaster guard and the planned wall build-up; see 'Shower Valve Types and What the Rough-In Depth Depends On'.

When the common height is the wrong height

The common values assume a standard tub, a 30 to 32 in vanity and an average adult. Four situations move them, and each has to be decided before the stubs go in.

Taller vanities. Vanities at 34 to 36 in to the counter are now common. The lavatory bowl sits higher, the tailpiece ends higher, and a drain stub at 18 in sits well below the trap outlet, so the arm would have to drop to the wall (putting the vent opening below the trap weir) unless the trap is lowered on an extra-long tailpiece. Set the stub from the vanity height and the sink's spec sheet: tailpiece bottom, minus the trap's drop, gives the stub height.

Vessel and wall-hung lavatories. A vessel sink's drain comes out much higher than an undermount's; a wall-hung lavatory's trap is visible and its supplies usually want to be higher and closer together. Both need the spec sheet, and a wall-hung fixture needs blocking or a carrier set at rough-in.

The tall household. A shower arm at 78 to 80 in puts a fixed head below the chin of a tall bather. Raising the arm, or planning a slide bar or handheld, is a rough-in decision; moving an arm through finished tile is not.

Wall-hung toilets. The carrier sets the bowl height and the drain and supply locations, and the in-wall tank needs its access panel located. None of the floor-mount values above apply; the carrier maker's rough-in sheet is the only source.

The hard clearances

These are code minimums, cited from the 2021 edition of each code, as adopted by your jurisdiction.

Each figure is a minimum, measured from finished surfaces: tile face to bowl center, not stud to flange. The IPC's 21 in front clearance also applies in front of a lavatory or bidet under the same section. How a door swing counts against the front clearance, and whether a tub's apron is a side obstruction, are questions to settle with your inspector before the floor plan is fixed.

Accessible bathrooms. A bathroom required to be accessible under the building code or the ADA Standards has larger clearances and fixed heights (water closet centerline distance, grab bar backing, lavatory knee space) that replace the table above. Those come from the building code's accessibility chapter and ICC A117.1 as adopted, or from the ADA Standards where they apply, not from the plumbing code.

Measuring from the right face

Every number in this card is from a finished surface, and the rough-in is set from framing. The difference is the wall build-up, and getting it wrong is the classic flange mistake.

Toilet flange from the back wall. Flange center = rough dimension + finished wall build-up, measured from the stud face. For a 12 in rough on a wall finished with 1/2 in drywall: 12 + 1/2 = 12-1/2 in from the stud. On a wall getting 1/2 in cement board plus 3/8 in of tile and setting bed: 12 + 7/8 = 12-7/8 in from the stud. Set it at 12 in from the stud on that tiled wall and the finished rough is 11-1/8 in: most 12 in bowls will not sit back, and the tank hits the tile.

Side clearance. Same arithmetic from the side wall: 15 in finished means 15 in plus the side wall's build-up from the stud. If a vanity will stand beside the toilet, the 15 in is to the vanity's side, so the vanity width goes on the drawing before the flange goes in.

Floor. Heights are from the finished floor, so a tile floor with backer raises the finished floor by its build-up, and the lavatory drain and supplies set from the subfloor go up by the same amount.

Worked example: a powder room that almost fits

A powder room under a stair, IPC jurisdiction on one job and a UPC jurisdiction on an identical job across the county line, both 2021 editions as adopted. Finished dimensions after drywall: 32 in wide, 48 in deep, door in the wall facing the toilet. The customer has chosen an elongated bowl; the spec sheet gives its overall depth as 29-1/2 in from the finished wall at a 12 in rough. A round-front bowl from the same line is listed at 27 in deep. Both depths are as read from the spec sheets for this example; read the one for the bowl you are setting.

Side clearance. Toilet centered in a 32 in room: 32 / 2 = 16 in from center to each side wall. Required 15 in under both codes. Passes both, with 1 in to spare each side.

Front clearance, elongated bowl. 48 - 29-1/2 = 18-1/2 in clear in front. Required 21 in (IPC) or 24 in (UPC). Fails both: short by 2-1/2 in under the IPC and 5-1/2 in under the UPC.

Front clearance, round-front bowl. 48 - 27 = 21 in clear. IPC requires 21: passes exactly at the minimum. UPC requires 24: fails by 3 in.

Flange set from the stud. The back wall gets 1/2 in drywall only, so the flange center goes 12-1/2 in from the stud face for a 12 in finished rough.

What the owner hears. On the IPC job, the round-front bowl fits and the elongated does not; that is a fixture change at no cost to the room. On the UPC job, neither bowl fits a 48 in room: it needs 24 in plus the bowl depth, which is 51 in for the round-front, so the room grows 3 in or the door wall moves. Better said at the layout meeting than at final.

What would change the answer. A 10 in rough bowl, if one in the line suits the drain location, brings the bowl front 2 in closer to the wall and can turn a fail into a pass, but only where the flange is actually at 10 in from finished wall; moving a flange in a slab to get there is its own job. A pocket door instead of a swinging door changes nothing in the table but often changes the inspector's view of the space.

How to verify you got this right

• The spec sheets for every fixture and valve are on site before rough-in, and each height on the rough-in matches its sheet or the common value above where the sheet is silent.
• Every flange and stub dimension was set as finished dimension plus the planned wall or floor build-up, and the build-up is written on the layout.
• Side and front clearances were computed from finished surfaces and the actual bowl depth, against the code on the job file.
• Any accessible bathroom was laid out from the accessibility standard, not from this table.

References

• IPC 2021 Sections 405.3.1 and 421.4, as adopted by your jurisdiction.
• UPC 2021 Sections 402.5 and 408.6, as adopted by your jurisdiction.
• ICC A117.1 as adopted, or the ADA Standards where they apply, for accessible bathrooms.
• The fixture and valve maker's spec sheets and installation instructions, which are part of the listing.
• See related: Shower Valve Types and What the Rough-In Depth Depends On; How to Rough In a Toilet Drain and Closet Flange; Where the IPC and UPC Disagree on Service and Remodel Work.