Water Closet Location and Seat Height (2010 ADA Standards 604)
The 18 in everyone remembers is a WINDOW of 16 to 18, and the plumbing code's 15 in minimum is not inside it.
Example
You enter
- Centerline from the side wall or partition (in) 15
- Seat height to the TOP of the seat (in) 16.5
- Clearance from the side wall (in; 0 = skip) 60
- Clearance from the rear wall (in; 0 = skip) 56
- Flush control side open
- Ambulatory accessible compartment? no
You get
- Centerline (16 to 18 in; 17 to 19 in an ambulatory compartment) 1
- Seat height (17 to 19 in) under by 0.50 in
- Clear area (ft²) 23.3333
- Required area (ft²) 23.3333
- Side deficit (in) 0
Checked against published worked examples from: US Department of Justice / US Access Board.
Details, formula, and sources
ScopeThe 18 in everyone remembers is a WINDOW of 16 to 18, and the plumbing code's 15 in minimum is not inside it -- so a closet roughed at the IPC minimum is code-compliant and ADA-noncompliant by an inch, while one set at a generous-looking 20 in fails the other end. The seat is 17 to 19 in to the TOP OF THE SEAT, not the rim, so a thick seat moves a compliant bowl either way. And the 60 x 56 in clearance is CLEARANCE, not a compartment: it must be clear of everything, which is why a lavatory that fits the room can still fail by standing in it.
Formula or tablecenterline 16 in minimum to 18 in maximum from the side wall or partition (17 in minimum to 19 in maximum in an ambulatory accessible compartment, 604.8.2); seat height 17 in minimum to 19 in maximum measured to the top of the seat; clearance 60 in minimum from the side wall and 56 in minimum from the rear wall; flush controls on the open side except in an ambulatory accessible compartment.
Source and edition2010 ADA Standards for Accessible Design, 604.2, 604.3.1, 604.4, and 604.6. A US federal standard in the public domain, quoted directly.
Free accessThe 2010 ADA Standards are published in full at no cost at ada.gov and by the US Access Board.
What governsEstimate. AHJ and licensed professional govern.
API field namescenterline_in, seat_height_in, clear_side_in, clear_rear_in, flush_side, ambulatory, centerline_deficit_in, seat_deficit_in, clear_area_sf, required_area_sf, side_deficit_in
- Centerline 16 in minimum to 18 in maximum from the side wall or partition; 17 to 19 in in an ambulatory accessible compartment2010 ADA Standards 604.2
- Seat height 17 in minimum to 19 in maximum, to the top of the seat2010 ADA Standards 604.4
- Clearance 60 in from the side wall, 56 in from the rear wall, clear of other fixtures2010 ADA Standards 604.3.1
- Flush controls on the open side, except in an ambulatory accessible compartment2010 ADA Standards 604.6
- Plumbing code comparison the IPC 15 in minimum is below the ADA window and is reported as suchroughlogic addition, stated