7.1 Fixture Construction, Clearances, Shower Size & Safing
Key Takeaways
A water closet, urinal or bidet centerline must be at least 15 inches from any side wall, partition, vanity or obstruction; water closets and urinals are at least 30 inches center to center.
A water closet needs at least 24 inches of clearance in front to any wall, fixture or door (SPS 384.20 (5) (o) 4.).
Shower compartments need at least 900 square inches of finished interior and must enclose a 30-inch circle, or a 25-inch circle with at least 1,300 square inches.
Site-built shower floors need safing up the sides at least 6 inches above the curb, and to 6 feet high at the corners; floor drains need safing extending 12 inches.
Water closets required in public buildings must be elongated with open-front seats without covers (or continuous-sleeve closed seats).
Design and material rules (SPS 384.20 (1), (2) and (4))
All fixtures, appliances and equipment must be durable, free from defects and concealed fouling surfaces, and easy to clean. They must also prevent nonpotable liquids, solids or gases from entering the potable supply. Fixture surfaces must be smooth and impervious to water. End-point drinking water fittings must meet NSF/ANSI/CAN 61, section 9.
Installation requirements (SPS 384.20 (4) (b)):
| Topic | Requirement |
|---|---|
| Access | Fixtures installed for easy cleaning of the fixture and the area around it |
| Wall-mounted fixtures | Supported by a hanger fastened to structure so no load goes onto the drain connection; floor-affixed supports meet ASME A112.6.1M, framing-affixed carriers meet ASME A112.6.2 |
| Outlet joint | Fixture outlet connection to the drain must be air- and watertight |
| Overflows | Designed so water can't rise in the overflow with the stopper closed and doesn't stand in it when the fixture is empty; overflows discharge on the inlet side of the trap |
| Flush tank overflows | Discharge to the fixture served; sized to prevent flooding at the maximum supply rate |
| Strainers | All fixtures except water closets, clinic sinks, flushing-rim service sinks, urinals, standpipes and waste sinks need strainers, crossbars or pop-up stoppers |
| Flushometer valves | Equipped with ASSE 1001 vacuum breakers; complete the cycle automatically; have a flow regulating means; not used where pressure is inadequate |
Clearances
| Fixture | Side clearance (centerline to wall, partition, vanity or obstruction) | Center to center | Front |
|---|---|---|---|
| Water closet | 15 inches | 30 inches between water closets | 24 inches to any wall, fixture or door |
| Urinal | 15 inches | 30 inches between urinals | - |
| Bidet | 15 inches | 30 inches from a water closet | - |
Worked example. A two-closet restroom is being laid out in a 60-inch-wide alcove. Each closet needs 15 inches to a side wall and 30 inches to the next closet: 15 + 30 + 15 = 60 inches, so it fits exactly. Then check the front clearance: the door swing must leave at least 24 inches in front of each bowl.
Shower compartments (SPS 384.20 (5) (L))
| Requirement | Value |
|---|---|
| Minimum finished interior area | 900 square inches |
| Minimum inscribed circle | 30 inches |
| Alternative | A 25-inch circle if the area is at least 1,300 square inches |
| Measured | In a horizontal plane 24 inches above the top of the threshold, not past the threshold centerline |
| Maintained up to | 70 inches above the waste outlet, with only valves, heads, soap dishes, retractable seats and grab bars protruding |
| Waste outlet | At least 2 inches with a removable strainer (except tub-shower units) |
| Multiple heads or spaces on one outlet | 2-inch outlet located, and floor pitched, so water from one shower doesn't cross another's floor area |
A 30 x 30 inch shower has exactly 900 square inches and holds a 30-inch circle, so it complies. A 32 x 28 inch shower has 896 square inches and won't hold a 30-inch circle, so it fails.
Safing (SPS 384.20 (4) (b) 9.)
- Floors of site-constructed shower stalls and shower rooms are protected by safing under the entire finished floor, turned up the sides at least 6 inches above the curb or maximum water level.
- Corners are safed to 6 feet high and at least 3 inches in each direction from the corner.
- Floor drains and similar fixtures need safing extending at least 12 inches from the fixture.
- Safing must meet SPS 384.30 (6) and be properly drained. Installations directly over unexcavated ground are exempt. Elevator threshold drains are also exempt.
Fixture-by-fixture requirements (SPS 384.20 (5))
| Fixture | Key rules |
|---|---|
| Bathtubs | Waste and overflow at least 1-1/2 inches with a closing device; whirlpool piping and pump waterways drain by gravity to the tub trap |
| Drinking fountains | Not in toilet rooms; adjustable valve with loose key or self-closing valve; waste outlet at least 1-1/4 inches |
| Floor and trench drains | Removable strainers; outlet at least 2 inches; ASME A112.6.3 |
| Laundry trays | Each compartment outlet at least 1-1/2 inches |
| Lavatories | Waste outlet at least 1-1/4 inches |
| Sinks | Waste outlet at least 1-1/2 inches |
| Urinals | Stall urinals set into a pitched floor; automatic siphon flush tanks prohibited; pressurized flushing devices ASSE 1037 |
| Water closets | One flushing device each; anti-siphon fill valve (ASSE 1002) with critical level at least 1 inch above the overflow pipe opening; pressurized flushing devices ASSE 1037 |
Water closets in public buildings and places of employment must be elongated with either a hinged open-front seat without cover, or a hinged closed-front seat without cover in a continuous plastic sleeve. Day care centers, individual living or sleeping units may use round bowls with closed-front seats, with or without covers. Prisons may use round bowls with or without seats.
Prohibited water closets: pan, plunger, offset washout, washout, long hopper, frostproof, and any type with invisible seals, unventilated spaces or walls not fully cleansed at each flush.
Where toilet-room counts and accessibility live
The plumbing code doesn't set the number of fixtures required or accessibility dimensions. A note to SPS 384.20 (4) points to the commercial building code (chs. SPS 361 to 366) and the pool code (ch. SPS 390) for fixture counts, compartments, toilet room finishes and facilities for people with disabilities. Those chapters are not on the journeyman exam's permitted reference list.
What is the minimum distance from the centerline of a water closet to a side partition under SPS 384.20 (5) (o) 4.?
12 inches
18 inches
15 inches
21 inches
Which shower compartment meets the minimum size in SPS 384.20 (5) (L)?
30 x 30 inches, holding a 30-inch circle
32 x 28 inches
36 x 24 inches
A 28-inch circle with 1,000 square inches
How far must safing extend around a floor drain under SPS 384.20 (4) (b) 9.?
6 inches
18 inches
3 inches
12 inches
Sections you finish are checked off in the contents.