708.1.11 Prohibited use.

The use of a threaded cleanout opening to add a fixture or to extend piping shall be prohibited except where another cleanout of equal size is installed with the required access and clearance.

708.1.12 Base of stack.

A cleanout shall be provided at the base of each waste or soil stack.

Section PC 709: Fixture Units

709.1 Values for fixtures.

Drainage fixture unit values as given in Table 709.1 designate the relative load weight of different kinds of fixtures that shall be employed in estimating the total load carried by a soil or waste pipe, and shall be used in connection with Tables 710.1(1) and 710.1(2) of sizes for soil, waste and vent pipes for which the permissible load is given in terms of fixture units.

Table 709.1
Drainage Fixture Units for Fixtures and Groups

Fixture Type	Drainage Fixture Unit Value as Load Factors	Minimum Size of Trap (inches)
Automatic clothes washers, commercial a, g	3	2
Automatic clothes washers, residential g	2	2
Bathroom group as defined in Section 202  f	5	–
Bathtub b (with or without overhead shower or whirlpool attachments)	2	1 1/2
Bidet	1	1 1/4
Combination sink and tray	2	1 1/2
Dental lavatory	1	1 1/4
Dental unit or cuspidor	1	1 1/4
Dishwashing machine c , domestic	2	1 1/2
Drinking fountain	1/2	1 1/4
Emergency floor drain	0	2
Floor drains	2 h	3
Floor sinks	Note h	2
Hand wash sinks and lavatories (circular or multiple) each faucet	2	1 1/2
Kitchen sink, domestic	2	2
Kitchen sink, domestic with food waste disposer and/or dishwasher	2	2
Laundry tray (1 or 2 compartments)	2	2
Lavatory	1	1 1/4
Multiple (gang) shower (based on the total flow rate through shower heads and body sprays) Flow rate:
5.7 gpm or less	2	2
Greater than 5.7 gpm to 12.3 gpm	3	2
Greater than 12.3 gpm to 25.8 gpm	5	3
Greater than 25.8 gpm to 55.6 gpm	6	4
Shower	2	2
Sink	2	2
Urinal	4	Note d
Urinal, 1 gallon per flush or less	2 e	Note d
Urinal, nonwater supplied	1/2	Note d
Water closet, flushometer, tank, public or private	4 e	Note d

 

For SI: 1 inch = 25.4 mm, 1 gallon = 3.785 L, gpf = gallon per flushing cycle, gpm = gallon per minute.

a.   For traps larger than 3 inches, use Table 709.2.

b.   A showerhead over a bathtub or whirlpool bathtub attachment does not increase the drainage fixture unit value.

c.   See Sections 709.2 through 709.4.1 for methods of computing unit value of fixtures not listed in this table or for rating of devices with intermittent flows.

d.   Trap size shall be consistent with the fixture outlet size.

e.   For the purpose of computing loads on building drains and sewers, water closets and urinals shall not be rated at a lower drainage fixture unit unless the lower values are confirmed by testing.

f.   For fixtures added to a bathroom group, add the dfu value of those additional fixtures to the bathroom group fixture count.

g.   See Section 406.3 for sizing requirements for fixture drain, branch drain and drainage stack for an automatic clothes washer standpipe.

h.   See Sections 709.4 and 709.4.1.

709.2 Fixtures not listed in Table 709.1 .

Fixtures not listed in Table 709.1 shall have a drainage fixture unit load based on the outlet size of the fixture in accordance with Table 709.2. The minimum trap size for unlisted fixtures shall be the size of the drainage outlet but not less than 1 1/4 inches (32 mm).

Table 709.2
Drainage Fixture Units for Fixture Drains or Traps

 

Fixture Drain or Trap Size (inches)	Drainage Fixture Unit Value
1 1/4	1
1 1/2	2
2	3
2 1/2	4
3	5
4	6

 

For SI: 1 inch = 25.4 mm.

709.3 Values for continuous and semicontinuous flow.

Drainage fixture unit values for continuous and semicontinuous flow into a drainage system shall be computed on the basis that 1 gpm (0.06 L/s) of flow is equivalent to two fixture units.