5.2 Cleanouts: Required Locations, Size, Arrangement, Clearance & Access

Why this section matters

Every drainage system eventually needs to be rodded. Section 708 of the 2021 IPC decides where cleanouts go and how they must be arranged, and it appears in Drain Waste and Vents and plan-reading questions. Many older study materials quote earlier editions, with base-of-stack cleanouts, 12- and 18-inch clearances and "perpendicular" openings. The 2021 text is different, so read it from your book.

Where cleanouts are required

The 2021 IPC has no general requirement for a cleanout at the base of every stack. A stack-base cleanout is still common practice and often helps meet the 100-foot rule.

Size (708.1.5)

Cleanouts are the same size as the piping they serve, except that cleanouts for piping larger than 4 inches need not be larger than 4 inches. Exceptions:

1. A removable P-trap with slip or ground joints can serve as the cleanout for drain piping one size larger than the trap.
2. Cleanouts on stacks may be one size smaller than the stack.
3. Cleanouts for cast-iron piping may follow the cast-iron fitting standards in Table 702.4.

708.1.6, cleanout equivalent: A fixture trap, or a fixture with an integral trap, that can be removed without altering concealed piping counts as a cleanout.

Plugs and manholes

• 708.1.7, plugs: Plugs are copper alloy, plastic or other approved material.
  • Copper-alloy plugs conform to ASTM A74 and may be used only on metallic piping.
  • Plastic plugs conform to the plastic fitting standards in Table 702.4.
  • Borosilicate glass systems use glass plugs.
  • Plugs must have a raised square head, countersunk square head or countersunk slot head. A plug that takes a trim-cover screw must have a blind-end threaded hole for it.
• 708.1.8, manholes: Manholes and covers must be an approved type. Manholes inside a building need gastight covers that require tools to remove.

Arrangement, clearance and access

• 708.1.9: A cleanout must be arranged so the piping can be cleaned only in the direction of flow. Exceptions are test tees used as cleanouts and an approved two-way cleanout at the building drain and sewer junction.
• 708.1.10, clearance measured perpendicular to the face of the opening:

• 708.1.11, access: Required cleanouts may not be in concealed locations. Concealed locations include plenums, the inside of walls, floor-ceiling assemblies, below grade, and crawl spaces where the height from the crawl-space floor to the nearest obstruction, along the path from the crawl-space opening to the cleanout, is less than 24 inches.
  • A cleanout opening at a finished wall must have its face within 1-1/2 inches of the wall surface.
  • Cleanouts below grade must be extended to grade, with the top of the plug at or above grade.
  • In a floor or walkway with no trim cover, use a countersunk plug flush with the surface.
• 708.1.11.1: Trim covers and access doors must be approved and designed for the purpose. Never cover plugs with mortar or plaster.
• 708.1.11.2: Where vehicles may pass over a cleanout, use an ASME A112.36.2M floor cleanout assembly.
• 708.1.12: A threaded cleanout opening may not be used to add a fixture or extend piping unless another cleanout of equal size, with the required access and clearance, is installed.

Worked layout

A 4-inch building drain runs 160 feet straight from a rear stack, turns 90 degrees, and runs 30 feet to the exterior wall, where it becomes the building sewer.

1. Junction (708.1.3): a two-way cleanout at the wall, or within 10 feet upstream.
2. The 90-degree turn (708.1.4): a cleanout at the turn, 30 feet upstream of the junction.
3. The 160-foot straight run (708.1.1): from the cleanout at the turn, the next access must be within 100 feet. Place a cleanout at about the 60-foot mark from the stack (100 feet upstream of the turn). The remaining 60 feet to the end of the drain is within the limit.
4. Size: each is 4 inches (same as the pipe). Each needs 18 inches of clearance and must not be concealed. Floor cleanouts are flush, and traffic areas get an ASME A112.36.2M assembly.

A cleanout at the stack base would also be acceptable, and it shortens the rodding distance.

Exam traps

• 100 feet for drains and small sewers. 400 feet for manholes. 200 feet from the junction to the first manhole on large sewers.
• Clearance is 18 inches for 6 inches and smaller and 36 inches for 8 inches and larger. The code no longer uses a 3-inch dividing line.
• Direction of flow only, except test tees and an approved two-way junction cleanout.
• 4-inch maximum size is required for large pipe.