8.1 Cleanout Sizing, Spacing & Installation Requirements

8.1 Cleanout Sizing, Spacing & Installation Requirements

Drainage systems collect grease, hair, paper and foreign objects that eventually cause stoppages. Without cleanouts, clearing them means breaking walls, cutting slabs or pulling fixtures. IPC Section 708 requires cleanouts to be located, sized and installed so rodding equipment and inspection cameras can reach the piping for the life of the building.

For the plans examiner, cleanouts are checked on floor plans, site utility plans and riser diagrams. A missing or inaccessible cleanout is cheap to fix on paper and expensive to fix in the field.

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Where Cleanouts Are Required (2024 IPC 708.1.1 through 708.1.4)

┌─────────────────────────────────────────────────────────────────────────┐
│               REQUIRED CLEANOUT LOCATIONS (IPC 708.1)                   │
├──────────────────────────────────────┬──────────────────────────────────┤
│ Location                             │ Rule                             │
├──────────────────────────────────────┼──────────────────────────────────┤
│ 1. Horizontal drains in buildings    │ Intervals of not more than 100 ft│
│ 2. Building drains                   │ 100 ft (400 ft with manholes)    │
│ 3. Building sewers under 8 in.       │ Intervals of not more than 100 ft│
│ 4. Building sewers 8 in. and larger  │ Manhole within 200 ft of junction│
│                                      │ and every 400 ft                 │
│ 5. Building drain/sewer junction     │ At junction or within 10 ft      │
│                                      │ upstream                         │
│ 6. Horizontal change > 45 degrees    │ At the change; one cleanout      │
│                                      │ serves all changes within 40 ft  │
└──────────────────────────────────────┴──────────────────────────────────┘

1. Horizontal Drains and Building Drains (708.1.1)

• Horizontal drainage pipes in buildings need cleanouts at intervals of not more than 100 feet.
• Building drains need cleanouts at intervals of not more than 100 feet, except that where manholes are used instead, they are at intervals of not more than 400 feet.
• The interval is measured from the cleanout or manhole opening along the developed length to the next fitting that gives cleaning access, or to the end of the drain.
• Exception: Horizontal fixture drain piping serving a nonremovable trap does not need a cleanout between the trap and its vent connection.

2. Building Sewers (708.1.2)

• Smaller than 8 inches: Cleanouts at intervals of not more than 100 feet.
• 8 inches and larger: A manhole not more than 200 feet from the junction of the building drain and building sewer, and at intervals of not more than 400 feet.

3. Building Drain and Building Sewer Junction (708.1.3)

The junction must be served by a cleanout at the junction or within 10 feet of developed length upstream of it. Removing a water closet does not count as cleanout access for this purpose. A two-way cleanout at the junction is a common way to rod both upstream and toward the sewer (and is an approved exception to the direction-of-flow rule in 708.1.9).

4. Changes of Direction (708.1.4)

Where a horizontal drainage pipe, building drain or building sewer changes horizontal direction by more than 45 degrees, a cleanout is installed at the change. Where more than one such change occurs within 40 feet of developed length, the cleanout installed for the first change serves all changes within that 40 feet.

What the 2024 Code Does Not Require

The 2024 IPC Section 708 does not include a separate requirement for a cleanout at the base of every stack, or at every branch junction. Base-of-stack cleanouts are common good practice and may be required by local amendment, but an exam answer should rest on the 708.1.1 through 708.1.4 locations.

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Cleanout Size (IPC 708.1.5)

Cleanouts are the same size as the piping served, except that cleanouts for piping larger than 4 inches need not be larger than 4 inches. Three exceptions apply:

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 referenced cast-iron fitting standards (Table 702.4).

Examiner Review Note: A 3-inch cleanout on a 4-inch horizontal building drain is undersized. The same 3-inch cleanout on a 4-inch stack is acceptable under Exception 2.

Cleanout equivalent (708.1.6): A fixture trap, or a fixture with an integral trap, that is removable without altering concealed piping is acceptable as a cleanout.

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Clearance and Access (IPC 708.1.10 and 708.1.11)

Required Clearance (708.1.10)

• Piping 6 inches and smaller: At least 18 inches of clearance from, and perpendicular to, the face of the opening to any obstruction.
• Piping 8 inches and larger: At least 36 inches.

             CLEANOUT CLEARANCE (IPC 708.1.10)

    +--------------------------------------------------------+
    |                     FINISHED WALL                      |
    +---------------------------+----------------------------+
                   Pipe Size    |    Clearance in Front of Opening
                   <= 6 inches  |---> Min. 18 inches (457 mm)
                   >= 8 inches  |---> Min. 36 inches (914 mm)
    +---------------------------+----------------------------+

Cleanouts Must Not Be Concealed (708.1.11)

Required cleanouts may not be installed in concealed locations, which include:

• The inside of plenums, within walls, and within floor/ceiling assemblies
• Below grade
• 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

Further rules:

• Wall cleanouts: The face of the opening must be within 1-1/2 inches of the finished wall surface.
• Below-grade cleanouts: Extended to grade so the top of the plug is at or above grade.
• Floor and walkway cleanouts: Without a trim cover, a countersunk plug is installed flush with the finished surface.
• Trim covers (708.1.11.1): Trim covers and access doors must be designed for the purpose and approved. Plugs may not be covered with mortar, plaster or other permanent material.
• Vehicle loads (708.1.11.2): Where a plug must resist vehicular traffic, a cleanout assembly complying with ASME A112.36.2M is installed.

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Construction Details, Plugs & Prohibited Practices

Direction of Cleaning (708.1.9)

The cleanout arrangement must allow cleaning of the drainage piping only in the direction of drainage flow. The exceptions are test tees serving as cleanouts and an approved two-way cleanout at the building drain/sewer junction (708.1.3). A cleanout that faces upstream lets a cable travel against the flow and is not acceptable.

Plugs and Materials (708.1.7)

• Materials: Copper-alloy, plastic or other approved materials. Copper-alloy plugs conform to ASTM A74 and are limited to metallic piping systems. Plastic plugs follow the plastic fitting standards in Table 702.4, and borosilicate glass systems use borosilicate plugs.
• Head types: A raised square head, a countersunk square head or a countersunk slot head. Where a trim cover screw threads into the plug, the plug must have a blind threaded hole.

Manholes (708.1.8)

Manholes and covers must be of an approved type, and manholes inside a building must have gas-tight covers that require tools for removal.

Prohibited Use (708.1.12)

A threaded cleanout opening may not be used to add a fixture or extend piping unless another cleanout of equal size is installed with the required access and clearance.

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Plan Examiner Review Checklist: Cleanouts

1. Junction Cleanout: Is there a cleanout at the building drain/sewer junction or within 10 feet upstream (708.1.3)?
2. Spacing: Are cleanouts at 100-foot maximum intervals on horizontal drains, building drains and building sewers under 8 inches (708.1.1, 708.1.2)?
3. Large Sewers: For sewers 8 inches and larger, is there a manhole within 200 feet of the junction and at 400-foot intervals?
4. Direction Changes: Is there a cleanout at each horizontal change over 45 degrees, with one cleanout covering all changes within 40 feet (708.1.4)?
5. Size: Do cleanouts match the pipe (not over 4 inches needed), using the P-trap, stack and cast-iron exceptions correctly (708.1.5)?
6. Clearance: Is there 18 inches in front of cleanouts on 6-inch and smaller pipe, and 36 inches on 8-inch and larger (708.1.10)?
7. Access: Are cleanouts out of plenums, walls, ceilings and low crawl spaces (less than 24 inches), and extended to grade or flush with finished surfaces (708.1.11)?