3.5 Cleanouts: Placement, Sizing, Clearances & Access Requirements
Key Takeaways
- Cleanouts are required at the upper end of horizontal drainage runs, at the junction of building drain and building sewer, where aggregate changes of direction exceed 135 degrees, at intervals not exceeding 100 feet, and at the base of stacks.
- UPC Section 707.9 requires 12 inches of clearance in front of cleanouts on piping smaller than 3 inches and 18 inches on piping 3 inches and larger.
- Cleanout size follows UPC Table 707.1; the table caps the required cleanout size for large drains rather than matching pipe size indefinitely.
- Each cleanout must open in the direction of flow or at right angles to it, and cleanout plugs may never be covered with cement, plaster, or permanent finish material.
- Cleanout plugs in floors, walkways, or traffic areas use countersunk heads so the plug sits flush with the finished surface.
Cleanouts: Placement, Sizing, Clearances & Access Requirements
Purpose of Cleanouts
A plumbing cleanout is an accessible opening in a drainage system featuring a removable plug or cap, installed to permit mechanical clearing of blockages, snake insertion, and hydro-jetting. Without properly located cleanouts, drain clearing requires cutting piping or removing fixtures.
Under UPC Section 707.0, cleanouts must be designed and positioned so that cleaning tools can reach every foot of internal horizontal drainage piping.
Mandatory Cleanout Locations (UPC Section 707.4)
Cleanouts must be installed at the following five specific locations in a sanitary drainage system:
SUMMARY OF MANDATORY CLEANOUT LOCATIONS
1. Upper End of Horizontal Run ──────► [CO] ─── (Highest Fixture Run)
2. Base of Vertical Stack ────────────► [CO] ─── (Base Stack Fitting)
3. Direction Changes > 135° ──────────► [CO] ─── (e.g., Two 90° Bends)
4. Straight Horizontal Runs ──────────► [CO] ─── (Every 100 Feet Max)
5. Building Drain / Sewer Connection ─► [CO] ─── (Inside or Outside Wall)
- Upper End of Horizontal Drainage Piping: Every horizontal drainage pipe must have a cleanout at its upper terminal end.
- Exception: Drains less than 5 feet in length measured from the stack or main line, or horizontal branches serving only one fixture (such as a lavatory) located aboveground where the trap is easily removable.
- Building Drain / Building Sewer Junction: At or near the junction of the building drain and the building sewer outside or inside the foundation wall. An exterior two-way cleanout tee is preferred.
- Changes of Direction: On horizontal drains for aggregate changes of direction exceeding 135 degrees (e.g., two 90-degree bends or a 45-degree plus 90-degree bend).
- Maximum Interval on Straight Runs: On long horizontal runs of building drains or sewers, cleanouts must be spaced at intervals not exceeding 100 feet (30.4 meters).
- Base of Vertical Stacks: At the base of every vertical soil or waste stack where it transitions into the horizontal building drain.
Sizing of Cleanouts (UPC Table 707.1)
Cleanout size is a table lookup, not a formula. UPC Table 707.1 pairs each nominal drain size with a required cleanout size. The pattern to carry into the exam room is:
- For small drains the cleanout matches the pipe size.
- Above a threshold the table caps the cleanout size, because a rodding machine cable does not need a full-diameter opening — a single cleanout size serves a range of larger drains, and very large sewers are served by manholes instead.
Open the code book and read the exact row. Tab Table 707.1 during your first pass through Chapter 7; a "what size cleanout for an X-inch drain" question is worth more time in the index than in your memory, and the numbers are among the most commonly mis-remembered in the whole code.
Two related rules that are not in the table but are frequently paired with it:
- A removable P-trap with slip or ground-joint connections can serve as the cleanout for the drain it protects, which is why a lavatory branch under 5 feet long does not need a separate cleanout.
- Where a cleanout is removed from a drainage-pattern fitting in order to extend the drain, another cleanout of equal access and capacity must be provided in the same location.
Clearance and Working Space Requirements (UPC Section 707.9)
A cleanout is useless if a plumber cannot physically insert a drain cleaning machine cable into the opening. The UPC mandates strict clear working space in front of all cleanout plugs:
MINIMUM FRONT CLEARANCE REQUIREMENTS
Cleanout Plug (smaller than 3") Cleanout Plug (3" or Larger)
┌──────────┐ ┌──────────┐
│ O │ │ O │
└────┬─────┘ └────┬─────┘
│ │
│ ◄─────── 12 Inches ───────► │ ◄─────── 18 Inches ───────►
▼ Clear Working Space ▼ Clear Working Space
- Piping smaller than 3 inches: at least 12 inches (305 mm) of clearance in front of the cleanout for rodding.
- Piping 3 inches and larger: at least 18 inches (457 mm) of clearance in front of the cleanout for rodding.
The IPC numbers — 18 inches for 6-inch and smaller and 36 inches for 8-inch and larger — are a different scheme. On an Iowa exam, answer 12 and 18.
- Under-Floor / Crawlspace Installation: Cleanouts installed under floors must extend flush with or above the finished floor, OR extend outside the exterior wall. If kept in a crawlspace, the crawlspace height must be at least 18 inches, and the cleanout must be located within 20 feet of the crawlspace access hatch.
Installation Standards, Access Panels & Plugs
Direction of Flow Alignment
Each cleanout must be installed so that it opens in the direction of flow of the soil or waste pipe or at right angles to it. Cleanout tees installed backwards (opening against flow) make snake insertion nearly impossible.
Plug Types and Traffic Areas
- Material: Plugs must be heavy-gauge brass or approved plastic (PVC/ABS) matching the piping system.
- Raised Head vs. Countersunk: Plugs in wall access covers, floor plates, driveways, walkways, or carpeted areas must have countersunk heads so the plug sits flush with the finished surface, eliminating tripping hazards and damage from foot or vehicle traffic.
- Never buried: Cleanout plugs may not be covered with cement, plaster, or any other permanent finishing material. Where a plug must be concealed, provide a covering plate or access door that permits access to the plug.
RAISED SQUARE HEAD (Basements / Exposed Pipe) COUNTERSUNK HEAD (Floors / Traffic / Flush Panels)
┌──────┐ ┌──────────┐
│ │ │ ┌────┐ │
┌────┴──────┴────┐ ┌────┴──┴────┴──┴────┐
│ THREADED │ │ THREADED │
│ PLUG BODY │ │ PLUG BODY │
└────────────────┘ └────────────────────┘
Concealed Access Doors
Cleanouts hidden behind finished drywall, plaster, or tile walls must be brought flush with the wall face or equipped with an access cover plate at least 12 x 12 inches in size.
What is the maximum allowable distance between cleanouts on a straight horizontal run of sanitary drainage pipe under the UPC?
What minimum clearance does UPC Section 707.9 require in front of a cleanout serving a 4-inch drain, and in front of one serving a 2-inch drain?
A plumber removes the cleanout plug from a drainage-pattern fitting so the drain can be extended to serve a new fixture. What does the code require?