4.3 Cleanouts: Sizing, Clearances, & Locations

4.3 Cleanouts: Sizing, Clearances, & Locations

A sanitary drainage system is only as reliable as its accessibility for maintenance. Over time, drain lines inevitably experience stoppages caused by grease buildup, foreign objects, tree root intrusion, and scale accumulation. Cleanouts provide dedicated, sealed access points for mechanical sewer machines, drain cameras, and hydro-jetting equipment without requiring the removal of fixtures or cutting into structural walls.

The Texas State Board of Plumbing Examiners (TSBPE) heavily tests cleanout sizing, allowable directional fittings, clearance distances, and interval spacing on both the written exam and the practical blueprint stations.

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1. Cleanout Sizing Rules

Cleanout sizing follows a simple two-tier rule designed to accommodate standard drain cleaning cable heads and blades while keeping fitting profiles manageable.

+-----------------------------------------------------------------------------+
|                          CLEANOUT SIZING FORMULA                            |
|                                                                             |
|   PIPE DIAMETER <= 4 INCHES:                                                |
|   - Cleanout Size MUST EQUAL Full Pipe Size.                                |
|     * 1-1/2" Pipe  --->  1-1/2" Cleanout                                    |
|     * 2" Pipe      --->  2" Cleanout                                        |
|     * 3" Pipe      --->  3" Cleanout                                        |
|     * 4" Pipe      --->  4" Cleanout                                        |
|                                                                             |
|   PIPE DIAMETER > 4 INCHES:                                                 |
|   - Cleanout Size is a MINIMUM of 4 INCHES.                                 |
|     * 6" Pipe      --->  4" Cleanout Minimum (6" permitted)                 |
|     * 8" Pipe      --->  4" Cleanout Minimum (4" or 6" typical)             |
+-----------------------------------------------------------------------------+

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2. Mandatory Cleanout Locations

Plumbing codes require cleanouts at strategic points where stoppages are most likely to form or where access is necessary to reach extended piping sections.

[ROOF TERMINAL]
       |
       |  SOIL/WASTE STACK
       |
       +---- [Fixture Branch]
       |
       |
+======+=======================+ <--- 1. BASE OF EVERY STACK
| (CO) Base of Stack Cleanout  |
+======+=======================+
       | 
       v
[BUILDING DRAIN] -------> [CHANGE OF DIR > 45°] -------> [100-FT RUN] -------> [TO SEWER]
                                | (CO)                        | (CO)
                        2. DIRECTIONAL CLEANOUT       3. INTERVAL CLEANOUT

Summary of Mandatory Locations:

1. Base of Every Vertical Stack: A cleanout must be provided at the base of each vertical waste or soil stack before it turns horizontal into the building drain.
2. Maximum Horizontal Intervals (100 Feet): Cleanouts must be installed at intervals of not more than 100 feet on horizontal building drains and building sewers.
3. Changes of Direction Greater than 45°: A cleanout is required for each aggregate horizontal change in direction exceeding 45 degrees (e.g., a 90 degree turn made by a single quarter bend or two 45 degree fittings).
   • Exception (IPC 708.1.4): A cleanout is not required for an aggregate change of direction up to 135 degrees if an upstream cleanout is located within 40 feet of developed length.
4. Building Drain / Building Sewer Junction: Near the junction of the building drain and building sewer, either just inside the foundation wall or outside within 10 feet of the wall.
5. Manholes on Large Piping: On commercial building sewers 8 inches and larger, manholes are required at every change of direction, grade, elevation, or size, and at intervals not exceeding 300 to 400 feet.

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3. Working Clearances Around Cleanouts

A cleanout is worthless if a service plumber cannot insert a rigid steel cable machine in front of it. Clearances are strictly enforced by inspection authorities.

  IPC 708.1.9 (2018 IPC)                 UPC 707.9 (2018 UPC)
  +--------------------------+           +--------------------------+
  |  Pipe 6" and SMALLER     |           |  Pipe 2" and SMALLER     |
  |  [CLEANOUT] <--- 18" --->|           |  [CLEANOUT] <--- 12" --->|
  |                          |           |                          |
  |  Pipe 8" and LARGER      |           |  Pipe EXCEEDING 2"       |
  |  [CLEANOUT] <--- 36" --->|           |  [CLEANOUT] <--- 18" --->|
  +--------------------------+           +--------------------------+

Clearance Rules — the two adopted codes set different numbers, so read the question:

• IPC Section 708.1.9: cleanouts on 6-inch and smaller piping require a clearance of not less than 18 inches (457 mm) from, and perpendicular to, the face of the opening; cleanouts on 8-inch and larger piping require not less than 36 inches (914 mm) for rodding.
• UPC Section 707.9 (2018 edition): cleanouts in piping 2 inches or less require not less than 12 inches (305 mm) of clearance in front of the cleanout; cleanouts in piping exceeding 2 inches require not less than 18 inches (457 mm). The 2021 UPC raises these to 18 in by 18 in and 24 in by 24 in, which would apply in Texas only if the Board adopts the 2021 editions.
• Under-Floor / Crawl Space Cleanouts: Where cleanouts are located under floors or in crawl spaces, the access opening through the foundation/floor must be at least 20 inches × 30 inches, and the cleanout must be located within 20 feet of the access opening (or extended up through the floor / to an outside wall).

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4. Cleanout Plugs, Traffic Covers, & Direction of Flow

Plug Types and Traffic Areas

• Plug Materials: Cleanout plugs must be made of heavy brass or approved virgin plastic (PVC or ABS) conforming to plumbing standards.
• Raised Nut vs. Countersunk Socket:
  • In unfinished basements, crawl spaces, and exposed wall pipe chases, plugs may have a standard raised square nut for wrench grip.
  • In finished floors, foot traffic walkways, vehicular driveways, and equipment paths, cleanouts must be equipped with countersunk flush plugs or heavy-duty floor cleanout assemblies with threaded scoriated cover plates. Raised plugs in these areas constitute a prohibited tripping hazard and are susceptible to vehicle breakage.

Direction of Flow & Two-Way Cleanouts

• Flow Orientation: Cleanout fittings must be installed so that the cleanout opens in the direction of flow of the drainage line or perpendicular to it (such as a tee cleanout in a vertical stack). Cleanouts must never be angled upstream against the flow.
• Two-Way Cleanouts: A "two-way" or "double" cleanout fitting is frequently installed outside the foundation on the building sewer. This fitting permits a rodding snake to be run either back upstream toward the house or downstream toward the street main.