6.1 Cleanout Locations, Sizing, Clearances & Accessibility

6.1 Cleanout Locations, Sizing, Clearances & Accessibility

Quick Answer: Under IPC Section 708, cleanouts are mandated at the junction of the building drain and building sewer (inside or outside the wall, brought up to finished ground or basement floor level), at every change of direction greater than 45 degrees, at the base of every waste or soil stack, and at intervals of not more than 100 feet along horizontal drains and building sewers. The 2006 IPC has no cleanout sizing table: Section 708.7 requires the cleanout to be the same nominal size as the pipe up to 4 inches, with a 4-inch minimum for larger pipe, subject to three narrow exceptions. Rodding clearance under Section 708.8 is 18 inches for pipes 6 inches and smaller and 36 inches for pipes 8 inches and larger. In floors and traffic paths, countersunk square plugs are required so a raised head is not a trip hazard. And the Indiana change to remember: 675 IAC 16-1.4-8(f) deletes the stack-within-10-feet exception from Section 708.3.5.

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Regulatory Framework & Purpose of Cleanouts (IPC Section 708)

The sanitary drainage system relies on gravity flow, suspended solids transport, and pneumatic balance to convey liquid waste away from plumbing fixtures. Over time, grease accumulation, mineral scale, foreign objects, hair, and root intrusion inevitably cause partial restrictions or complete blockages. Without accessible, code-compliant cleanouts, clearing stoppages would require cutting structural piping, dismantling architectural finishes, or pulling heavy fixtures off their mounts.

The International Plumbing Code (IPC) Chapter 7, Section 708, establishes comprehensive requirements governing where cleanouts must be located, how they must be sized, how much spatial clearance must be preserved around them, and what physical materials may be employed. In Indiana, these standards are enforced under 675 IAC 16-1.4, ensuring that all residential, commercial, and industrial drainage systems maintain lifelong maintainability without threatening the sanitary integrity of the building.

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Mandatory Cleanout Locations (IPC 708.3)

Section 708.3 says cleanouts shall be located in accordance with Sections 708.3.1 through 708.3.6. Learn the subsection numbers, not just the concepts — open-book items routinely ask which subsection applies.

+-------------------------------------------------------------------------+
|              THE SIX SUBSECTIONS OF IPC SECTION 708.3                   |
+-------------------------------------------------------------------------+
| 708.3.1 Horizontal drains within buildings | Not more than 100 ft apart |
| 708.3.2 Building sewers                    | Not more than 100 ft apart |
| 708.3.3 Changes of direction               | Each change > 45 degrees   |
| 708.3.4 Base of stack                      | Each waste or soil stack   |
| 708.3.5 Building drain / sewer junction    | Near the junction          |
| 708.3.6 Manholes                           | Gas-tight secured covers   |
+-------------------------------------------------------------------------+

1. Junction of Building Drain and Building Sewer (708.3.5) — and a key Indiana amendment

A cleanout must be provided near the junction of the building drain and the building sewer. This is the primary gateway for clearing a lateral stoppage before waste backs up into the building.

• Location Allowance: the code says the cleanout shall be either inside or outside the building wall and shall be brought up to the finished ground level or to the basement floor level. The 2006 IPC does not impose a "within 2 feet of the wall" dimension — that figure comes from other codes and from local ordinances.
• Two-way cleanouts: an approved two-way cleanout is allowed at this location to serve as the required cleanout for both the building drain and the building sewer.
• The Indiana amendment: the model text ends with an exception — the junction cleanout is not required where a cleanout on a 3-inch or larger soil stack sits within 10 feet developed length of the building drain / building sewer connection. 675 IAC 16-1.4-8(f) deletes the fourth sentence of Section 708.3.5 without substitution. In Indiana that exception is gone: the junction cleanout is always required, no matter how close the stack cleanout is. This is one of the cleanest Indiana-versus-model-code distinctions on the whole exam.
• Outside Cleanouts: where installed outside, bring the riser to finished grade in an approved box or vault so it survives mowers, soil compaction and traffic.

2. Changes of Direction Greater than 45 Degrees (708.3.3)

Horizontal drainage lines deposit debris at bends because velocity drops and flow becomes turbulent. Section 708.3.3 reads: "Cleanouts shall be installed at each change of direction greater than 45 degrees (0.79 rad) in the building sewer, building drain and horizontal waste or soil lines. Where more than one change of direction occurs in a run of piping, only one cleanout shall be required for each 40 feet (12 192 mm) of developed length of the drainage piping."

• Read the relief clause carefully. It is not an exception tied to a single upstream cleanout; it is a density cap. A run with four 90-degree bends inside 40 feet of developed length needs one cleanout for that 40-foot stretch, not four.
• Fitting combinations: a 90-degree change made with two 45-degree fittings is still a change of direction greater than 45 degrees.

3. Base of Every Vertical Soil and Waste Stack (708.3.4)

Section 708.3.4 is one sentence: "A cleanout shall be provided at the base of each waste or soil stack."

• The cleanout must be installed at the base of the stack or immediately adjacent to the stack base where the vertical drop transitions into the horizontal building drain or branch through a wye and 1/8 bend or long-sweep fitting.
• For stacks extending through multiple stories, this base cleanout provides vertical access for high-pressure hydro-jetting nozzles and heavy-duty mechanical sectional cables.

4. Horizontal Run Intervals — the 100-Foot Rule (708.3.1 and 708.3.2)

Two separate subsections carry the same 100-foot number, and the exam likes to see whether you know which is which:

• 708.3.1 Horizontal drains within buildings: "All horizontal drains shall be provided with cleanouts located not more than 100 feet (30 480 mm) apart."
• 708.3.2 Building sewers: cleanouts not more than 100 feet apart measured from the upstream entrance of the cleanout. For building sewers 8 inches (203 mm) and larger, manholes must be provided instead, located not more than 200 feet (60 960 mm) from the junction of the building drain and building sewer, at each change in direction, and at intervals of not more than 400 feet (122 m) apart.
• 708.3.6 Manholes: manholes serving a building drain shall have secured gas-tight covers and shall be located in accordance with 708.3.2.

If a horizontal building drain runs 230 feet, at least two intermediate cleanouts are needed so that no segment between cleanouts exceeds 100 feet.

5. What the 2006 IPC Does Not Require

Other model codes (notably the UPC) mandate a cleanout on every horizontal branch serving sinks and urinals. The 2006 IPC does not, and Indiana did not add one. Section 708.3 lists exactly six triggers, and a sink or urinal branch is not among them.

That said, sink and urinal branches genuinely do foul: sink waste deposits fats, oils and grease along the pipe crown, and urinal waste precipitates hard calcium phosphate scale. Indiana does require a cleanout immediately downstream of every interceptor or separator (amended Section 1003.1), which is where most commercial kitchen branches get their access. Install cleanouts on these branches as good practice — just do not cite Section 708.3 for it on the exam.

6. Two More Rules Worth Tabbing

• 708.5 Opening Direction: every cleanout shall be installed to open in the direction of the flow of the drainage pipe or at right angles to it.
• 708.6 Prohibited Installation: cleanout openings shall not be used for the installation of new fixtures, except where approved and where another cleanout of equal access and capacity is provided.
• 708.9 Access: access shall be provided to all cleanouts.

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Cleanout Sizing (IPC Section 708.7) — There Is No Table

A frequent study-guide error is to invent a "Table 708.2" of reduced cleanout sizes. The 2006 IPC has no cleanout sizing table. Section 708.2 is Cleanout Plugs (a materials section), and sizing lives in Section 708.7 Minimum Size, which is a two-sentence rule:

"Cleanouts shall be the same nominal size as the pipe they serve up to 4 inches (102 mm). For pipes larger than 4 inches nominal size, the minimum size of the cleanout shall be 4 inches (102 mm)."

Exceptions to 708.7:

1. "P" trap connections with slip joints or ground joint connections.
2. Stack cleanouts that are not more than one pipe diameter smaller than the drain served.
3. Cast-iron cleanout sizing follows the referenced standards in Table 702.4 — ASTM A 74 for hub and spigot fittings, or ASTM A 888 / CISPI 301 for hubless fittings.

Exam Trap Alert: the UPC does permit reduced cleanouts — a 2-inch pipe taking a 1-1/2-inch cleanout, a 3-inch pipe taking a 2-1/2-inch cleanout. The IPC does not. Under 708.7 the only size reductions are the three exceptions above, the most useful of which is the stack cleanout exception: a stack cleanout may be one pipe diameter smaller than the drain served, so a 4-inch stack may take a 3-inch cleanout.

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Clearances for Rodding (IPC 708.8)

Installing a cleanout is meaningless if a plumber cannot get a rodding machine, a stiff spring-steel cable, or a jetter hose into it. Section 708.8 is short and the break point is 6 inches / 8 inches, not 2 inches / 3 inches:

"Cleanouts on 6-inch (153 mm) and smaller pipes shall be provided with a clearance of not less than 18 inches (457 mm) for rodding. Cleanouts on 8-inch (203 mm) and larger pipes shall be provided with a clearance of not less than 36 inches (914 mm) for rodding."

+-------------------------------------------------------------------------+
|                   MANDATORY RODDING CLEARANCES (708.8)                  |
+-------------------------------------------------------------------------+
|  Cleanouts on pipes 6 inches and smaller  |  18 inches minimum         |
|  Cleanouts on pipes 8 inches and larger   |  36 inches minimum         |
+-------------------------------------------------------------------------+

Clearance Applications

• 6 inches and smaller: an unobstructed working space of not less than 18 inches (457 mm). That single figure covers everything from a 1-1/4-inch fixture branch to a 6-inch building drain, which is why a 4-inch building drain cleanout needs 18 inches, not 24.
• 8 inches and larger: not less than 36 inches (914 mm), which is what a heavy floor-standing drum machine and a rigid cutting head actually need.
• 708.4 Concealed piping: cleanouts on concealed piping, on piping under a floor slab, in a crawl space less than 24 inches (610 mm) in height, or in a plenum must be extended through and terminate flush with the finished wall, floor or ground surface, or be extended to the outside of the building. Cleanout plugs shall not be covered with cement, plaster or any other permanent finish material. Where a cleanout must be concealed or terminated in an area subject to vehicular traffic, the covering plate, access door or cleanout must be of an approved type designed and installed for that purpose.

Concealed Piping and Access Covers

Cleanouts concealed behind finished walls or ceilings must be extended through the wall/ceiling using an extension pipe and flush wall plate, or must be accessible through an approved hinged access door or removable panel. The access opening must be large enough to allow removal of the cleanout plug and full operation of drain-cleaning tools without damaging the surrounding architectural finishes.

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Cleanout Plug Materials, Threads & Traffic Installations

Cleanout closures must maintain an airtight, gas-tight, and water-tight seal against system pressures, sewer gas migration, and groundwater infiltration.

      RAISED HEAD PLUG                        COUNTERSUNK PLUG
     (Walls / Unfinished Areas)             (Floors / Traffic Areas)
          +--------+                               +----------------+
          | SQUARE |                               | [SQUARE RECESS]|   <-- Flush
     +----+  HEAD  +----+                          +----------------+       Surface
     |    +--------+    |                          |  |          |  |
     |   MALE THREADS   |                          |   MALE THREADS |   <-- Flush with
     +------------------+                          +----------------+       floor collar

Approved Plug Materials

Cleanout plugs must be constructed of brass or approved plastic (polyvinyl chloride - PVC, or acrylonitrile-butadiene-styrene - ABS). Brass plugs must comply with ASTM standards and feature tapered American Standard Pipe Threads (NPT). Plastic plugs must match the solvent-weld piping material of the drainage assembly. Plugs made of wood, cork, rubber expansion knockouts, or makeshift lead caps are strictly prohibited on permanent drainage systems.

Raised Head vs. Countersunk Plugs

Plugs are manufactured in two basic configurations:

1. Raised Square Head: Features an elevated square nut or lug protruding 1/2 to 3/4 inch above the face of the plug, allowing easy tightening with a large adjustable wrench or pipe wrench. Raised head plugs are permitted only in unfinished utility rooms, open basements, crawl spaces, or inside wall access boxes where pedestrian or vehicular traffic cannot contact them.
2. Countersunk Square Slot: Features a recessed square socket flush with the plug rim, operated using a square-shank cleanout tool or specialized ratchet key. Countersunk plugs are strictly mandatory in floors, paved walkways, hallways, driveways, ramps, and general traffic areas. A raised head installed in a walking surface constitutes an immediate tripping hazard and safety violation under building codes and OSHA standards.

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Direction of Flow, Fitting Combinations & Two-Way Cleanouts

A cleanout must be oriented so that drain-cleaning tools enter the piping in the direction of drainage flow or perpendicular to the pipe run. A cable pushed against the direction of flow will snag on fitting shoulders, damage internal pipe walls, or punch through thin-wall transitions.

             DIRECTIONAL CLEANOUT (Wye & 1/8 Bend Combination)

     Cleanout Riser Plug
             |
             v
            [ ]
             \   <-- 45-degree slope guides snake downstream
              \ 
  =============+===============> DRAINAGE FLOW DIRECTION
   Horizontal Branch

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                   TWO-WAY CLEANOUT ASSEMBLY

            Upstream Riser      Downstream Riser
                 [ ]                 [ ]
                  \                   /
                   \                 /
  <--- RODDING      +---------------+==============> RODDING
      UPSTREAM                      DRAINAGE FLOW    DOWNSTREAM

Fitting Combinations

• Wye and 1/8 Bend: The most common and effective cleanout configuration is an oblique 45-degree wye fitting paired with a 45-degree (1/8 bend) street elbow. This combination creates a smooth, continuous 45-degree sweep that guides the rotating snake directly downstream into the horizontal run without binding.
• Sanitary Tees: A sanitary tee may be used as a cleanout fitting only on vertical piping where the branch of the tee accepts the cleanout plug and points downward in the direction of flow. Sanitary tees are prohibited on horizontal piping runs where the branch opening is positioned horizontally, as cables can easily become jammed against the internal 90-degree baffle.
• Two-Way Cleanouts: Where access is required in both upstream and downstream directions (such as at the building drain foundation exit), a two-way directional cleanout fitting or a pair of opposed wye-and-1/8-bend fittings may be installed. A two-way cleanout allows rodding backward into the building's internal collection grid and forward into the municipal street sewer from a single outdoor station.

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Prohibited Cleanout Practices

Plumbing inspectors and code officials will fail installations that violate the integrity and accessibility of cleanout assemblies. The following practices are expressly prohibited:

1. Use as Fixture Drains: Cleanout openings cannot be repurposed or tapped to serve as a drain connection for a sink, washing machine, or relief valve. A cleanout must remain a dedicated maintenance access terminal.
2. Inaccessible Concealment: Encasing a cleanout plug inside a solid concrete slab, burying it beneath ceramic tile, or sealing it behind permanent wood or drywall paneling without an access cover is an immediate violation.
3. Under-Sized Cleanout Openings: Reducing a cleanout below the Section 708.7 minimum is a violation, even where space is tight. The only reductions the 2006 IPC allows are the three exceptions to 708.7 — a P-trap slip-joint or ground-joint connection, a stack cleanout not more than one pipe diameter smaller than the drain served, and cast-iron sizing under the Table 702.4 standards.
4. Counter-Flow Orientation: Installing a single wye fitting oriented against the direction of flow, which forces drain cables backward into fixture branches rather than downstream toward the sewer main.
5. Unapproved Plugs: Installing rubber test plugs, galvanized malleable iron pipe caps, or mechanical expansion plugs as permanent cleanout closures.

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Summary Reference Tables

Table 1: Cleanout Requirements Summary

Table 2: Cleanout Minimum Size (IPC 708.7)