What is the maximum spacing between cleanouts?

Under IPC 708, horizontal drainage piping 4 inches and smaller needs a cleanout at least every 100 feet, and piping larger than 4 inches at least every 150 feet. The distance is measured as developed length along the pipe, including the equivalent of fittings.

Where else are cleanouts required?

Besides the spacing rule, a cleanout is required at or near the base of each waste or soil stack, at each change of direction greater than 45 degrees, and where the building drain connects to the building sewer. This tool counts all of these.

Does a direction change always need a cleanout?

A change of direction greater than 45 degrees requires a cleanout so a snake can reach the bend, though a single cleanout can serve more than one nearby fitting if it provides access to all of them. Aggregated 45-degree offsets that together exceed 45 degrees are treated as a direction change.

What is the building drain cleanout?

It is the cleanout where the building drain meets the building sewer, often a two-way cleanout that lets a snake run both upstream into the house and downstream toward the main. It is one of the most important access points and is required on essentially every system.

Why do the rules differ between code editions?

The exact spacing distances and the over-4-inch threshold shift slightly between IPC cycles and local amendments. This tool uses the common 100 ft and 150 ft values, but always confirm against your adopted code edition before submitting for inspection.

What is the Drain Cleanout Spacing & Location Calculator?

Applies IPC Section 708 cleanout rules — 100 ft maximum spacing for pipe 4 in and smaller, 150 ft for larger, plus cleanouts at stack bases, direction changes over 45 degrees, and the building drain junction — to count the minimum cleanouts a drain route needs. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Drain Cleanout Spacing & Location Calculator

Name: Drain Cleanout Spacing & Location Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Cleanouts are the access points that let a drain be snaked when it clogs, and the IPC is specific about where they must go. This calculator applies IPC Section 708 to count the minimum cleanouts a drainage run needs and tells you exactly where each one belongs — useful for planning a new DWV system, verifying a design before inspection, or checking an existing installation.

How it works

Required cleanouts come from a spacing rule plus a set of fixed trigger locations:

max spacing   = 100 ft  if pipe ≤ 4 in nominal
              = 150 ft  if pipe > 4 in nominal

intermediate  = ceil(run length / max spacing) − 1

fixed needs   = 1 building-drain cleanout
              + 1 per waste or soil stack base
              + 1 per direction change > 45°

total         = fixed needs + intermediate

The developed length is measured along the pipe’s centreline, including the equivalent length of fittings on long runs. Any single continuous run longer than the spacing limit triggers one or more intermediate cleanouts.

Worked example

A 250 ft, 4-inch building drain with three direction changes greater than 45° and one waste stack:

Max spacing for ≤ 4 in pipe = 100 ft
Intermediate cleanouts = ceil(250 / 100) − 1 = 2
Building-drain junction = 1
Stack base = 1
Direction changes = 3
Total minimum = 7 cleanouts

Where each cleanout goes

Building-drain cleanout: At or near where the building drain leaves the structure to connect the building sewer. This is typically a two-way cleanout that allows a snake to run upstream into the building and downstream toward the main.

Stack-base cleanout: Installed within 2 feet of the base of each waste or soil stack, where the near-vertical stack transitions to the nearly horizontal building drain. This junction takes heavy impact from falling waste and is a common clog point.

Direction-change cleanout: Required at each change of horizontal direction greater than 45 degrees. A single cleanout may serve more than one fitting if it provides cable access through all of them — this matters in tight mechanical spaces where fitting two cleanout wyes would be impractical.

Intermediate cleanouts: Spaced along long, straight horizontal runs so that no section of drain is more than 100 ft (or 150 ft for large pipe) from an access point.

What this calculator does not cover

This tool applies the common IPC 708 spacing rules. Code editions vary; some local jurisdictions have amended the 100 ft / 150 ft limits or reduced the direction-change threshold. Vertical stacks do not have the same horizontal spacing requirements. Always verify against your adopted edition and local amendments before submitting for inspection.