Spot the Violation

PlumbingDrainage piping & fittingsLevel 32018 UPC

Underground rough-in around a column pad

Looking down at a new basement before the slab is poured. A 3 in. white PVC building drain lies in compacted sand. It starts at a capped cleanout riser at the lower right, runs left along the near side past a wye to a capped toilet riser, turns 90 degrees through a pair of 45-degree bends to run up the left side past a 2 in. shower riser, turns another 90 degrees through a second pair of 45-degree bends, and runs right along the far side, around a square concrete column pad, to pass through the foundation wall at the upper right. A shovel and cans of primer and cement lie on the sand. 3 IN PVC DWV SCH 40 ASTM D2665 3 IN PVC DWV SCH 40
Basement underground rough-in, before the slab pour

What's wrong here?

  1. The drain turns a total of 180 degrees with no cleanout beyond the upper-terminal cleanout
  2. Two 1/8 bends may not be paired to make a 90-degree turn in a building drain
  3. Cleanouts are not required on piping below the basement floor
  4. The upper-terminal cleanout must be a two-way cleanout outside the building
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Show the answer and the code reference

The answer

The building drain turns twice, 90 degrees each time through a pair of 1/8 bends, for 180 degrees in total, and the only cleanout is at the upper terminal. UPC 707.4 requires an additional cleanout for each aggregate horizontal change of direction exceeding 135 degrees.

Correct choice: 1. The drain turns a total of 180 degrees with no cleanout beyond the upper-terminal cleanout

UPC 707.4 requires a cleanout at the upper terminal of each horizontal drainage pipe, one for each 100 ft of developed length, and an additional cleanout in a drainage line for each aggregate horizontal change in direction exceeding 135 degrees. A cable fed in at the upper-terminal cleanout here has to go through four 1/8 bends, 180 degrees in all, before it reaches the far run and the sewer, and it binds in the second turn. The upper-terminal cleanout is present and the bends themselves are proper fittings; what is missing is the extra access point once the turns add up past 135 degrees. Underground cleanouts also have to be brought up to the finished floor so they can be reached after the pour.

How to fix it

Before the slab is poured, add a cleanout on the left run between the two turns, for example a wye set so a cable fed into its branch heads downstream, with the branch brought up to finished-floor level and capped. Then neither stretch between cleanouts turns more than 135 degrees. Or reroute so the total horizontal change of direction is 135 degrees or less. Re-test after the change.

Code references

  • UPC 2018 707.4 — Location

    Each horizontal drainage pipe is to have a cleanout at its upper terminal and one for each 100 ft of developed length, and an additional cleanout is to be provided in a drainage line for each aggregate horizontal change in direction exceeding 135 degrees. Exceptions cover short lines, steep-sloped lines, most piping above the lowest floor, and a two-way cleanout substituting for the upper-terminal cleanout.

    Drills citing 707.4

  • UPC 2018 706.1 — Approved Fittings

    Changes in direction of drainage piping are to be made with approved fittings at the angles of a 1/16, 1/8 or 1/6 bend, or other approved fittings of equivalent sweep.

    Drills citing 706.1

Minnesota

MN status unverifiedConfidence: low

Minnesota adopts the 2018 Uniform Plumbing Code with Minnesota amendments as the Minnesota Plumbing Code (Minn. Rules ch. 4714, effective Dec. 17, 2021). Search-result excerpts indicate Minnesota amends UPC 707.4 (apparently in part 4714.0707), reportedly in the exceptions (keeping cleanouts for kitchen sinks and urinals above the lowest floor) and with a cleanout for each urinal, while keeping the upper-terminal, 100 ft and 135-degree requirements. The amended text could not be read; check ch. 4714 before relying on it.

About the Minnesota Plumbing Code

Citation under review. Minnesota status is unverified: confirm what Minn. Rules ch. 4714 (apparently part 4714.0707) changes in UPC 707.4, and that the 135-degree aggregate sentence survives the amendment. The 135-degree sentence and exceptions 3 and 4 are in the model 2018 UPC 707.4 as the verifier knows the text, but this was not checked against the code book.

Why the other choices are wrong

  • Two 1/8 bends may not be paired to make a 90-degree turn in a building drain. UPC 706.1 lists the 1/8 bend for changes of direction in drainage piping, and two of them back to back is the textbook way to turn a horizontal drain 90 degrees.
  • Cleanouts are not required on piping below the basement floor. It is the reverse. 707.4 exception 3 drops cleanouts only above the lowest floor, and even there it keeps them for the building drain and its horizontal branches. An underground building drain gets the full cleanout rules.
  • The upper-terminal cleanout must be a two-way cleanout outside the building. 707.4 exception 4 lets a two-way cleanout at the building drain/sewer connection substitute for the upper-terminal cleanout, but it is optional. A cleanout riser at the upper end, brought up to the floor, satisfies the rule.
Code complianceLevel 3 · Master#cleanout#change of direction#building drain#underground#rough-in

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