FreeConstruction · Plumbing

Pipe slope and drain fall

Total fall, end elevation and percent grade for a drain line, checked against the plumbing code minimum.

Free for the plumber role. No account needed.

Your numbers

Run length (ft)Horizontal length of the drain.Slope1/4 in per ft is the default for small drains.Pipe diameterCode minimum slope depends on size.Starting invert depth (in)Depth below finished floor or grade at the upper end.

For the grade sheet6 more, filled with typical values

Ground falls along the run (ft)How much lower the ground is at the lower end than at the upper end. Negative if it rises.Bedding under the pipe (in)Sand or stone under the pipe, from the spec or the pipe maker's instructions.Trench width (in)Bucket width, or the width the trench box needs.Cleanout spacing (ft)The most your adopted plumbing code allows between cleanouts on this line.Pipe price ($ per ft)Installed-material price per foot of this pipe size.Dig and backfill ($ per CY)Excavation, bedding and backfill per cubic yard of trench.

Pipe slope and drain fallForge by Norventus

How it works

Press Calculate to see the fall, the depth at the lower end and the code check.

The drain line, tilted to its slopeHangers, slab and stackWater in the cut-awayThe drawing follows your numbers as you type. Press Calculate and the fall, the depth at the lower end and the code check appear here, worked out by the tool. The drawn tilt is exaggerated.

Result

Ready when you are.Enter your numbers and press Calculate.

References

Check the work against these

A grade sheet with invert and trench depths at five stations, the OSHA trench check, dig volumes, cleanouts, cost and the run at each slope, with sources. Numbers in the result and in the plain-words read point here.

1
International Plumbing Code 2021, Chapter 7 Sanitary DrainageCode
International Code Council
Section 704.1 and Table 704.1: 1/4 in per ft for pipe 2-1/2 in and smaller, 1/8 in per ft for 3 to 6 in, 1/16 in per ft for 8 in and larger; Section 708 sets where cleanouts go. Your adopted code (IPC or UPC) and the inspector govern.
2
OSHA Fact Sheet: Trenching and Excavation SafetyHandout
OSHA, as posted by Montana State University LTAP
A protective system (sloping, shoring or a trench box) for trenches 5 ft deep or more; a ladder, stairway or ramp within 25 ft of lateral travel at 4 ft or more; spoil kept at least 2 ft back from the edge.
3
OSHA standard interpretation (17 March 2009): means of egress from trenchesCode
U.S. Occupational Safety and Health Administration
Quotes 29 CFR 1926.651(c)(2): a stairway, ladder, ramp or other safe way out in trenches 4 ft or more deep, available at all times.

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Pipe slope and drain fall

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