Drainage
Drainage Pipe Sizing Reference
Complete reference for drainage pipe sizing using IPC Table 710.1 and UPC Table 703.2, including slope requirements and maximum length limitations.
Introduction
Drainage pipe sizing uses Drainage Fixture Units (DFU) and code-specific tables that specify maximum unit loading and maximum pipe length for each pipe diameter. This reference covers both IPC and UPC sizing tables and slope requirements.
IPC Table 710.1 - Maximum Unit Loading
IPC drainage pipe sizing (horizontal and vertical):
| Pipe Size | Max DFU (Vertical) | Max DFU (Horizontal) | Max Length (ft) |
|-----------|--------------------|-----------------------|-----------------|
| 1-1/4" | 1 | 1 | 45 |
| 1-1/2" | 2 | 1 | 65 |
| 2" | 6 | 3 | 85 |
| 3" | 24 | 20 | 212 |
| 4" | 70 | 36 | 300 |
| 5" | 180 | 110 | 390 |
| 6" | 384 | 240 | 510 |
| 8" | 960 | 640 | 750 |
Slope: 1/4" per foot for pipes <3", 1/8" per foot for pipes >=3".
UPC Table 703.2 - Maximum Unit Loading
UPC drainage pipe sizing:
| Pipe Size | Max DFU (Vertical) | Max DFU (Horizontal) | Max Length (ft) |
|-----------|--------------------|-----------------------|-----------------|
| 1-1/4" | 1 | 1 | 45 |
| 1-1/2" | 2 | 1 | 65 |
| 2" | 16 | 8 | 85 |
| 3" | 48 | 35 | 212 |
| 4" | 256 | 216 | 300 |
| 5" | 600 | 428 | 390 |
| 6" | 1380 | 720 | 510 |
| 8" | 3600 | 2640 | 750 |
Note: UPC values differ from IPC. For 1/8" per foot slope, multiply horizontal DFU by 0.8.
Slope Requirements
Both IPC and UPC specify minimum slopes for horizontal drainage piping:
- **Pipes <3"**: 1/4" per foot (2.1% slope)
- **Pipes >=3"**: 1/8" per foot (1.0% slope)
These slopes ensure self-cleaning velocity (minimum 2 ft/s) to prevent solids deposition. Plumbing Booster checks slope compliance automatically.
How Plumbing Booster Automates It
The Drainage System module automatically selects the correct sizing table based on the chosen plumbing code. DFU values are auto-calculated from fixtures, and the software sizes all branches, stacks, and building drains. Slope compliance is verified, and the Drainage Riser Diagram shows pipe sizes visually.
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