Everything you need for the P1 Residential Plumbing Inspector exam — based on the 2024 International Residential Code® (IRC)
6-hour structured review covering Sanitary Drainage, Water Supply and Distribution, Vents, and more — weighted to match P1 exam percentages
Timed 60-question simulation matching the P1 exam format with detailed answer explanations
Digital flip-cards for key terms, code sections, and references from the 2024 International Residential Code® (IRC)
Listen-and-learn audio covering high-yield P1 topics for studying on the go
Color-coded tab system for the 2024 International Residential Code® (IRC) — find answers fast during your open-book exam
Insert sheets with key tables, formulas, and values from the 2024 International Residential Code® (IRC) for blank code book pages
6-8 week structured program prioritized by P1 category weights — heaviest topics first
Intensive pre-exam review focusing on the highest-weighted P1 topics: Sanitary Drainage, Water Supply and Distribution, Vents
Our study materials cover every category tested
Get a head start on your P1 Residential Plumbing Inspector exam preparation with this preview of our comprehensive study guide. Sign up for full access to all study materials.
Use this guide the day before or morning of your exam for focused, intensive review
This review is designed for your final prep session right before taking the P1 exam. It focuses on the highest-value topics and most commonly tested plumbing material.
Recommended Schedule:
Materials needed:
Sanitary drainage is 23% of your exam - nearly 1/4 of all questions. Master drainage sizing, slope, and cleanout requirements and you're well on your way to passing.
Tab these NOW if you haven't:
What are Fixture Units?
Common Fixture DFU Values - MEMORIZE THESE:
| Fixture | Trap Size | Drain Size | DFU |
|---|---|---|---|
| Water closet (tank) | 3" | 3" | 3 |
| Shower | 2" | 2" | 2 |
| Bathtub | 1-1/2" | 1-1/2" | 2 |
| Lavatory | 1-1/4" | 1-1/2" | 1 |
| Kitchen sink | 1-1/2" | 1-1/2" | 2 |
| Dishwasher | - | 1-1/2" | 2 |
| Washing machine | 2" | 2" | 2 |
| Floor drain | 2" | 2" | 1 |
Common Test Questions:
Exam Tip: Notice trap size vs drain size. Lavatory trap can be 1-1/4", but drain must be 1-1/2". Questions often test this distinction.
Building Drain: Below-grade horizontal drain collecting all drainage
Building Sewer: From building drain to public sewer or septic
Sizing based on:
Table P3005.4.1 Key Values:
3-inch pipe:
4-inch pipe:
Example Calculation:
"A building has 2 water closets (6 DFU), 2 lavatories (2 DFU), 2 showers (4 DFU), 1 kitchen sink (2 DFU), 1 washing machine (2 DFU). What size building drain at 1/4" slope?"
Total DFU: 6 + 2 + 4 + 2 + 2 = 16 DFU
Check Table P3005.4.1:
Common Test Questions:
Exam Tip: Always check BOTH pipe size AND slope. Same pipe at different slopes has different capacities.
Horizontal Branch: Drain pipe collecting multiple fixtures before connecting to stack or building drain
Table P3005.4.2 Key Values:
| Pipe Size | Max DFU |
|---|---|
| 1-1/2" | 3 |
| 2" | 6 |
| 3" | 20 |
| 4" | 160 |
Example:
"A horizontal branch serves one lavatory (1 DFU) and one shower (2 DFU). What minimum size?"
Total: 1 + 2 = 3 DFU
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Created by Levi Mittag — a Certified Building Official, Field Inspection Supervisor, and Lean Six Sigma Black Belt with 19 ICC certifications and 26 years in the building industry.
7 days free, then $12/mo. All 27 exams included. No credit card required.
Not just practice questions — a complete study system with audio, tabbing, and strategy.
Built by an active supervisor who uses these methods to train his own inspection team.