Trade Exam · Module 2
Plumbing Math
Nail slope calculations (1/4 inch per foot for 3-inch and smaller), pressure loss (0.433 psi per foot of elevation), 45-degree offset travel (offset × 1.414), and drainage fixture unit addition. These are your core plumbing math skills on the job and the exam.
Key Takeaways
- 2-1/2-inch and smaller drain pipes require 1/4 inch per foot slope; 3-inch and larger require 1/8 inch per foot slope.
Why This Matters on the Exam
Look, you're gonna get hammered with plumbing math questions. They're spread across the test, but they really pile on during the Planning and Estimating section (22% of your score). And here's the good news—the exam hands you a calculator. But you gotta know which formula to pull out and when to use it. These aren't advanced calculus problems; they're the bread-and-butter calculations you've probably done a hundred times on the job without thinking.
What You Must Know
You need to be able to calculate slope and total drop on a pipe run, figure out pressure loss from elevation, calculate 45-degree offset travel, add up drainage fixture units, do basic area calculations for storm drainage, and work with percentages for estimating. If you've been doing rough plumbing, you've done most of this already. The exam just wants to make sure you can explain it and nail the numbers.
Keep reading — unlock the full lesson
You’re reading a free preview. Get the complete lesson plus everything you need to pass the California C-36 exam:
- All 63 in-depth lessons
- 1,200+ practice questions
- AI tutor (100 messages included)
- 18+ hours of audio lessons
- Full-length practice exams
- Pass guarantee