How to Pass the Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) Exam
You don't have to guess how to prepare for the Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) exam. This guide lays it out: the key facts from the official bulletin, the topics on the test, the books you need, sample questions with answers, and a study plan you can follow. Pearson VUE gives the exam.
Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) Exam Basics
Here's what the official bulletin says about the exam:
| Questions | 70 questions |
| Time limit | 3 hours |
| Passing score | a minimum score of 70 |
| Books in the exam room | Open book |
| Exam fee | $115 |
On exam day
- Questions are four-option multiple choice with one correct answer.
References you may bring
- International Residential Code® (2015)
Scheduling, changes and retakes
- Exams are scheduled through PearsonVUE at www.pearsonvue.com/ICC.
- Results for electronically administered examinations are available immediately after the exam is completed.
- You must wait 10 days before retaking a failed exam.
- Upon passing, contact the jurisdiction for any other requirements needed to become licensed.
Source: Denver, Colorado Contractor/Trades Examination Information Bulletin, Published June 3, 2026 (page headers read "August 19, 2025"). Check the bulletin before test day: fees and rules can change.
What's on the Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) Exam
The official content outline splits the exam into 6 topics:
| Topic | Questions | Share of the exam |
|---|---|---|
| General Requirements | 22 | 32% |
| Appliances and Equipment | 4 | 6% |
| Duct Systems | 11 | 15% |
| Combustion Air | 16 | 23% |
| Chimneys and Vents | 7 | 10% |
| Fuel Supply Systems | 10 | 14% |
Your Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) Study Plan
Your books are your best friend on this exam. It's open book, so the references on the bulletin's list are what you'll use on test day. Get your own copies in the editions the bulletin names.
Get to know them early. Spend time with each book's table of contents and index until you can find any major subject quickly. On an open-book exam, finding answers fast is the skill that counts.
Make the books yours. Highlight the sections you keep coming back to. Check the bulletin's rules on tabs and markings before you add any.
Put your energy where the points are. General Requirements and Combustion Air make up 55% of the exam, so start there.
Practice with the clock running. Our timed practice exams help you build the pace the real exam needs: about 2 minutes 34 seconds per question. Every attempt is another rep.
Keep going until you pass practice exams consistently. One good score is a great start. A few passing scores in a row is how you know you're ready.
Books You'll Need for the Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) Exam
The only listed reference is the 2015 International Residential Code.
Where to get them:
Test Day Tips
Start with a quick pass through the whole exam. Answer every question you're sure about and bookmark the rest. Every exam lets you return to bookmarked questions, so nothing is lost by moving on. One catch: some exams lock the questions you've already seen once you take a break, so clear your bookmarks before any break.
Then come back to your bookmarks and work through them one at a time. Keep an eye on the clock: you have 3 hours for 70 questions, which is about 2 minutes 34 seconds per question. Before you finish, make sure every question has an answer. A blank can't earn a point.
Study Tips
Take this practice exam several times. The goal is to consistently clear your exam's passing score — often around 70–75% — so passing feels routine before you walk into the real test.
Don't let the clock rattle you. It's easy to feel overwhelmed when facing a page full of questions, a racing mind, and a ticking clock. Stay calm and stick to your planned pace. If you've been monitoring your progress consistently, you'll have enough time to finish. Even if the final minutes feel rushed, as long as you have only as many questions remaining as you should at that point, you're exactly where you need to be.
Your license won't show your exam score. Whether you ace it or squeak by, you walk out licensed either way — as we like to say, C's get licenses. Aim to pass, not to be perfect, and don't tally your score as you go; that pressure only drags your performance down.
You're given plenty of time, so use as much of it as you need. Don't get rattled when other people finish early — finishing first isn't a prize. Work at your own steady pace and review your answers before you submit.
After each practice test, note the topics you miss most and spend your next session there. Re-testing weak areas yields far more score gain than re-reading what you already know.
Try These Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) Practice Questions
Give these a try. They come from our practice question bank, each with its answer and reference.
Sample 1 — Fuel Supply Systems
Question: You are sizing combustion air openings and the manufacturer's free-area data for the metal grilles being used is unavailable. What free area must be assumed for metal louvers and grilles?
- A. 90 percent
- B. 50 percent
- C. 75 percent
- D. 25 percent
Correct Answer: C
IRC 2015 Section G2407.10 states that where the design and free area of louvers and grilles are not known, wood louvers shall be assumed to have 25-percent free area and metal louvers and grilles 75-percent free area.
Reference: IRC 2015 Section G2407.10
Sample 2 — Chimneys and Vents
Question: The code provisions governing the reduction of required clearances for chimneys, vents, appliances and equipment specifically identify which of the following as a combustible material?
- A. Plaster on metal lath
- B. Mineral wool batts
- C. Gypsum board
- D. 24-gage sheet metal
Correct Answer: C
IRC 2015 Section G2409.1 (308.1) states that the section governs the reduction in required clearances to combustible materials, 'including gypsum board,' and combustible assemblies for chimneys, vents, appliances, devices and equipment.
Reference: IRC 2015 Section G2409.1 (308.1)
Sample 3 — Appliances and Equipment
Question: A freestanding range is being installed in a kitchen with an unprotected combustible cabinet above. What is the minimum required vertical clearance from the cooking top to the unprotected combustible material?
- A. 36 inches
- B. 18 inches
- C. 30 inches
- D. 24 inches
Correct Answer: C
IRC 2015, Section M1901.1 requires freestanding or built-in ranges to have a vertical clearance above the cooking top of not less than 30 inches (762 mm) to unprotected combustible material; reduced clearances are permitted in accordance with the listing and labeling of range hoods or appliances.
Reference: IRC 2015 Section M1901.1
Sample 4 — General Requirements
Question: When preparing pipe ends for a ground-source heat-pump ground-loop system, pipe must be cut square, reamed and free of burrs. Which materials are also required to be chamfered?
- A. CPVC, PE and PVC pipe
- B. Copper and brass tubing
- C. Steel and stainless steel pipe
- D. PEX and PE-RT tubing
Correct Answer: A
IRC 2015 Section M2105.7 requires that CPVC, PE and PVC pipe be chamfered, with pipe ends having full-bore openings and not undercut.
Reference: IRC 2015 Section M2105.7
Why Practice Online?
Reading questions in a PDF is a start, but it doesn't prepare you for the clock. Our practice exams are timed and on a screen, so you build speed along with knowledge. Each attempt draws a new set of questions from our bank, and your results show your score by topic so you know where to focus next.
Ready to Start?
Take the free Denver Residential Mechanical (Class C) (ICC F32, 2015 IRC) practice exam and see where you stand today. Then focus on the topics that need the most work. For the official rules, read the exam bulletin, and see the licensing board's website.