ICC B1 Residential Building Inspector Exam Guide: International Residential Code Study Plan
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The ICC B1 Residential Building Inspector exam from the International Code Council (ICC) has 60 open-book multiple-choice questions, a 2-hour limit and a passing scaled score of 75, all based on the International Residential Code (IRC). This guide covers cost, retakes, the content outline and the IRC Chapter 3 and 4 numbers you need for inspections of one- and two-family dwellings.
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ICC B1 Exam Facts at a Glance
| Item | ICC B1 |
|---|---|
| Questions | 60 multiple-choice |
| Time | 2 hours |
| Format | Open book (IRC) |
| Pass score | Scaled score of 75 (not a percentage) |
| Fee | $320 on ICC's exam shop. Purchases are final and valid for 365 days. |
| Retakes | 6 attempts in 6 months, paying each time |
| Scope | One- and two-family dwellings, townhouses up to 3 stories, accessory structures |
Sources: ICC B1 exam content outline, ICC B1 exam shop page, ICC before-the-exam page and ICC credentialing rules.
ICC B1 Content Outline
| Domain | Weight |
|---|---|
| Code Administration | 4% |
| Building Planning | 8% |
| Footings and Foundations | 16% |
| Floor Construction | 14% |
| Wall Construction and Coverings | 27% |
| Roof/Ceiling Construction | 14% |
| Public Safety and Special Construction | 17% |
Public safety covers egress, stairs, smoke detectors, flame spread and safety glazing. Our question bank covers IRC Chapters 3 to 8: building planning, public safety, foundations, floors, wall framing, wall coverings and roof framing.
IRC Egress and Escape Opening Numbers
| Item | IRC Requirement |
|---|---|
| Escape opening net clear area | 5.7 sq ft (5 sq ft at grade floor) |
| Minimum clear height / width | 24 in / 20 in |
| Sill height | 44 in maximum above the floor |
| Area well | 9 sq ft minimum, 36 in projection, ladder if deeper than 44 in |
| Egress door | Side-hinged, 32 in clear width, 78 in clear height |
| Exterior landing | 36 in deep. Up to 1-1/2 in below the threshold, or 7-3/4 in if the door doesn't swing over it. |
| Hallway | 3 ft minimum |
The figures are from 2021 IRC Chapter 3.
Stairs, Handrails and Guards
| Item | IRC Requirement |
|---|---|
| Stair width | 36 in |
| Headroom | 6 ft 8 in (6 ft 6 in on spiral stairs) |
| Riser / tread | 7-3/4 in maximum / 10 in minimum, each within 3/8 in variation |
| Nosing | 3/4 to 1-1/4 in |
| Handrail height | 34 to 38 in, with 1-1/2 in wall clearance and a 1-1/4 to 2 in round grip |
| Guards required | More than 30 in above the floor or grade below |
| Guard height | 36 in (34 in on stairs) |
| Guard openings | 4 in sphere (4-3/8 in on stairs, 6 in triangle) |
| Ramps | 1:12 at the egress door, 1:8 elsewhere. Handrail required steeper than 1:12. |
Building Planning: Rooms, Light, Garage and Fire Separation
- Habitable rooms need at least 70 sq ft, 7 ft in any horizontal dimension, and a 7 ft ceiling. Bathrooms and laundry rooms need 6 ft 8 in.
- Glazing must be at least 8 percent of the floor area, and the openable area at least 4 percent.
- Garage separation needs 1/2-inch gypsum board on the garage side, or 5/8-inch Type X under habitable rooms above.
- Doors from the garage must be 1-3/8-inch solid wood or steel, or 20-minute rated, and self-closing and self-latching.
- Two-family units need 1-hour separation (1/2-hour with sprinklers). Townhouse common walls need 2 hours, or 1 hour with sprinklers.
- Interior finishes are limited to a flame spread of 200 and a smoke-developed index of 450. Exposed insulation is limited to a flame spread of 25.
Smoke Alarms, CO Alarms and Safety Glazing
Smoke alarms go in each sleeping room, outside each sleeping area and on every story, including basements. Keep them at least 3 ft from a bathroom door and 20 ft from cooking appliances (ionization), 10 ft with a silencing switch, or 6 ft (photoelectric). CO alarms go outside each sleeping area, and inside a bedroom that has a fuel-burning appliance. Glazing is in a hazardous location within 60 in of the floor next to doors, or within 36 in of stair walking surfaces.
Footings and Foundations (IRC Chapter 4)
- Grade falls 6 in within the first 10 ft. Impervious surfaces slope 2 percent away.
- Exterior footings go at least 12 in below undisturbed ground and are protected from frost. Footing bottoms slope no more than 1:10.
- Anchor bolts are 1/2 in minimum, at 6 ft on center maximum, embedded 7 in, with two per plate and one within 12 in of each end.
- Foundation walls extend 6 in above grade (4 in with masonry veneer). Don't backfill until the wall is braced or anchored.
- Crawl spaces need 1 sq ft of vent per 150 sq ft, a vent within 3 ft of each corner, and access of 18×24 in through the floor or 16×24 in through a wall.
The figures are from 2021 IRC Chapter 4.
Who Should Take the ICC B1 Exam
The ICC B1 suits new residential inspectors, combination inspector trainees, builders and plans reviewers who work on one- and two-family dwellings. Its scope, per the ICC outline, is one- and two-family dwellings, townhouses up to three stories in height and their accessory structures. That makes it the building leg of residential inspection work. Many inspectors then add the residential electrical, plumbing and mechanical exams to build toward a combination credential, but check which mix your employer needs before you buy.
How to Use the IRC During the ICC B1 Exam
Because the B1 is open book, you win time by knowing where an answer lives, not by memorising every number. Use these habits:
- Start with the index. Look up the keyword ("guard", "anchor bolt", "crawl space") and go straight to the section.
- Tab the tables. Tables such as R301.2(1) climatic and geographic design criteria and the Chapter 5 to 8 span tables answer many questions on their own.
- Read exceptions. Many IRC answers sit in an exception, such as the 5 sq ft grade-floor escape opening or the sprinklered townhouse wall.
- Flag and move on. If a lookup takes more than 3 minutes, mark it and come back after the easier items.
Practise with the same printed edition you will bring, so your tabs and highlights match the exam.
Floors, Walls and Roofs: Key IRC Numbers
- Joist notches and holes (R502.8.1): notches up to one-sixth of the depth, none in the middle third of the span, and up to one-fourth at the ends. Holes up to one-third of the depth, at least 2 in from the edges.
- Slabs (R506): 3-1/2 in minimum, with a 4 in base course below grade and a 10-mil Class A vapor retarder lapped 6 in.
- Studs (R602.6): notches up to 25 percent in bearing walls and 40 percent in nonbearing walls. Bored holes up to 60 percent, 5/8 in from the edge, and the stud is doubled if the hole is over 40 percent in a bearing wall.
- Top plates (R602.3.2, R602.6.1): end joints offset 24 in. A cut over 50 percent of the width needs a 16 ga strap that extends 6 in past the opening.
- Coverings (R703): one layer of water-resistive barrier and shingle-fashion flashing. The stucco weep screed sits 4 in above earth. Veneer ties are spaced 32 in horizontally and 24 in vertically.
- Roofs (R802–R807): 1 in ridge board, 1/150 attic ventilation (1/300 by exception), a 22×30 in attic access and 30 in headroom.
Is the ICC B1 Exam Hard?
ICC doesn't publish pass rates. You have 2 minutes per question, and the exam is open book, so the challenge is finding answers in the code quickly. Tab your IRC by chapter and table, and practise looking things up against the clock.
State and Local Differences
Jurisdictions adopt different IRC editions, often with amendments. Buy the B1 for the code year your employer uses. Some states also run their own inspector licensing on top of ICC certification, so confirm with your state or local building department.
ICC B1 Study Plan
- Week 1: Read Chapters 3 and 4 and tab the tables.
- Week 2: Study Chapters 5 to 8 on floors, walls and roofs (55 percent of the exam combined).
- Week 3: Take our ICC B1 Residential Building Inspector Practice Test and a timed ICC B1 Residential Building Inspector Full Mock Exam.
How Our ICC B1 Questions Are Built
All 287 questions quote the 2021 IRC clause they rest on. They are not ICC exam items. For a related trade exam, see our Home Inspector Exam Guide.
Frequently Asked Questions
How many questions are on the ICC B1 Residential Building Inspector exam?
60 multiple-choice questions, with a 2-hour limit. The exam is open book.
What score do I need to pass the ICC B1 exam?
A scaled score of 75. That is not 75 percent correct. ICC adjusts scores for each exam version's difficulty,.
How much does the ICC B1 exam cost?
ICC's exam shop lists the B1 at $320. The purchase is final and valid for 365 days. Check the shop for current pricing before you buy.
Is the ICC B1 exam open book?
Yes. ICC's B1 outline says the exam is open book, and the reference is the International Residential Code. Choose the code year when you purchase.
How many times can I retake the ICC B1 exam?
For national exams, ICC allows six attempts within six months, and you pay the fee each time. After six attempts, you wait six months from the first attempt before registering again.
Is the B1 hard?
ICC publishes no pass rate. With 60 questions in 120 minutes you have 2 minutes per question, so knowing where things are in the IRC matters as much as knowing the numbers.
Which code year is on the exam?
ICC sells the B1 by code year. Choose the edition your jurisdiction uses, then study that edition.
What is the difference between the B1 and the B2?
The B1 covers one- and two-family dwellings, townhouses up to three stories and accessory structures under the IRC. The B2 Commercial Building Inspector is a separate exam.
Do states require the ICC B1?
Many jurisdictions accept or require ICC certifications, but rules vary by state and city. Check with your state or local building department.
What are the most-tested IRC numbers?
Wall construction (27 percent) and footings and foundations (16 percent) carry the most weight. Learn the egress, stair and guard numbers too.
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