CSLB Class B Exam Study Guide (2026)
Everything the California CSLB Class B General Building Trade Exam tests, topic by topic: what each section covers, the facts that come up most, and how to study it. Pair it with the free 15-question practice test.
The exam at a glance
| Questions | About 115 multiple-choice questions |
|---|---|
| Time | About 3.5 hours |
| Passing score | Set by CSLB per exam form (plan for 70%+) |
| Format | Closed book |
| Licensing body | Contractors State License Board (CSLB) |
| Test provider | PSI |
Mind map: the whole exam on one screen
1. License Scope and Planning
This topic covers what a Class B General Building contractor may legally contract for and how a project is planned and scheduled. Scope questions are common because taking the wrong kind of contract is a licensing violation, and scheduling questions test the critical path method.
Key facts
- A B contractor's principal business is any structure that needs at least two unrelated building trades or crafts to build (B&P Code §7057(a)).
- A B contractor may take a prime contract or subcontract for a framing or carpentry project by itself (B&P Code §7057(b)).
- Framing or carpentry cannot be counted as one of the two unrelated trades needed to take a multi-trade prime contract or subcontract (B&P Code §7057(b)).
- A B contractor may not contract for C-16 Fire Protection or C-57 Well Drilling work unless it holds that license or subcontracts it to a properly licensed contractor (B&P Code §7057(c)).
- A B-2 Residential Remodeling contractor works on existing residential wood frame structures and each contract must use at least three unrelated trades (B&P Code §7057.5).
- The critical path is the longest path through the schedule network. Activities on it have zero float, so any delay to them delays the whole project (critical path method).
- Float on a noncritical path equals the critical path duration minus that path's duration (critical path method).
Flashcards
Exam tip: When a question lists the trades on a job, cross out framing and carpentry first, then count what is left.
2. Estimating and Takeoffs
Estimating questions are math problems: volumes, areas, lumber, piece counts and pricing. A calculator is allowed, so most errors come from unit conversions and from confusing markup with margin.
Key facts
- Cubic yards = cubic feet divided by 27. Convert slab thickness from inches to feet before multiplying.
- Board feet = thickness (in) x width (in) x length (ft) divided by 12. A 2x12 that is 16 ft long holds 32 board feet.
- One roofing square covers 100 square feet of roof surface.
- A 4 ft x 8 ft sheet of drywall or plywood covers 32 square feet.
- Studs at 16 inches on center: wall length in inches divided by 16, plus 1 for the starting stud.
- Selling price for a target margin = cost divided by (1 minus margin). A 20 percent margin on $80,000 cost gives a $100,000 price.
- Markup is figured on cost and margin on selling price. A 25 percent markup on cost equals a 20 percent margin.
Flashcards
Exam tip: Before you calculate, convert every dimension to feet, and check whether the question asks for margin on price or markup on cost.
3. Site Work and Foundations
This topic covers grading, footing size and depth, anchoring the building to the foundation, and crawl space access and venting. California now uses the 2025 California Residential Code (CRC), based on the 2024 IRC, effective January 1, 2026.
Key facts
- The grade must fall at least 6 inches within the first 10 feet away from the foundation (CRC R401.3).
- Exterior footings must be at least 12 inches below undisturbed ground (CRC R403.1.4).
- Concrete footings must be at least 12 inches wide and 6 inches thick (CRC R403.1.1).
- Sill plates need 1/2-inch anchor bolts at no more than 6 feet on center, embedded at least 7 inches into concrete (CRC R403.1.6).
- Each plate section needs at least two bolts, with one bolt no more than 12 inches and no less than seven bolt diameters from each end (CRC R403.1.6).
- Under-floor vents must give at least 1 square foot of net area per 150 square feet of crawl space, with a vent within 3 feet of each corner (CRC R408.2).
- Crawl space access through the floor must be at least 18 in x 24 in. Through a perimeter wall it must be at least 16 in x 24 in (CRC R408.4).
Flashcards
Exam tip: Older study guides cite 2022 CRC section numbers, so learn the numbers themselves (6 in 10 ft, 12 inches deep, 6 ft bolts) rather than section labels.
Test yourself on these topics
Take the free 15-question CSLB Class B test, then save your results to unlock your Readiness Score and the mistakes bank.
4. Concrete and Moisture Control
Concrete questions test slab and footing minimums, reinforcing cover, and how water content affects strength. Moisture questions cover vapor retarders, ventilation and drainage that keep water out of the structure.
Key facts
- Concrete slab-on-ground floors must be at least 3-1/2 inches thick (CRC R506.1).
- A vapor retarder of at least 6-mil polyethylene, with joints lapped at least 6 inches, goes between the slab and the base course or subgrade (CRC R506.3.3).
Flashcards
Exam tip: If an answer choice says adding water to a mix improves strength, it is wrong.
5. Framing and Structural
This topic covers wood framing rules for joists, studs and plates, and the limits on cutting framing members for pipes and wires. These questions protect the load path, so the numbers are strict.
Key facts
- Joist ends need at least 1-1/2 inches of bearing on wood or metal and at least 3 inches on masonry or concrete (CRC R502.6).
- Notches in sawn joists may not exceed one-sixth of the depth and are not allowed in the middle one-third of the span. End notches may not exceed one-fourth of the depth (CRC R502.8.1).
Flashcards
Exam tip: Read whether the member is a joist or a stud and whether the wall is bearing, because each has a different cutting limit.
6. Stairs, Guards and Egress
This topic covers stair geometry, handrails, guards and emergency escape openings. California amends the IRC in places, so use the California numbers, such as the 42-inch guard height.
Key facts
- Maximum riser height is 7-3/4 inches and minimum tread depth is 10 inches, with no more than 3/8 inch variation in a flight (CRC R318.7.5.1 and R318.7.5.2).
- Stair headroom must be at least 6 ft 8 in, and stair width at least 36 inches above the handrail (CRC R318.7.1 and R318.7.2).
Flashcards
Exam tip: Do not mix up the 30-inch trigger for when a guard is required with the 42-inch height the guard must be.
7. Core Trades Coordination
A B contractor coordinates plumbing, electrical and mechanical work, so the exam asks basic layout and installation rules from the California Plumbing Code (CPC) and California Electrical Code (CEC). Know the fixture clearances and receptacle spacing that drive rough-in.
Key facts
- A water closet must be at least 15 inches from its center to a side wall, 30 inches center to center from a similar fixture, with 24 inches clear in front (CPC 402.5).
- Shower compartments need at least 1,024 square inches of interior area and must fit a 30-inch circle (CPC 408.6).
Flashcards
Exam tip: California uses the UPC-based plumbing code, so the front clearance at a toilet is 24 inches, not the 21 inches found in IRC-based codes.
8. Fire Safety and Finishes
This topic covers fire separation between the house and garage, fireblocking, safety glazing and common finish materials. These are life-safety rules, so inspectors and the exam treat them strictly.
Key facts
- Garage to dwelling separation needs at least 1/2-inch gypsum board on the garage side (CRC Table R302.6).
- Habitable rooms above a garage need at least 5/8-inch Type X gypsum board on the garage ceiling (CRC Table R302.6).
Flashcards
Exam tip: A door from a garage straight into a bedroom is never allowed, no matter how fire-rated the door is.
9. Jobsite Safety (Cal/OSHA)
California jobsites follow Cal/OSHA rules in Title 8 of the California Code of Regulations, which are sometimes stricter than federal OSHA. Expect questions on fall protection, trenches, ladders, injury reporting and safety meetings.
Key facts
- Fall protection systems must be worn where workers can fall more than 7-1/2 feet from a perimeter, edge or opening (8 CCR 1670(a)).
- Guardrail top rails must be 42 to 45 inches high (8 CCR 1620).
Flashcards
Exam tip: Federal OSHA uses 6 feet for construction fall protection, but this is a California exam, so use the general Cal/OSHA 7-1/2 foot trigger unless the question names a specific exception.
How to pass
- The B license requires work involving at least two unrelated trades (framing and carpentry don't count). Expect scope-of-license questions.
- Learn residential code numbers by heart: stairs, guards, egress, anchor bolts, fireblocking.
- Practice board-foot and concrete math without a reference book.
Frequently asked questions
How long should I study for the CSLB Class B exam?
Most working candidates need 4 to 8 weeks at 45 to 60 minutes a day. Book your exam once your Readiness Score has stayed at 80 or higher for about a week.
Is the CSLB Class B exam open book?
Closed book. Check the current candidate information bulletin from Contractors State License Board (CSLB) for the approved reference list and tabbing rules.
What score do I need to pass the CSLB Class B exam?
Set by CSLB per exam form (plan for 70%+). The exam has about 115 multiple-choice questions and a time limit of about 3.5 hours.
What are the most tested topics?
The outline covers license scope and planning, estimating and takeoffs, site work and foundations, concrete and moisture control, framing and structural, stairs, guards and egress, core trades coordination, fire safety and finishes, jobsite safety (cal/osha). Use the free practice test to see which ones you need most.
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Summarized from official candidate information and the statutes, codes and regulations cited, checked October 2026. Confirm current requirements with Contractors State License Board (CSLB).