California C-9 Drywall Contractor
Practice Exam | Questions,
Verified Answers & Detailed
Rationales | Complete CSLB
Contractor License Exam Prep
Study Guide | Updated 2026
Planning and Estimating
1. Before estimating the quantity of drywall needed for a
project, what should be reviewed first?
A. Paint colour schedule
B. Construction plans and specifications
C. Appliance manufacturer's warranty
D. Landscaping plan
Answer: Construction plans and specifications
Rationale: The plans and specifications establish wall
dimensions, ceiling conditions, board types,
thicknesses, assemblies, and other requirements
needed for an accurate estimate.
2. A wall is 12 feet long and 8 feet high. What is the wall's
approximate surface area?
A. 80 square feet
B. 88 square feet
C. 96 square feet
D. 108 square feet
Answer: 96 square feet
Rationale: Multiply length by height: 12 × 8 = 96 square
feet.
, 3. When estimating drywall, why should openings such as
doors and windows be considered?
A. They increase the required board thickness
B. They determine the paint colour
C. They reduce the amount of board required for the
wall surface
D. They determine the framing material
Answer: They reduce the amount of board required for
the wall surface
Rationale: Doors and windows occupy portions of the
wall that do not require full sheets of drywall, although
waste around openings must still be considered.
4. A room requires 1,200 square feet of drywall. If 10% is
added for waste, how much should be estimated?
A. 1,210 square feet
B. 1,250 square feet
C. 1,320 square feet
D. 1,400 square feet
Answer: 1,320 square feet
Rationale: Ten percent of 1,200 is 120. Adding 120 to
1,200 gives 1,320 square feet.
5. What is the primary purpose of a material take-off?
A. Determine employee wages
B. Determine quantities of materials required for the
project
C. Determine the building's property value
D. Establish the customer's credit rating
Answer: Determine quantities of materials required for
the project
,Rationale: A take-off identifies the quantities of drywall,
framing, fasteners, tape, compound, trims, and related
materials needed.
6. When plans conflict with written specifications, the
contractor should generally:
A. Ignore both documents
B. Use whichever option costs less
C. Clarify the conflict before proceeding
D. Let the drywall installer decide
Answer: Clarify the conflict before proceeding
Rationale: Unresolved conflicts can cause rework,
delays, and disputes. The appropriate design authority
should clarify the requirement before installation.
7. Which factor most directly affects the amount of drywall
compound required?
A. Exterior landscaping
B. Roof color
C. Number and type of joints and finish requirements
D. Number of electrical meters
Answer: Number and type of joints and finish
requirements
Rationale: More joints, corners, fastener depressions,
levels of finish, and textures can significantly increase
compound requirements.
8. Which drywall thickness is commonly used for many
standard wall applications?
A. 1/8 inch
B. 1/4 inch
, C. 1/2 inch
D. 1 inch
Answer: 1/2 inch
Rationale: 1/2-inch gypsum board is widely used for
standard interior wall applications, although the
specified assembly determines the required thickness.
9. A contractor needs 80 sheets of drywall and estimates
12.5% waste. Approximately how many sheets should be
ordered?
A. 82
B. 88
C. 90
D. 100
Answer: 90 sheets
Rationale: 80 × 12.5% = 10 sheets of waste. Therefore,
approximately 90 sheets should be allowed.
10. What is the best source for determining the required
fire-resistance rating of a specified wall assembly?
A. The drywall manufacturer's advertising
B. The worker's preference
C. The plans, specifications, and approved tested
assembly
D. The paint manufacturer's instructions
Answer: The plans, specifications, and approved tested
assembly
Rationale: Fire-rated construction must conform to the
specified and approved assembly, including board type,
thickness, framing, fasteners, joints, and other
components.
Practice Exam | Questions,
Verified Answers & Detailed
Rationales | Complete CSLB
Contractor License Exam Prep
Study Guide | Updated 2026
Planning and Estimating
1. Before estimating the quantity of drywall needed for a
project, what should be reviewed first?
A. Paint colour schedule
B. Construction plans and specifications
C. Appliance manufacturer's warranty
D. Landscaping plan
Answer: Construction plans and specifications
Rationale: The plans and specifications establish wall
dimensions, ceiling conditions, board types,
thicknesses, assemblies, and other requirements
needed for an accurate estimate.
2. A wall is 12 feet long and 8 feet high. What is the wall's
approximate surface area?
A. 80 square feet
B. 88 square feet
C. 96 square feet
D. 108 square feet
Answer: 96 square feet
Rationale: Multiply length by height: 12 × 8 = 96 square
feet.
, 3. When estimating drywall, why should openings such as
doors and windows be considered?
A. They increase the required board thickness
B. They determine the paint colour
C. They reduce the amount of board required for the
wall surface
D. They determine the framing material
Answer: They reduce the amount of board required for
the wall surface
Rationale: Doors and windows occupy portions of the
wall that do not require full sheets of drywall, although
waste around openings must still be considered.
4. A room requires 1,200 square feet of drywall. If 10% is
added for waste, how much should be estimated?
A. 1,210 square feet
B. 1,250 square feet
C. 1,320 square feet
D. 1,400 square feet
Answer: 1,320 square feet
Rationale: Ten percent of 1,200 is 120. Adding 120 to
1,200 gives 1,320 square feet.
5. What is the primary purpose of a material take-off?
A. Determine employee wages
B. Determine quantities of materials required for the
project
C. Determine the building's property value
D. Establish the customer's credit rating
Answer: Determine quantities of materials required for
the project
,Rationale: A take-off identifies the quantities of drywall,
framing, fasteners, tape, compound, trims, and related
materials needed.
6. When plans conflict with written specifications, the
contractor should generally:
A. Ignore both documents
B. Use whichever option costs less
C. Clarify the conflict before proceeding
D. Let the drywall installer decide
Answer: Clarify the conflict before proceeding
Rationale: Unresolved conflicts can cause rework,
delays, and disputes. The appropriate design authority
should clarify the requirement before installation.
7. Which factor most directly affects the amount of drywall
compound required?
A. Exterior landscaping
B. Roof color
C. Number and type of joints and finish requirements
D. Number of electrical meters
Answer: Number and type of joints and finish
requirements
Rationale: More joints, corners, fastener depressions,
levels of finish, and textures can significantly increase
compound requirements.
8. Which drywall thickness is commonly used for many
standard wall applications?
A. 1/8 inch
B. 1/4 inch
, C. 1/2 inch
D. 1 inch
Answer: 1/2 inch
Rationale: 1/2-inch gypsum board is widely used for
standard interior wall applications, although the
specified assembly determines the required thickness.
9. A contractor needs 80 sheets of drywall and estimates
12.5% waste. Approximately how many sheets should be
ordered?
A. 82
B. 88
C. 90
D. 100
Answer: 90 sheets
Rationale: 80 × 12.5% = 10 sheets of waste. Therefore,
approximately 90 sheets should be allowed.
10. What is the best source for determining the required
fire-resistance rating of a specified wall assembly?
A. The drywall manufacturer's advertising
B. The worker's preference
C. The plans, specifications, and approved tested
assembly
D. The paint manufacturer's instructions
Answer: The plans, specifications, and approved tested
assembly
Rationale: Fire-rated construction must conform to the
specified and approved assembly, including board type,
thickness, framing, fasteners, joints, and other
components.
