CA C9 Drywall Contractor Exam

CA C9 Drywall Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• Which of the following is the standard thickness for residential interior

drywall?

• 1/4 inch
• 1/2 inch
• 5/8 inch
• 3/4 inch
• 1/2 inch

Rationale: 1/2 inch drywall is the most commonly used thickness for

residential interior walls and ceilings due to its balance of strength and ease of installation.

• What is the purpose of using corner bead on drywall?
• To reduce sound transmission
• To strengthen and protect corners
• To improve fire resistance
• To attach drywall to framing
• To strengthen and protect corners

Rationale: Corner bead provides a straight edge and protects drywall

corners from impact damage.

• Which type of drywall is specifically designed for moisture-prone areas

like bathrooms?

• Type X
• Standard
• Greenboard
• Blueboard
• Greenboard 1 / 3

Rationale: Greenboard is moisture-resistant drywall, typically used in

areas with high humidity but not direct water exposure.

4. Type X drywall is primarily used for:

• Soundproofing
• Fire resistance
• Moisture resistance
• Exterior sheathing
• Fire resistance

Rationale: Type X drywall contains special additives that improve fire

resistance, making it suitable for fire-rated assemblies.

5. The proper spacing for drywall screws on walls is typically:

• 6 inches
• 12 inches
• 16 inches
• 24 inches
• 16 inches

Rationale: Screws are usually spaced 16 inches apart on walls to

ensure secure attachment without over-fastening.

• What tool is used to cut drywall cleanly?
• Jigsaw
• Drywall knife
• Utility knife
• Circular saw
• Utility knife

Rationale: A utility knife is used to score and snap drywall sheets

cleanly along straight lines.

• When hanging drywall on ceilings, which method is recommended?
• Horizontal installation
• Vertical installation
• Start from the center
• Start from the edges
• Horizontal installation

Rationale: Ceiling drywall is typically installed horizontally across

joists to reduce sagging and increase support.

• Joint compound should be applied in how many coats for a smooth

finish?

• One 2 / 3

• Two
• Three
• Four
• Three

Rationale: Standard drywall finishing uses three coats—taping,

filling, and final finishing—for a smooth surface.

• Which of the following is not a drywall finishing tool?
• Taping knife
• Mud pan
• Hawk
• Screw gun
• Screw gun

Rationale: While a screw gun is used for fastening, it is not a

finishing tool. Taping knives, mud pans, and hawks are used for applying and smoothing joint compound.

10. Drywall adhesive is primarily used to:

• Replace screws entirely
• Reduce the number of fasteners
• Waterproof the drywall
• Fireproof the drywall
• Reduce the number of fasteners

Rationale: Adhesive helps secure drywall to framing, reducing the

number of mechanical fasteners needed and minimizing nail pops.

• Which of the following is the main cause of drywall cracking?
• Poor joint compound
• Framing movement
• Improper screw placement
• Paint type
• Framing movement

Rationale: Cracks typically occur due to wood framing expansion

and contraction, especially in corners and seams.

• What is the purpose of using a drywall rasp?
• To cut sheets
• To smooth rough edges
• To attach drywall to studs
• To mix joint compound
• To smooth rough edges
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