AR DW Drywall Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the standard thickness for residential drywall used on interior
walls?
A. 1/2 inch
B. 3/8 inch
C. 5/8 inch
D. 3/4 inch
Answer: 5/8 inch
Rationale: 5/8 inch drywall is commonly used for interior walls due to its
strength and fire resistance. Thinner sheets like 1/2 inch are also used, but
5/8 inch is the standard for durability.
2. Which tool is primarily used to cut drywall sheets?
A. Hammer
B. Utility knife
C. Circular saw
D. Screwdriver
Answer: Utility knife
Rationale: A utility knife is the preferred tool because it provides clean,
straight cuts without generating dust or damaging the wall surface.
,3. What type of joint compound is best for embedding drywall tape?
A. Setting-type compound
B. All-purpose joint compound
C. Lightweight spackling
D. Latex caulk
Answer: All-purpose joint compound
Rationale: All-purpose joint compound is suitable for embedding tape and
finishing joints due to its balance of workability and adhesion.
4. What is the correct spacing for drywall screws on vertical walls?
A. 6 inches
B. 8 inches
C. 12 inches
D. 16 inches
Answer: 12 inches
Rationale: For standard interior walls, screws are spaced 12 inches apart
vertically to ensure secure attachment without overfastening.
5. What is the main purpose of a vapor barrier behind drywall?
A. To support drywall weight
B. To provide fire resistance
C. To prevent moisture penetration
D. To improve insulation R-value
Answer: To prevent moisture penetration
Rationale: Vapor barriers are installed to protect walls from moisture,
which can lead to mold, mildew, and structural damage.
6. Which type of drywall is recommended for high-humidity areas like
bathrooms?
A. Standard drywall
,B. Greenboard or moisture-resistant drywall
C. Fire-rated drywall
D. Impact-resistant drywall
Answer: Greenboard or moisture-resistant drywall
Rationale: Greenboard is specifically designed to resist moisture, making it
suitable for bathrooms and other humid environments.
7. How far should drywall panels be offset at the end joints on adjoining
sheets?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Answer: 12 inches
Rationale: Offsetting joints by at least 12 inches reduces the risk of visible
seams and enhances wall stability.
8. What is the maximum spacing for ceiling drywall screws?
A. 8 inches
B. 12 inches
C. 16 inches
D. 24 inches
Answer: 12 inches
Rationale: Ceiling drywall requires screws every 12 inches to prevent
sagging due to gravity.
9. When finishing drywall, what is the purpose of sanding between coats
of joint compound?
A. To strengthen the wall
B. To apply primer
, C. To smooth the surface for painting
D. To embed tape
Answer: To smooth the surface for painting
Rationale: Sanding ensures a smooth, even surface by removing ridges,
bubbles, or imperfections before the next coat.
10. Which drywall type provides additional fire resistance?
A. Greenboard
B. Type X drywall
C. Standard drywall
D. Lightweight drywall
Answer: Type X drywall
Rationale: Type X drywall contains glass fibers that increase fire resistance,
commonly used in fire-rated assemblies.
11. What is the recommended length of drywall screws for 1/2 inch
drywall over wood studs?
A. 1 inch
B. 1 1/4 inches
C. 1 1/2 inches
D. 2 inches
Answer: 1 1/4 inches
Rationale: Screws should penetrate the stud by at least 5/8 inch for a secure
hold, which 1 1/4-inch screws achieve for 1/2-inch drywall.
12. Which type of drywall tape is preferred for inside corners?
A. Paper tape
B. Fiberglass mesh tape
C. Corner bead tape
D. Metal tape
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the standard thickness for residential drywall used on interior
walls?
A. 1/2 inch
B. 3/8 inch
C. 5/8 inch
D. 3/4 inch
Answer: 5/8 inch
Rationale: 5/8 inch drywall is commonly used for interior walls due to its
strength and fire resistance. Thinner sheets like 1/2 inch are also used, but
5/8 inch is the standard for durability.
2. Which tool is primarily used to cut drywall sheets?
A. Hammer
B. Utility knife
C. Circular saw
D. Screwdriver
Answer: Utility knife
Rationale: A utility knife is the preferred tool because it provides clean,
straight cuts without generating dust or damaging the wall surface.
,3. What type of joint compound is best for embedding drywall tape?
A. Setting-type compound
B. All-purpose joint compound
C. Lightweight spackling
D. Latex caulk
Answer: All-purpose joint compound
Rationale: All-purpose joint compound is suitable for embedding tape and
finishing joints due to its balance of workability and adhesion.
4. What is the correct spacing for drywall screws on vertical walls?
A. 6 inches
B. 8 inches
C. 12 inches
D. 16 inches
Answer: 12 inches
Rationale: For standard interior walls, screws are spaced 12 inches apart
vertically to ensure secure attachment without overfastening.
5. What is the main purpose of a vapor barrier behind drywall?
A. To support drywall weight
B. To provide fire resistance
C. To prevent moisture penetration
D. To improve insulation R-value
Answer: To prevent moisture penetration
Rationale: Vapor barriers are installed to protect walls from moisture,
which can lead to mold, mildew, and structural damage.
6. Which type of drywall is recommended for high-humidity areas like
bathrooms?
A. Standard drywall
,B. Greenboard or moisture-resistant drywall
C. Fire-rated drywall
D. Impact-resistant drywall
Answer: Greenboard or moisture-resistant drywall
Rationale: Greenboard is specifically designed to resist moisture, making it
suitable for bathrooms and other humid environments.
7. How far should drywall panels be offset at the end joints on adjoining
sheets?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Answer: 12 inches
Rationale: Offsetting joints by at least 12 inches reduces the risk of visible
seams and enhances wall stability.
8. What is the maximum spacing for ceiling drywall screws?
A. 8 inches
B. 12 inches
C. 16 inches
D. 24 inches
Answer: 12 inches
Rationale: Ceiling drywall requires screws every 12 inches to prevent
sagging due to gravity.
9. When finishing drywall, what is the purpose of sanding between coats
of joint compound?
A. To strengthen the wall
B. To apply primer
, C. To smooth the surface for painting
D. To embed tape
Answer: To smooth the surface for painting
Rationale: Sanding ensures a smooth, even surface by removing ridges,
bubbles, or imperfections before the next coat.
10. Which drywall type provides additional fire resistance?
A. Greenboard
B. Type X drywall
C. Standard drywall
D. Lightweight drywall
Answer: Type X drywall
Rationale: Type X drywall contains glass fibers that increase fire resistance,
commonly used in fire-rated assemblies.
11. What is the recommended length of drywall screws for 1/2 inch
drywall over wood studs?
A. 1 inch
B. 1 1/4 inches
C. 1 1/2 inches
D. 2 inches
Answer: 1 1/4 inches
Rationale: Screws should penetrate the stud by at least 5/8 inch for a secure
hold, which 1 1/4-inch screws achieve for 1/2-inch drywall.
12. Which type of drywall tape is preferred for inside corners?
A. Paper tape
B. Fiberglass mesh tape
C. Corner bead tape
D. Metal tape
