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GEORGIA RESIDENTIAL-BASIC
CONTRACTOR — FLOORING-FOCUSED
PRACTICE QUESTIONS WITH VERIFIED
ANSWERS & COMPLETE RATIONALES
**1. What is the minimum subfloor thickness required for wood
floor framing under the IRC?**
A. 1/2 inch
B. 5/8 inch
C. 3/4 inch
D. 1 inch
**Correct answer:** C
**Rationale:** The IRC requires a minimum 3/4-inch wood
subfloor for residential floor framing. Plywood or OSB panels
are typically installed with the long dimension perpendicular to
the joists.
--
**2. What is the standard maximum spacing for floor joists
under a 3/4-inch wood subfloor in residential construction?**
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A. 12 inches on center
B. 16 inches on center
C. 24 inches on center
D. 32 inches on center
**Correct answer:** B
**Rationale:** The IRC specifies a maximum floor joist spacing
of 16 inches on center for typical residential loading conditions
with 3/4-inch subfloor panels.
--
**3. Which type of flooring requires the most stringent subfloor
flatness tolerance?**
A. Carpet
B. Vinyl sheet
C. Large-format tile
D. Hardwood strip
**Correct answer:** C
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**Rationale:** Large-format tile (typically 12" × 12" or larger)
requires a subfloor flatness tolerance of no more than 1/8 inch
in 10 feet. Carpet and vinyl are more forgiving of minor subfloor
variations.
--
**4. What is the minimum thickness of plywood underlayment
required for a ceramic tile installation?**
A. 1/4 inch
B. 3/8 inch
C. 1/2 inch
D. 5/8 inch
**Correct answer:** C
**Rationale:** A minimum 1/2-inch plywood or cement backer
board is required for ceramic tile installations over wood
subfloors to prevent deflection and cracking.
--
**5. What type of underlayment is generally NOT
recommended beneath hardwood flooring?**
GEORGIA RESIDENTIAL-BASIC
CONTRACTOR — FLOORING-FOCUSED
PRACTICE QUESTIONS WITH VERIFIED
ANSWERS & COMPLETE RATIONALES
**1. What is the minimum subfloor thickness required for wood
floor framing under the IRC?**
A. 1/2 inch
B. 5/8 inch
C. 3/4 inch
D. 1 inch
**Correct answer:** C
**Rationale:** The IRC requires a minimum 3/4-inch wood
subfloor for residential floor framing. Plywood or OSB panels
are typically installed with the long dimension perpendicular to
the joists.
--
**2. What is the standard maximum spacing for floor joists
under a 3/4-inch wood subfloor in residential construction?**
,2 | Page
A. 12 inches on center
B. 16 inches on center
C. 24 inches on center
D. 32 inches on center
**Correct answer:** B
**Rationale:** The IRC specifies a maximum floor joist spacing
of 16 inches on center for typical residential loading conditions
with 3/4-inch subfloor panels.
--
**3. Which type of flooring requires the most stringent subfloor
flatness tolerance?**
A. Carpet
B. Vinyl sheet
C. Large-format tile
D. Hardwood strip
**Correct answer:** C
, 3 | Page
**Rationale:** Large-format tile (typically 12" × 12" or larger)
requires a subfloor flatness tolerance of no more than 1/8 inch
in 10 feet. Carpet and vinyl are more forgiving of minor subfloor
variations.
--
**4. What is the minimum thickness of plywood underlayment
required for a ceramic tile installation?**
A. 1/4 inch
B. 3/8 inch
C. 1/2 inch
D. 5/8 inch
**Correct answer:** C
**Rationale:** A minimum 1/2-inch plywood or cement backer
board is required for ceramic tile installations over wood
subfloors to prevent deflection and cracking.
--
**5. What type of underlayment is generally NOT
recommended beneath hardwood flooring?**
