Nevada C-20 Tiling Contractor Exam
Practice Test Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
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1. What is the primary purpose of a substrate in tile installation?
A. To color the tile
B. To support and stabilize tile installation
C. To waterproof grout
D. To seal joints
Correct Answer: B. To support and stabilize tile installation
Rationale: The substrate provides a stable, level, and structurally sound surface
for tile adhesion and long-term performance.
2. Which tool is commonly used to spread thinset mortar?
A. Hammer
B. Notched trowel
C. Chalk line
D. Screwdriver
,Correct Answer: B. Notched trowel
Rationale: A notched trowel ensures even distribution and proper thickness of
adhesive mortar.
3. What is the minimum recommended curing time for cement-based thinset
before grouting?
A. 1 hour
B. 4 hours
C. 24 hours
D. 7 days
Correct Answer: C. 24 hours
Rationale: Thinset typically requires at least 24 hours to cure before grouting
begins.
4. What material is commonly used for grout joints in ceramic tile
installations?
A. Epoxy resin
B. Portland cement
C. Steel mesh
D. Silicone oil
Correct Answer: B. Portland cement
Rationale: Cement-based grout is standard for most ceramic tile installations
due to strength and affordability.
5. What is the purpose of expansion joints in tile work?
A. Decoration
B. Prevent cracking from movement
C. Increase tile strength
D. Reduce grout usage
, Correct Answer: B. Prevent cracking from movement
Rationale: Expansion joints accommodate thermal and structural movement,
preventing tile failure.
6. Which tile type is most water-resistant?
A. Porcelain
B. Terrazzo
C. Limestone
D. Slate
Correct Answer: A. Porcelain
Rationale: Porcelain tiles have very low porosity, making them highly water-
resistant.
7. What is the function of back buttering tile?
A. Coloring tile edges
B. Increasing adhesive bond strength
C. Reducing tile weight
D. Preventing grout stains
Correct Answer: B. Increasing adhesive bond strength
Rationale: Back buttering ensures full mortar coverage for stronger adhesion.
8. What is the recommended minimum slope for shower floors?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Correct Answer: C. 1/4 inch per foot
Rationale: Proper drainage requires a slope of at least 1/4 inch per foot.
Practice Test Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A Instant Download
1. What is the primary purpose of a substrate in tile installation?
A. To color the tile
B. To support and stabilize tile installation
C. To waterproof grout
D. To seal joints
Correct Answer: B. To support and stabilize tile installation
Rationale: The substrate provides a stable, level, and structurally sound surface
for tile adhesion and long-term performance.
2. Which tool is commonly used to spread thinset mortar?
A. Hammer
B. Notched trowel
C. Chalk line
D. Screwdriver
,Correct Answer: B. Notched trowel
Rationale: A notched trowel ensures even distribution and proper thickness of
adhesive mortar.
3. What is the minimum recommended curing time for cement-based thinset
before grouting?
A. 1 hour
B. 4 hours
C. 24 hours
D. 7 days
Correct Answer: C. 24 hours
Rationale: Thinset typically requires at least 24 hours to cure before grouting
begins.
4. What material is commonly used for grout joints in ceramic tile
installations?
A. Epoxy resin
B. Portland cement
C. Steel mesh
D. Silicone oil
Correct Answer: B. Portland cement
Rationale: Cement-based grout is standard for most ceramic tile installations
due to strength and affordability.
5. What is the purpose of expansion joints in tile work?
A. Decoration
B. Prevent cracking from movement
C. Increase tile strength
D. Reduce grout usage
, Correct Answer: B. Prevent cracking from movement
Rationale: Expansion joints accommodate thermal and structural movement,
preventing tile failure.
6. Which tile type is most water-resistant?
A. Porcelain
B. Terrazzo
C. Limestone
D. Slate
Correct Answer: A. Porcelain
Rationale: Porcelain tiles have very low porosity, making them highly water-
resistant.
7. What is the function of back buttering tile?
A. Coloring tile edges
B. Increasing adhesive bond strength
C. Reducing tile weight
D. Preventing grout stains
Correct Answer: B. Increasing adhesive bond strength
Rationale: Back buttering ensures full mortar coverage for stronger adhesion.
8. What is the recommended minimum slope for shower floors?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1/2 inch per foot
Correct Answer: C. 1/4 inch per foot
Rationale: Proper drainage requires a slope of at least 1/4 inch per foot.
