Nevada C-20 Tiling Contractor Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of a substrate in tile
installation?
A. To provide aesthetic appeal
B. To increase thermal insulation
C. To provide a stable, level surface for tiles
D. To reduce sound transmission
A substrate ensures that tiles have a stable, level, and durable
surface to adhere to, preventing cracks and unevenness in the
finished installation.
2. What is the recommended maximum moisture content for a concrete
slab before installing ceramic tile?
A. 5%
B. 8%
C. 3%
D. 10%
Excessive moisture in a concrete slab can prevent proper adhesion of
tile and thin-set mortar, leading to failure over time. The industry
standard is typically around 3% moisture content.
3. Which type of tile is most suitable for high-moisture areas like
bathrooms?
A. Natural stone
B. Porcelain tile
C. Terrazzo
D. Vinyl
, Porcelain tile is highly dense and water-resistant, making it ideal for
wet environments, unlike natural stone, which may absorb water.
4. What is the primary function of grout in a tile installation?
A. To increase the strength of tiles
B. To fill joints between tiles and prevent water penetration
C. To act as a thermal insulator
D. To enhance color contrast
Grout fills the gaps between tiles, stabilizes the installation, and
prevents water from seeping beneath the tiles, which can cause
damage.
5. Which method is most commonly used to ensure tiles are level during
installation?
A. Laser cutting tiles
B. Using a leveling system or spacers
C. Applying additional adhesive
D. Sanding tile edges
Leveling systems and spacers maintain uniform spacing and
alignment, preventing lippage and ensuring a flat surface.
6. What is the primary difference between ceramic and porcelain tiles?
A. Porcelain tiles are always larger
B. Porcelain tiles have a lower water absorption rate
C. Ceramic tiles are more durable
D. Ceramic tiles cannot be used outdoors
Porcelain tiles are denser and less porous than ceramic tiles, making
them more resistant to water, stains, and wear.
7. Which adhesive is most appropriate for installing large-format
porcelain tiles on a concrete floor?
A. Epoxy grout
B. Mastic
C. Modified thin-set mortar
D. Silicone caulk
Modified thin-set mortar contains polymers that improve bonding
strength, flexibility, and water resistance, especially for large-format
tiles.
, 8. What is the minimum thickness for a cement backer board under tile
in wet areas?
A. 1/4 inch
B. 1/2 inch
C. 3/4 inch
D. 1 inch
A 1/2 inch cement backer board provides adequate strength and
stability for tile installations in wet areas, meeting industry
standards.
9. Which of the following is a common cause of tile cracking after
installation?
A. Using too much grout
B. Substrate movement or inadequate expansion joints
C. Excessive cleaning
D. Installing tile on a smooth surface
Tile cracking often occurs when the substrate moves or expands
without proper joints to absorb stress, leading to fractures in the
tiles.
10. When installing floor tile, which layout technique helps
minimize small, narrow cuts at edges?
A. Random layout
B. Centerline layout
C. Herringbone layout
D. Diagonal layout
A centerline layout balances the tiles from the center outward,
minimizing thin, awkward cuts at the walls and ensuring a more
professional appearance.
11. What is the purpose of a waterproof membrane in a shower
installation?
A. To strengthen the tile
B. To reduce noise
C. To prevent water from penetrating the substrate
D. To enhance adhesion of grout
Waterproof membranes create a barrier that protects the subfloor
and walls from moisture, preventing mold and structural damage.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of a substrate in tile
installation?
A. To provide aesthetic appeal
B. To increase thermal insulation
C. To provide a stable, level surface for tiles
D. To reduce sound transmission
A substrate ensures that tiles have a stable, level, and durable
surface to adhere to, preventing cracks and unevenness in the
finished installation.
2. What is the recommended maximum moisture content for a concrete
slab before installing ceramic tile?
A. 5%
B. 8%
C. 3%
D. 10%
Excessive moisture in a concrete slab can prevent proper adhesion of
tile and thin-set mortar, leading to failure over time. The industry
standard is typically around 3% moisture content.
3. Which type of tile is most suitable for high-moisture areas like
bathrooms?
A. Natural stone
B. Porcelain tile
C. Terrazzo
D. Vinyl
, Porcelain tile is highly dense and water-resistant, making it ideal for
wet environments, unlike natural stone, which may absorb water.
4. What is the primary function of grout in a tile installation?
A. To increase the strength of tiles
B. To fill joints between tiles and prevent water penetration
C. To act as a thermal insulator
D. To enhance color contrast
Grout fills the gaps between tiles, stabilizes the installation, and
prevents water from seeping beneath the tiles, which can cause
damage.
5. Which method is most commonly used to ensure tiles are level during
installation?
A. Laser cutting tiles
B. Using a leveling system or spacers
C. Applying additional adhesive
D. Sanding tile edges
Leveling systems and spacers maintain uniform spacing and
alignment, preventing lippage and ensuring a flat surface.
6. What is the primary difference between ceramic and porcelain tiles?
A. Porcelain tiles are always larger
B. Porcelain tiles have a lower water absorption rate
C. Ceramic tiles are more durable
D. Ceramic tiles cannot be used outdoors
Porcelain tiles are denser and less porous than ceramic tiles, making
them more resistant to water, stains, and wear.
7. Which adhesive is most appropriate for installing large-format
porcelain tiles on a concrete floor?
A. Epoxy grout
B. Mastic
C. Modified thin-set mortar
D. Silicone caulk
Modified thin-set mortar contains polymers that improve bonding
strength, flexibility, and water resistance, especially for large-format
tiles.
, 8. What is the minimum thickness for a cement backer board under tile
in wet areas?
A. 1/4 inch
B. 1/2 inch
C. 3/4 inch
D. 1 inch
A 1/2 inch cement backer board provides adequate strength and
stability for tile installations in wet areas, meeting industry
standards.
9. Which of the following is a common cause of tile cracking after
installation?
A. Using too much grout
B. Substrate movement or inadequate expansion joints
C. Excessive cleaning
D. Installing tile on a smooth surface
Tile cracking often occurs when the substrate moves or expands
without proper joints to absorb stress, leading to fractures in the
tiles.
10. When installing floor tile, which layout technique helps
minimize small, narrow cuts at edges?
A. Random layout
B. Centerline layout
C. Herringbone layout
D. Diagonal layout
A centerline layout balances the tiles from the center outward,
minimizing thin, awkward cuts at the walls and ensuring a more
professional appearance.
11. What is the purpose of a waterproof membrane in a shower
installation?
A. To strengthen the tile
B. To reduce noise
C. To prevent water from penetrating the substrate
D. To enhance adhesion of grout
Waterproof membranes create a barrier that protects the subfloor
and walls from moisture, preventing mold and structural damage.
