CO Tile Contractor Exam Questions
And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the standard thickness of most ceramic wall tiles?
A) 3–4 mm
B) 5–6 mm
C) 7–8 mm
D) 9–10 mm
B) 5–6 mm
Rationale: Most ceramic wall tiles are manufactured between 5 and 6
mm thick, providing adequate strength while being lightweight for
wall installation.
2. Which trowel notch size is typically used for installing 12x12 inch floor
tiles?
A) 1/4 inch square notch
B) 1/8 inch V-notch
C) 1/2 inch square notch
D) 3/16 inch U-notch
C) 1/2 inch square notch
Rationale: Larger floor tiles require more adhesive coverage, and a
1/2 inch square-notched trowel ensures proper bed thickness and
adhesion.
3. What is the primary purpose of a cement backer board?
A) Decorative finish
B) Moisture resistance and tile support
C) Insulation
D) Soundproofing
B) Moisture resistance and tile support
, Rationale: Cement backer boards provide a stable, moisture-resistant
surface for tile installation, preventing warping and failure.
4. What is the maximum recommended spacing between expansion joints
in a tiled floor?
A) 8–10 feet
B) 12–16 feet
C) 20–25 feet
D) 30–35 feet
B) 12–16 feet
Rationale: Expansion joints prevent cracking due to thermal
expansion or substrate movement, and spacing of 12–16 feet is
standard.
5. Which adhesive type is best for installing porcelain tiles on a floor?
A) Mastic
B) Thin-set mortar
C) Epoxy paint
D) Cement plaster
B) Thin-set mortar
Rationale: Thin-set mortar provides strong adhesion and durability
for heavy-duty porcelain tiles, especially on floors.
6. What is the first step in preparing a concrete floor for tile installation?
A) Applying thin-set mortar
B) Cleaning and leveling the floor
C) Installing a backer board
D) Grouting
B) Cleaning and leveling the floor
Rationale: Proper cleaning and leveling remove debris, dust, and
uneven surfaces, ensuring proper adhesion and long-term
performance.
7. Which tool is most suitable for cutting ceramic tiles in straight lines?
A) Angle grinder
B) Tile cutter (manual snap cutter)
C) Jigsaw
D) Circular saw
B) Tile cutter (manual snap cutter)
Rationale: Manual tile cutters score and snap tiles cleanly along
straight lines without generating excessive dust.
, 8. What is the recommended grout joint width for most ceramic wall tiles?
A) 1/32 inch
B) 1/8–3/16 inch
C) 1/4–3/8 inch
D) 1/2 inch
B) 1/8–3/16 inch
Rationale: Wall tiles usually have narrow grout joints, typically 1/8 to
3/16 inch, to maintain appearance and prevent excessive grout
cracking.
9. Which type of tile is highly resistant to water and frost, making it ideal
for outdoor use?
A) Ceramic wall tile
B) Porcelain tile
C) Quarry tile
D) Vinyl tile
B) Porcelain tile
Rationale: Porcelain tiles have low water absorption and high
density, making them durable in outdoor and freeze-thaw conditions.
10. What is the purpose of a notched trowel?
A) Mix mortar
B) Spread adhesive evenly
C) Cut tiles
D) Measure grout joints
B) Spread adhesive evenly
Rationale: Notched trowels ensure an even layer of adhesive with
proper ridges for full tile contact and adhesion.
11. Which method is best for leveling large-format tiles?
A) Using shims under the tile
B) Using a self-leveling mortar
C) Hammering tiles into place
D) Ignoring slight unevenness
B) Using a self-leveling mortar
Rationale: Self-leveling mortar ensures a flat, even substrate suitable
for large-format tiles, reducing lippage.
12. What is “lippage” in tile installation?
A) Uneven grout lines
B) Uneven tile edges causing a height difference
And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. What is the standard thickness of most ceramic wall tiles?
A) 3–4 mm
B) 5–6 mm
C) 7–8 mm
D) 9–10 mm
B) 5–6 mm
Rationale: Most ceramic wall tiles are manufactured between 5 and 6
mm thick, providing adequate strength while being lightweight for
wall installation.
2. Which trowel notch size is typically used for installing 12x12 inch floor
tiles?
A) 1/4 inch square notch
B) 1/8 inch V-notch
C) 1/2 inch square notch
D) 3/16 inch U-notch
C) 1/2 inch square notch
Rationale: Larger floor tiles require more adhesive coverage, and a
1/2 inch square-notched trowel ensures proper bed thickness and
adhesion.
3. What is the primary purpose of a cement backer board?
A) Decorative finish
B) Moisture resistance and tile support
C) Insulation
D) Soundproofing
B) Moisture resistance and tile support
, Rationale: Cement backer boards provide a stable, moisture-resistant
surface for tile installation, preventing warping and failure.
4. What is the maximum recommended spacing between expansion joints
in a tiled floor?
A) 8–10 feet
B) 12–16 feet
C) 20–25 feet
D) 30–35 feet
B) 12–16 feet
Rationale: Expansion joints prevent cracking due to thermal
expansion or substrate movement, and spacing of 12–16 feet is
standard.
5. Which adhesive type is best for installing porcelain tiles on a floor?
A) Mastic
B) Thin-set mortar
C) Epoxy paint
D) Cement plaster
B) Thin-set mortar
Rationale: Thin-set mortar provides strong adhesion and durability
for heavy-duty porcelain tiles, especially on floors.
6. What is the first step in preparing a concrete floor for tile installation?
A) Applying thin-set mortar
B) Cleaning and leveling the floor
C) Installing a backer board
D) Grouting
B) Cleaning and leveling the floor
Rationale: Proper cleaning and leveling remove debris, dust, and
uneven surfaces, ensuring proper adhesion and long-term
performance.
7. Which tool is most suitable for cutting ceramic tiles in straight lines?
A) Angle grinder
B) Tile cutter (manual snap cutter)
C) Jigsaw
D) Circular saw
B) Tile cutter (manual snap cutter)
Rationale: Manual tile cutters score and snap tiles cleanly along
straight lines without generating excessive dust.
, 8. What is the recommended grout joint width for most ceramic wall tiles?
A) 1/32 inch
B) 1/8–3/16 inch
C) 1/4–3/8 inch
D) 1/2 inch
B) 1/8–3/16 inch
Rationale: Wall tiles usually have narrow grout joints, typically 1/8 to
3/16 inch, to maintain appearance and prevent excessive grout
cracking.
9. Which type of tile is highly resistant to water and frost, making it ideal
for outdoor use?
A) Ceramic wall tile
B) Porcelain tile
C) Quarry tile
D) Vinyl tile
B) Porcelain tile
Rationale: Porcelain tiles have low water absorption and high
density, making them durable in outdoor and freeze-thaw conditions.
10. What is the purpose of a notched trowel?
A) Mix mortar
B) Spread adhesive evenly
C) Cut tiles
D) Measure grout joints
B) Spread adhesive evenly
Rationale: Notched trowels ensure an even layer of adhesive with
proper ridges for full tile contact and adhesion.
11. Which method is best for leveling large-format tiles?
A) Using shims under the tile
B) Using a self-leveling mortar
C) Hammering tiles into place
D) Ignoring slight unevenness
B) Using a self-leveling mortar
Rationale: Self-leveling mortar ensures a flat, even substrate suitable
for large-format tiles, reducing lippage.
12. What is “lippage” in tile installation?
A) Uneven grout lines
B) Uneven tile edges causing a height difference
