CFI Tile & Stone Installation 2 — Questions and Answers
Question 1: What is the minimum recommended grout joint width for rectified porcelain tiles?
- 1/16 inch (Correct answer)
- 3/16 inch
- 1/4 inch
- 3/8 inch
Correct answer: 1/16 inch
Rectified tiles have precise, uniform edges allowing grout joints as narrow as 1/16 inch.
Question 2: When installing large-format tiles (24"x24" or larger), which trowel method is recommended to ensure full mortar coverage?
- Spot bonding
- Back-buttering only
- Mortar on substrate only
- Back-buttering combined with substrate troweling (Correct answer)
Correct answer: Back-buttering combined with substrate troweling
Large-format tiles require both back-buttering and substrate troweling to achieve the required 95% mortar contact.
Question 3: What does ANSI A108.02 specify as the minimum bond coat coverage for tile installed in wet areas?
- 65%
- 80%
- 95% (Correct answer)
- 100%
Correct answer: 95%
ANSI A108.02 requires 95% mortar coverage for tiles in wet areas, exterior applications, and for large-format tiles.
Question 4: Which type of membrane is most appropriate for waterproofing a shower floor prior to tile installation?
- 15-lb felt paper
- Foam backer board alone
- Uncoupling membrane without waterproofing layer
- Fabric-reinforced liquid-applied waterproof membrane (Correct answer)
Correct answer: Fabric-reinforced liquid-applied waterproof membrane
Fabric-reinforced liquid-applied membranes create a continuous waterproof barrier that fully bonds to the substrate.
Question 5: What is the purpose of a cleavage membrane (like 15-lb felt) installed beneath a mortar bed?
- To add waterproofing to the assembly
- To allow the mortar bed to float independently of the substrate (Correct answer)
- To improve bond strength of the mortar
- To prevent alkali migration from concrete
Correct answer: To allow the mortar bed to float independently of the substrate
A cleavage membrane allows the mortar bed to move independently, preventing cracks in the substrate from telegraphing through.
Question 6: When using epoxy grout, what is the most critical installation condition to monitor?
- Substrate pH level
- Ambient temperature and humidity (Correct answer)
- Grout joint width
- Tile absorption rate
Correct answer: Ambient temperature and humidity
Epoxy grout has a limited working time that shortens significantly in high heat, making temperature and humidity control critical.
Question 7: What is the industry-standard maximum lippage allowed between adjacent tiles in a standard residential floor installation?
- 1/32 inch
- 1/16 inch (Correct answer)
- 1/8 inch
- 3/16 inch
Correct answer: 1/16 inch
ANSI A108.02 specifies a maximum lippage of 1/16 inch plus the allowable variation in the tile itself for floor installations.
CFI Tile & Stone Installation 2
What is the minimum recommended grout joint width for rectified porcelain tiles?