CTI CTI Substrate Preparation & Assessment

Question 1

What is the maximum allowable deflection for a subfloor that will receive ceramic tile, according to the Tile Council of North America (TCNA) guidelines?

Accepted Answer

L/360

Answer

L/180

Answer

L/720

Answer

L/240

Question 2

Which moisture testing method measures the amount of moisture vapor emitting from a concrete slab using a sealed hood over a defined area?

Accepted Answer

Calcium chloride test

Answer

Relative humidity probe test

Answer

Plastic sheet test

Answer

Moisture meter test

Question 3

What is the maximum acceptable moisture vapor emission rate (MVER) for a concrete substrate before installing tile with a standard latex-modified thinset mortar?

Accepted Answer

8 lbs/1,000 sq ft/24 hrs

Answer

3 lbs/1,000 sq ft/24 hrs

Answer

5 lbs/1,000 sq ft/24 hrs

Answer

10 lbs/1,000 sq ft/24 hrs

Question 4

A CTI inspector finds a wood subfloor with a gap of 1/4 inch between plywood panels. What is the correct assessment?

Accepted Answer

Unacceptable — gaps must not exceed 1/8 inch

Answer

Acceptable — gaps allow for wood expansion

Answer

Acceptable if panels are tongue-and-groove

Answer

Unacceptable — no gaps are permitted at any time

Question 5

When assessing an existing concrete slab for tile installation, which condition would require the inspector to recommend surface preparation before tiling?

Accepted Answer

A surface that is dusty or has a laitance layer

Answer

A surface that has cured for more than 28 days

Answer

A surface that tests at 65% relative humidity

Answer

A surface that is perfectly level and flat

Question 6

What is the minimum thickness of a single layer of plywood used as a subfloor for ceramic tile installation over joists spaced 16 inches on center?

Accepted Answer

3/4 inch (19 mm)

Answer

1/2 inch (12.7 mm)

Answer

5/8 inch (15.9 mm)

Answer

7/8 inch (22.2 mm)