CTI CTI Substrate Preparation & Waterproofing

Question 1

What is the maximum allowable floor deflection for a substrate intended for tile installation per TCNA guidelines?

Accepted Answer

L/360

Answer

TCNA specifies the substrate must not deflect more than L/360 of the span under live load for tile installations.

Question 2

Which moisture test measures vapor emission rate in pounds per 1,000 sq ft per 24 hours on a concrete slab?

Accepted Answer

Calcium chloride test

Answer

The calcium chloride test (ASTM F1869) measures vapor emission rate in pounds per 1,000 sq ft per 24 hours.

Question 3

What is the maximum acceptable moisture content for a wood subfloor before tile installation?

Accepted Answer

19%

Answer

Wood subfloors should have a moisture content of 19% or less to prevent warping or bond failure beneath tile.

Question 4

Which type of waterproofing membrane is applied as a liquid and cures to form a seamless, continuous layer?

Accepted Answer

Bonded (liquid-applied) waterproofing membrane

Answer

Bonded liquid-applied waterproofing membranes are brushed or rolled on and cure to form a seamless, continuous barrier with no seams.

Question 5

What is the primary purpose of a cleavage membrane in a mortar bed installation?

Accepted Answer

Allow the mortar bed to float independently of the substrate

Answer

A cleavage membrane (such as 15 lb felt or 4-mil polyethylene) separates the mortar bed from the substrate, allowing independent movement.

CTI - Certified Tile Inspector Practice Test