CTI CTI Substrate Preparation & Assessment 2

Question 1

Which ASTM standard governs the in-situ relative humidity testing of concrete slabs using embedded probes?

Accepted Answer

ASTM F2170

Answer

ASTM F2170 covers the standard test method for determining relative humidity in concrete floor slabs using in-situ probes.

Question 2

A CTI inspector is evaluating an existing terrazzo floor as a substrate for new tile. What is the primary concern?

Accepted Answer

Terrazzo surfaces are often too smooth for mortar bond without surface preparation

Answer

Existing terrazzo is typically dense and smooth, requiring mechanical scarification or shot-blasting to create a bondable surface profile before tile installation.

Question 3

What does the term 'flatness' refer to when assessing a substrate for tile installation?

Accepted Answer

The absence of high and low spots over a defined measurement length

Answer

Flatness refers to the planarity of a surface — ANSI A108.02 requires floors to be flat within 1/8 inch in 10 feet and 1/16 inch in 2 feet.

Question 4

When inspecting a radiant heat slab, what additional substrate consideration is critical before tile installation?

Accepted Answer

The radiant system must be cycled (run then cool) before tiling to release residual moisture

Answer

Radiant heat slabs should be operational prior to tile installation to drive out residual moisture and allow the slab to stabilize before moisture testing.

Question 5

What is the required compressive strength of a concrete substrate before tile can be installed per ANSI A108 standards?

Accepted Answer

2,500 psi minimum

Answer

ANSI A108 requires a minimum concrete compressive strength of 2,500 psi for tile substrates to ensure adequate structural integrity.

CTI - Certified Tile Inspector Practice Test

CTI - Certified Tile Inspector Practice Test

CTI CTI Substrate Preparation & Assessment 2