CTI CTI Waterproofing & Moisture Management

Question 1

According to TCNA guidelines, which areas in a residential shower MUST have a waterproofing membrane?

Accepted Answer

The entire shower floor and walls to at least 3 inches above the highest water point

Answer

TCNA requires waterproofing on all shower walls to at least 3 inches above the highest water source to prevent moisture intrusion behind the tile.

Question 2

What is the purpose of a pre-slope under a shower mortar bed?

Accepted Answer

To direct water toward the drain and prevent pooling beneath the tile

Answer

The pre-slope creates a sloped mortar layer beneath the liner so water that penetrates the tile system drains to the weep holes rather than pooling.

Question 3

What minimum slope is required on a shower floor for proper drainage according to TCNA standards?

Accepted Answer

1/4" per foot

Answer

TCNA recommends a minimum slope of 1/4" per foot toward the drain to ensure standing water does not accumulate on the shower floor.

Question 4

Which type of waterproofing membrane is applied as a liquid and then becomes a continuous flexible sheet when cured?

Accepted Answer

Liquid-applied topical membrane

Answer

Liquid-applied membranes are brushed or rolled on and cure to a seamless waterproof sheet that conforms to any shape.

Question 5

What is the function of weep holes in a clamping-ring shower drain?

Accepted Answer

To allow moisture trapped between the liner and mortar bed to drain out

Answer

Weep holes sit at the level of the liner and allow any water that seeps through the tile system to escape into the drain instead of pooling beneath the mortar bed.

(CTI) Certified Tile Installer Practice Test

(CTI) Certified Tile Installer Practice Test

CTI CTI Waterproofing & Moisture Management