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

Only the shower floor

Answer

Only the lower 6 inches of walls

Answer

Only behind the tile on the back wall

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

To provide decorative texture

Answer

To increase the floor height

Answer

To add structural support

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

1/16" per foot

Answer

1/2" per foot

Answer

1" per foot

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

CPE (chlorinated polyethylene) liner

Answer

PVC sheet membrane

Answer

Foam backer board

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

To increase water flow speed

Answer

To prevent clogs

Answer

To anchor the drain to the liner

Question 6

Why should a PVC or CPE shower liner never be installed on top of a cured mortar bed without a slip sheet?

Accepted Answer

Sharp mortar particles can puncture the liner during installation or from foot traffic over time

Answer

It would prevent drainage

Answer

It would prevent bonding of the top mortar layer

Answer

It would cause efflorescence