CTI Waterproofing & Moisture Management Flashcards

What does the term 'cold joint' refer to in a mortar bed installation?

Answer: A seam where fresh mortar meets previously cured mortar, creating a potential weak point

A cold joint occurs when new mortar is applied against already-cured mortar, resulting in a bond plane that can crack or allow water infiltration.

Why is it critical to install a vapor retarder on the warm side of a wall in cold climates before tiling?

Answer: To stop warm interior moisture from migrating into the wall cavity and condensing

Without a vapor retarder, warm humid interior air moves through the wall and condenses on cold surfaces inside the wall cavity, leading to mold and structural damage.

What is the minimum thickness of a dry-pack mortar bed for a shower floor?

Answer: 1-1/4 inches

TCNA specification F111 requires a minimum mortar bed thickness of 1-1/4 inches for a shower floor to provide adequate strength and slope.

Which ANSI standard governs the installation of ceramic tile in the United States?

Answer: ANSI A108/A118/A136

The ANSI A108/A118/A136 series covers installation methods, materials, and performance requirements for ceramic tile in the US.

What is efflorescence, and what commonly causes it in tile installations?

Answer: White salt deposits on the tile or grout surface caused by soluble salts migrating through with evaporating water

Efflorescence appears as white powdery deposits when water moves through the mortar or grout, carrying dissolved salts to the surface where they crystallize as the water evaporates.

Which installation method provides the best waterproofing performance for a steam shower?

Answer: A continuous bonded waterproof membrane applied over foam backer board, sealed at all seams and penetrations

Steam showers require the most robust waterproofing because pressurized steam penetrates gaps that liquid water does not; a continuous bonded membrane on foam board with sealed penetrations provides this level of protection.