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Top 5 Top Tips for Controlling Moisture Vapor Emission in Wet Tiled Areas

Video Transcript

Here are our Top Five Tips for controlling moisture in wet environments. 

Tip #1

Install a Waterproofing Membrane with Low Permeability

Wet tiled areas subject to routine levels of high humidity require a low perm vapor barrier as moisture passing through the tile assembly can be just as damaging as water over time. This is even more important in a continuous use facility like a spa or health club.

When the waterproofing membrane will also be used as a vapor barrier, TCNA recommends that the membrane have a water vapor permeance rating of 0.5 perms or less. This is tested per ASTM E96 Procedure E. 

The procedure E method addresses the amount of water vapor transmission in high temperatures to simulate these environments.  Any project with the potential for high humidity and moisture vapor will benefit from using a low perm waterproofing membrane. 

Third-party testing has confirmed that CUSTOM’s RedGard Crack Prevention and Waterproofing Membrane is the first on the market to exceed these requirements with a perm rating of .36. 

Liquid-applied RedGard Membrane conforms to all of the substrate surfaces and provides a continuous vapor barrier up to all penetrations. For best results, apply RedGard to the surface of a cement backerboard such as WonderBoard Lite and use an alkali resistant mesh tape to continue the membrane in changes of plane.   For the floor areas, RedGard is IAPMO approved for use as a shower pan liner so the entire area will be monolithically protected.

Tip #2: Select a Tile and Mortar that can withstand High Temperatures and Moisture Vapor

Not all tile and stones are appropriate for areas exposed to moisture vapor and humidity or very high temperatures. Be sure to install a tile that is recommended by the manufacturer as appropriate for this environment and meets ANSI standards. 

To adhere the tile or stone, choose a deformable or flexible mortar that meets ANSI A118.15 standards for high performance like MegaLite Crack Prevention Mortar. MegaLite is a non-sag mortar with ultimate performance in bond strength for demanding installations, such as setting large or heavy tile on walls and ceilings. It’s also very flexible to handle the thermal changes that will affect the installation. 

Tip #3 – Choose the Correct Joint Filler

In steam showers, the TCNA handbook allows a choice of either cementitous or epoxy grout that meets ANSI standards as a joint filler.  Both types have specific advantages and limitations. For example, cement grouts cure faster to allow quicker initial usage but in the long run, they require more sealing and cleaning maintenance. 

CUSTOM’s Prism Color Consistent Grout is a high performance grout that cures quickly and can be used on joints as small as 1/16-inch.  The use of Aqua Mix Sealer’s Choice Gold will help maintain a cement based grout.

Epoxy grout, such as CEG-Lite, is stain & chemically resistant, but must be very thoroughly cured before the steam shower can be safely used. Note that due to the high compressive and bond strengths of epoxy, some glass tile manufacturers only recommend cement grouts.

Joints that are designed to move must be filled with a suitable sealant. This includes special slip joints at wall-ceiling intersections and all changes of plane and penetrations. CUSTOM Commercial 100% Solids Silicone Caulk meets the ASTM C920 & C1248 designations for these applications.

Tip #4 – Plan Carefully to Manage Condensation and Drainage

Local and national codes govern projects that will be exposed to water vapor.  Make sure to adhere to them and the appropriate methods in the TCNA handbook, especially when it comes to insulation placement, drainage and sloping. A shower pan waterproofing membrane meeting the requirements of ANSI A118.10 and IAMPO is mandatory. 

Of course, steam shower and gang shower floors must be correctly sloped, with at least a ¼” per foot pitch to a properly constructed drain. 

To prevent condensation from dripping on occupants, steam rooms or showers also require a significantly sloped ceiling.  Per TCNA detail SR614 the ceiling must slope a minimum 2 inches per foot, which can run from the front to back or from the center of the room to the walls.

Moisture control is especially important at commercial sites that experience constant use.

#5: Ensure the Owner understands that Proper Maintenance is Required!

Facilities with steam rooms and saunas sometimes include an indoor pool, soaking tub or spa.  These submerged tile assemblies will need some special care. 

The requirements for waterproofing, mortar and grout are similar to those for steam exposure. The thin-set mortar needs to meet the ANSI requirements of A118.15, tile must meet A137.1, and if you are setting glass tile in the pool, it must meet A137.2.  Install an efflorescence-free grout like Prism, and be sure to choose a grout color that will remain stable in treated water.

Unlike plaster, tile installation materials must be fully cured in pools before they are filled. Then, the water should only be added at a rate of 2 feet in a 24-hour period to prevent shock to the tile that can cause cracking. Draining the pool for maintenance must also be gradual.

For the life of the pool, balanced water chemistry is critical in these areas!  Soft water will pull calcium and strength from the mortar and grout, so it is important the project owner knows to maintain the hardness level, which is the calcium content of the water, at 250-400 ppm.  The water’s pH must be maintained between 7.2 and 7.8.

Whether the project is a spa or shower, the issue of local hard or soft water and its effect on the grout needs to be considered, as the high heat will increase mineral deposits.

Air circulation will be an issue throughout the lifetime of the tile assembly. Make sure that adequate venting is included in the design. 

The challenge of installing tile in wet environments calls for careful planning and preparation - and the right system of tile installation products.  When you use a complete system of eligible CUSTOM products, the project can qualify for up to a lifetime system warranty. 

If you'd like to know more about controlling water and moisture, or how CUSTOM products can help you with your next project, please visit our website——or give us a call. And be sure to “like” our video, share it and subscribe for the latest tips on tile installation.

Thanks again for joining us at Custom Technical University. See you at our next edition of CUSTOM's Top 5 Tips!


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