Reference Library : Videos : How to Install CUSTOM Polymer-Modified Mortars

How to Install CUSTOM Polymer-Modified Mortars

Video Transcript

The second step to a successful tile installation is selecting the right mortar and installing it correctly. This creates a strong bond between the tile and the surface. We are going to show you how to use a cementitious mortar, such as one of the mortars shown on screen. The mortar you need is determined by several variables.

Consider the size of the tile, the type of tile and the location where it will be installed. For regular size porcelain or ceramic tile under 15 inches on all sides, select one the mortars listed. Large format tile, including plank-shaped tile, is any tile with one or more sides longer than 15 inches. For these projects, or for any natural stone, you need a specialized mortar that has been formulated for setting large or heavy tile.

Glass tile is unique and difficult to bond. It calls for a specialized product with a brilliant white color that enhances the look of glass. For time-critical installations, choose a quick curing mortar that allows grouting in as little as two hours. Use a white mortar when installing light colored tile or grout. Darker tiles and grout can be installed with a gray mortar.

Most tile is installed in areas that may need surface preparation before tiling. This can include leveling, waterproofing or crack isolation treatments. CUSTOM’s cement backerboards, membranes, mats and leveling products can help protect the tile installation and contribute to a lifetime warranty. 
Depending on your project, assemble the following tools and materials:
• 5 gallon bucket
• Electric drill with box-beater mixing paddle
• Clean water
• Large measuring cup
• Trowel
• Grout spacers
• Measuring tape
• Straight edge or level
• Tile cutter
• Knee pads
• Dust mask and
• Impervious gloves, such as nitrile

The size of the trowel used to apply mortar will depend on the size of the tile. Use a larger notch trowel with large format tile, and small notch with smaller size tile. See the size chart of the back of our mortar packages. Review our Technical Data Sheets for additional details and coverage charts to help plan your project.

Next are the steps for installation. First, sweep and clean the surface to remove dust and contaminants. Put on impervious gloves, such a nitrile. Then, measure and pour cool water into a five gallon bucket. The amount of water needed is shown on the back of the mortar package. To ensure accurate water levels, we recommend mixing the entire 50 pound bag of mortar. Mix for 5 minutes, either by hand or with an electric drill and a mixing paddle. Wear a dust mask while mixing the powder.
After mixing, allow the mortar to slake or stand for 5-10 minutes. Then remix it, but do NOT add more water. Once mixed, you will typically have about 45 minutes to apply the mortar before it becomes too stiff to work. Apply a thin skim coat of mortar to the floor or wall with the flat side of the trowel. Add additional mortar and comb it in straight lines, holding the trowel at a 45-degree angle. This will ensure ridges are the correct height to support the tile. Make sure that all trowel ridges are running in a single direction, parallel to the shortest side of the tile. Next, add a back butter coat to the back of any large format tile, or tile that is installed on walls or outdoors.

Finally, set the tile firmly into the mortar. Move it back and forth across the ridges, but not side to side. This collapses the ridges and prevents air from getting trapped beneath the tile. Make sure each tile is level with those around it. Also, periodically lift a tile to confirm you are getting at least 80% mortar coverage to the back of the tile. Any stone, exterior tile or tile set in wet areas requires 95% mortar coverage. This is very important to prevent cracks in the tile and to eliminate hollow spots. Clean any excess mortar from the tiles and grout joints. Leave a quarter inch gap at perimeters and changes of plane.

These will be filled with a flexible sealant or caulk after you’ve grouted the tile. Be sure to follow the instructions on the mortar package. Typically, mortar must cure for 24 hours before you begin grouting.

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