Q&A / 

How to Work With Thinset Mortar

Thinset on Concrete
Thinset on Concrete

Many houses on Long Island have ceramic tile that was installed by master craftsmen decades ago using a cement mortar that’s 100-percent waterproof. Guess what? You can still use a similar cement-based mortar to install your tile and it’s not that hard to do.

When you decide to use these thinset mortars to install wall or floor tile, the biggest benefit is the tile will bond permanently to the floor or the wall if you just do a few simple things.

You can access a handy quick start guide with more tips and a full tool list here: opens in a new windowThinset Quick Start Guide

Degree of Difficulty: hammer-2-5

Step One: Purchase the correct thinset, white or gray, and the proper trowel to apply the mortar. White thinset is used with white or very light-colored stone or tile. It’s a good idea to use this if you’re using white grout between the finished tiles. The notched trowel you use is dependent upon the overall size of the tile you’re installing. Look on the bags of mortar for the recommended trowel size.

Step Two: Read the instructions on the bag of thinset mortar and follow them to the letter. Be sure the surface you’re applying the thinset to is clean, dust-free and in very good condition. If applying to a floor, consider using a crack-isolation membrane. These membranes help to prevent cracks in the finished tile.

Step Three: Only mix as much thinset mortar as you can cover with tile in about 15-20  minutes for the best results. NEVER add more water to thinset that’s getting hard in the bucket. The thinset mortar should have a consistency of warm cake icing.

Step Four: Dust and dirt can cause thinset to bond poorly. Wipe surfaces with a damp sponge to remove dust and dirt just before applying the thinset. The damp surface also helps to increase the bond, especially in hot, dry weather.

Step Five: When setting tile into the thinset mortar, it’s important the entire tile contacts the fresh mortar. Hollow spots under tile are to be avoided as are humps in the floor. Tile laid in this fashion will crack.

Step Six: Working with thinset on floors is very hard on your knees. Wear high-quality kneepads or kneel on a very soft rubber gardening or similar cushion.

Step Seven: As you install tile, avoid excess thinset from squeezing up in between tiles. If this happens, it’s a sign you could be applying too much thinset using the wrong notched trowel. The thinset will get in the way of grout you’ll apply later.

Step Eight: Pay close attention to the time you’re supposed to allow the thinset to cure and harden. Often you must stay off the new tile floor 48 hours before starting to grout the floor. This cure time will be longer if the temperature of the room is below 60 F.

Summary: Be sure you read all instructions, including safety instructions when working with thinset mortar. It’s a product that can cause skin irritation. Wash off all thinset from your skin and from any tile surface. If allowed to dry and cure, it can be nearly impossible to remove the thinset.

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