How to Calculate Thin Set Mortar
Thin set mortar allows the tile installer to cement tile on a layer of adhesive less than 1/4 inch thick. A thin layer of mortar works best on horizontal surfaces that have already been patched and leveled since it's less forgiving of flaws than some thicker adhesives. Always check a manufacturer's recommended coverage guidelines since each can vary, but for calculating an estimate of how much to buy, plan on each 50-lb. bag of mortar mix covering up to 75 sq. ft. of surface area. Does this Spark an idea?
Instructions
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Measure the room or item to be mortared and record the dimensions in feet or inches.
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Calculate the surface area of the room or surface by multiplying its length times its width (A=L x W). In a room that is not a precise rectangle or square, you will need multiple area calculations, one for each rectangle or square that makes up the room. Calculate the area of a circular space by drawing a line in the center point of the area and measuring out to the edge of the circle. Multiply that measurement by 2 and then by 3.14. Add together all of the area calculations for the room to get the total area.
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Convert your area calculations to square feet. If you've measured in inches, divide your area total by 144 to convert that number into square feet.
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Divide the number of total square feet by 75 to determine how many 50-pound bags of thin set mortar will be needed for the project. Round the quotient up to the next whole number and buy that many bags.
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Tips & Warnings
If the room or surface contains many walls at a variety of angles, it may be helpful to draw a picture of it in a computer aided design program or on graph paper to help you determine the area. Calculate the area of irregularly shaped sectors of a room by rounding them out to the next larger rectangle or square.
Always mix and apply mortar according to manufacturer's instructions.
References
- "Lowe's Complete Tile and Flooring"; David Toht, 2004
