Frequently Asked Questions

Find answers to the most commonly asked DIY questions about tile and stone installations.


Where can I buy MAPEI products?

MAPEI products are available in the U.S. through large retailers such as Lowe’s . To find the store closest to you, click the “Find a Retailer” link at the top of the page.

How do I know how much product to buy?

We provide coverage information in many places. The back of the bag includes a chart, the Technical Data Sheet does as well, or the convenient calculators available on the Projects and Products pages will let you know how much to buy. You will need basic information such as the size of the area you are tiling, the size of the grout joint you plan to use, the thickness of the tile, and the type of trowel you will be using. More information on each of these topics is included in the product FAQs for the products you are considering.

What grout colors do you offer?

Each retailer decides the number of colors they stock, but MAPEI has a wide array of grout colors available. The Products tab can point you to our grouts and each grout includes a list of the colors available. Remember that your computer screen may not show the grout color exactly, so be sure to double-check them with the grout cards available at the store. We also have acrylic and silicone caulks that are formulated to closely match in color to finish your installation.

How do I know if I can do a project myself?

There is no simple answer to that question. Successful DIY projects typically start with research, planning, and preparation. This site will help give you the steps but it will be up to you to make sure you have the needed tools, tile, and know-how to proceed. With all of that said, many common tile and stone installations are perfect DIY projects to beautify and add value to your home. The employees at the store can help guide you and there are many online resources that answer questions, have informational videos and give the basics of tile installation. MAPEI also has a staff of former tile installers that are just a phone call away.

Where can I find a contractor near me?

If you decide that you’re not quite ready to tackle your project yourself, many tile industry organizations maintain lists of contractors. For your convenience, visit these non-MAPEI sites to find contractors near you:

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Surface Prep

When do I need to use a primer for a tiling project?

Primers promote the bond between one layer of the installation and another. Before tiling over surfaces, ideally they should be dry, able to absorb water (but not damaged by water), and rough. Extremely smooth surfaces (such as existing tile) benefit from a bond-promoting primer. Any installation of a self-leveler should start with priming. Our Project calculators have more information to help you make an informed decision about using a primer.

How can I prepare an uneven subfloor?

For small areas (think of a bird-bath-sized depression), a patch is sufficient. Larger uneven surfaces should have a self-leveler applied. The Products page includes information about both patches and levelers.

How can I prevent moisture damage to my floors?

Tile and grout aren’t waterproof. If the substrate over which you are tiling can be damaged by water and water is likely to be present, a waterproofing product should be used. Our project calculators can help you decide if one is needed and point you to the correct products.

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Mortar & Tile Adhesives

What is the difference between thin-set and mortar?

Thin-set is a specialized mortar that has been designed to be applied as a relatively thin (3/32″ or less) layer. This is in contrast to traditional installations where mortar is used much thicker (1″ or more) as a ‘mud bed.’ So, all thin-sets are mortars but not all mortars are thin-sets.

What is a ‘medium-bed’ or a ‘large-and-heavy-tile’ mortar?

Mortars designed to be used with large tiles (greater than 15″ on any side) or heavy tiles (more than 5 lbs. per square foot) used to be called medium-bed mortars because they could be used thicker than thin-sets. Because they also have other favorable properties (such as the ability to hold up heavy tiles without slumping), they have recently been renamed large-and-heavy-tile-mortars by the tile industry.

What are the benefits of a ready-to-use mortar?

As the term implies, ready-to-use mortars are ready to go right out of the bucket. They don’t require mixing with water.

When should I use a ready-to-use mortar?

Typically ready-to-use mortars work best for applications with small tiles (less than 6″ on a side) being installed on porous surfaces in areas that won’t have standing water. Because ready-to-use mortars require air to cure (unlike cement mortars), there has to be a way for air to get to them. Very large tiles, waterproofing membranes, and the presence of water can all interfere with curing. The Products page has extensive FAQs about working with mastics and ready-to-use mortars.

What trowel size should I use?

The trowel size is determined by the size of the tile being installed. Generally speaking, the smaller the tile, the smaller the trowel. Our project calculators offer more information about choosing the correct trowel. You can also get more information from our Trowel Size FAQ available when calculating coverage.

What type of adhesive should I use for glass tile?

Glass tile requires a white mortar that has been smoothed flat so that the ridges don’t show through the tile. Our project calculators can guide you to the correct mortar for your situation.

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Grouts & Caulks

What are the differences between sanded and unsanded grout?

Sanded grout is recommended for grout joints larger than 1/8″ and for most flooring applications. Because sanded grout literally contains sand, it doesn’t work well in grout joints smaller than 1/8″ or with tiles that are likely to be scratched (glass, glossy wall tiles, soft or polished stone). Our Project calculators will help guide you to the correct grout for your situation.

What is a ready-to-use grout?

Ready-to-use grouts are not based on cement chemistry and can be used right out of the bucket. MAPEI Flexcolor CQ is a ready-to-use grout, it does not require sealing and it doesn’t have color consistency problems (cement-based grouts can if too much water is used to mix or clean). These grouts eliminate many of the hassles DIYers experience with cement-based grouts. The primary installation difference is that you can start cleaning a ready-to-use grout right away instead of needing to grout a large area before cleaning.

What is an epoxy grout?

Epoxy grouts are ‘commercial-grade’ grout… literally. They are typically used in installations where stain and chemical resistance, color consistency, and durability are required. They do require a different method for cleaning and the residue can be stubborn to remove, so practice before diving in.

How do I determine the correct size for my grout lines?

While the trend today is towards smaller grout joints, grout joints do serve multiple important purposes in an installation. Tiles are not all the same size, so grout joints mask this variation. Tile also expands and shrinks so grout joints give this movement somewhere to go. As a general rule, porcelain tile requires a minimum 1/8″ grout joint and wider joints are recommended if the tile has more size variation. Rectified stone and some wall tiles can have smaller joints, but all installations need grout joints. More information on grout joints can be found in the project and products pages.

What causes grout to crack?

Movement. Tile shrinks and expands, buildings move, substrates crack from below. All of these can cause grout to crack.

Can old grout be re-grouted?

If the old grout is simply discolored, there are cleaners and colorants that can restore the look. If the grout is damaged, it must be removed a minimum of 2/3 of the depth of the grout joint before it is replaced as cement grouts won’t stick to themselves. MAPEI Flexcolor CQ will stick to itself so repairs can be made without removal.

What is that white film in my grout joints?

Most likely it is efflorescence, a salty residue that can form on cement grouts and be stubborn to remove. Efflorescence cleaners are available or a colorant may be needed.

How do I select the right caulk for my project?

Acrylic caulks tend to be easier to use and clean but aren’t the best bet for areas prone to foot traffic and standing water. Silicones are required in these applications. More information on caulks can be found on the product pages.

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Sealers & Maintenance

How often does my grout need to be resealed?

It depends on the grout and the sealer. Cement grout mixed with only water will need to be sealed more frequently than one mixed with a latex additive. Less expensive sealers require more frequent application. Check both the grout and the sealer containers for recommendations or give us a call.

How do I clean grout without damaging it?

Use neutral pH cleaners and elbow grease. Specialized cleaners are available; just make sure that you are using the correct cleaner for your type of grout.

Do you recommend pre-grout sealing?

Pre-grout sealing is recommended for very porous tiles (usually stones like travertine or marble or tiles like Saltillo) when they are being grouted with a color that is in high contrast to the predominant color of the tile.

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