From the Floor Up

Getting the Facts Straight about Underlayment

Posted by Daltile Team on Aug 13, 2015 8:30:00 PM

Acacia Valley in Ark 9 x 36 planks.

Before you can even start thinking about putting down that beautiful tile, you have to make sure your surface is properly prepared. So how’s your underlayment?

What is Underlayment?

Underlayment is one or more surfaces under your tile that give it an added layer of protection. It is a key element of your flooring system and will help you achieve a better finished floor.

There are lots of different types of underlayment. Some are specifically built to reduce sound. Others help warm the floor. Some are liquid or spreadable, others are solid sheets. Whatever their specialties, their primary function is to provide better stability and a level, even surface for your thin-set mortar before you set the tile.

How is Underlayment Used?

Think of your floor almost like a sandwich. With the sub-floor on the bottom and the tile on top, you select materials—the underlayment--to create a floor that meets your needs. If you want a floor that resists moisture, reduces sound, and has crack suppression, your floor “sandwich” might have three or four layers of materials that prep your floor to do all those things. On the other hand, if you want a basic underlayment, you may opt for just a leveling underlayment that creates the flat, level surface required for tile.

The most common type of leveling underlayment is cement-based and it comes in many forms including everything from backer board to spreadable mortars. Most popular are the self-leveling versions that resemble wet cement. They do require troweling and usually sanding to remove trowel grooves. It dries in about two to 24 hours but can require more or less time depending on the temperature, humidity, and thickness.

What Underlayment Do You Recommend?

By far, Daltile’s most popular underlayment material is Dal-CIM 500 EX. It’s extra easy to install due to its semi-ridgid design and split-release backing. It’s extra lightweight—at 42 pounds per roll (compared to 80 pounds per roll). And extra sustainable, which means it’s made with recycled, regional, and low VOC materials for earth-friendly construction.

Dal-CIM 500 EX combines two of your flooring requirements into one because it is a sound-reduction membrane and a crack-isolation material all in one. Use it with the Dal-CIM 500 Primer and an optional installation kit.


Your contractor can help you make the right choices about your subfloor and underlayment. When it’s done right, you can breathe easy that your tile floor will look great and last a long time.

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Topics: How to Install Tile

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