Just like Mom used to say, what matters most is on the inside. While the facade of a floor covering is important for aesthetics, underlayments that cannot be seen from the surface can mean the difference between a three- to five-year installation and a lifetime installation.

What is an Underlayment?

Underlayment products can act as many things depending on the finish flooring type. For example, an underlayment can act as a barrier between the subfloor and flooring material to provide a cushion and create space for expansion and contraction from changes in temperature, humidity and natural movements. For tile floors in bathrooms, underlayments are used to provide a flat surface for the finishes and to add support to prevent the tile and grout from cracking when walked on, as well as enough flexibility to absorb movement and expansion with changing temperature and humidity—given this space is regularly wet. 

Although many individuals in the flooring industry consider underlayments the key component of a successful installation, the benefits often remain underappreciated and undervalued. As underlayments continue to grow in popularity within the construction industry due to track records of success providing uncoupling, anti-fracture and sound reduction to tile and stone installations, product availability has increased along with product knowledge. 

Whether the installation deals with a plywood substrate, is in need of total leveling or requires waterproofing, building materials manufacturers have created underlayments to address whatever needs imaginable. The three main categories of underlayments are backer boards, surface preparation products, and membranes. 

Backer Boards

Dating back to the 1970s, backer boards revolutionized the tile industry by providing a tile-ready surface in the form of a sheet or panel. While this method is tried and true, flooring contractors must be wary of the board’s shape becoming irregular or wavy due to deficiencies that cause the surface to be unlevel, which brings us to the next category. 

Self-Leveling Underlayment

Prior to, or in place of, using a backer board, self-leveling underlayments create a flat or level floor. The key to a successful installation using a self-leveling product is preparation. If the substrate is in poor condition, whether that be not dry enough or properly cleaned before using a self-leveling underlayment, the finished flooring performance will be compromised. 

resin flooringIn addition to floor coverings like wood or tile, self-leveling underlayment is popularly covered with specialty laminates. In addition, specialty floor preparation underlayments can be used under high performance resinous floor coatings that are perfect for applications that must meet strict health code requirements, such as in a hospital. Unlike standard sheet or tile flooring that contain seams and grout lines where bacteria can become trapped, these applications are seamless. Resinous floor coatings can also be custom designed with a wide variety of solid-color, quartz and simulated terrazzo coating systems. Organizational logos or inspirational messages can also be incorporated into the flooring for an enhanced look.


The last of the three main categories of underlayments are membranes. 

Crack isolation membranes can take the form of sheet goods, liquid applied and trowel applied systems, and are designed to isolate tile and stone finishes from minor in-plane substrate cracking. Additional characteristics such as waterproofing and sound reduction properties are also offered depending on the product.

installing membraneAnother type of membrane is an uncoupling membrane. These products are typically plastic membrane systems geometrically configured to provide air space between the tile and substrate to allow independent movement between the two and limit the transfer of stresses. Uncoupling membranes can also have additional features, including a mechanism to receive floor warming cables, waterproofing or sound control. 

Before working with crack isolation and uncoupling membranes, installers need to determine the type of application needed, the type of tile or stone to be used, and whether or not the project may require any waterproofing properties, as these factors will affect which specific products can be used. 

For a quick turnaround, some types of sheet or peel and stick membranes may be preferred. With trowel-applied products, contractors can often save on labor costs as you can often apply crack isolation and a thin-set in one application. 

Trend Alerts 

As the construction industry continues to advance, so do the products available to contractors for use. 

Technical experts are increasingly working to optimize the formulas and installation methods of underlayments so that tile and flooring contractors are able to install required materials in a matter of hours instead of days, which helps reduce the developer’s overall carrying costs on the construction site. 

At Laticrete, and across the industry, we expect to see advancements with the combination of underlayment products, such as sound attenuation, waterproofing and crack isolation reduction in thickness with higher performance ratings, as well as combinations with sound attenuation, waterproofing and uncoupling with floor heat.