As ceramic tile flooring technology has advanced to introduce large-format tiles and more intricate designs, subfloor prep has also evolved to address the needs of these new design options. To understand how changes in ceramic tiles are impacting installation training, here’s a quick overview of three key aspects of ceramic tile substrate prep along with cautions about what can happen when prep is subpar.
Leveling.
Substrate leveling is always essential, but it is especially critical for projects using large-format ceramic tiles. To avoid issues, assess the substrate and level it using a self-leveling compound or other leveling system to create a smooth, even surface. Take special care to correct any irregularities and allow adequate time for curing, as large tiles and intricate designs require a nearly flawless surface.
Note: If the substrate is not perfectly level, tiles can develop weak spots that lead to cracking, chipping or loosening over time.
Waterproofing.
Waterproofing a substrate for ceramic tile is critical, particularly in wet areas such as bathrooms, showers and kitchens. Liquid waterproofing membranes are versatile and easily cover irregular surfaces, while sheet membranes deliver a durable barrier with a consistent thickness. When using a liquid membrane, take care to apply the liquid evenly and allow sufficient drying time. For sheet membranes, follow proper overlap and adherence techniques to avoid leaks.
In both cases, make sure the membrane fully covers all surfaces where water exposure is expected, paying special attention to seams, corners and penetrations. Both membranes offer reliable performance when properly applied, so the choice often comes down to the tile manufacturer’s recommendation or the installer’s preference.
Note: If waterproofing is skipped or improperly applied, moisture can seep into the substrate through the tile system and lead to mold growth, adhesive degradation and substrate damage. Over time, this can cause complete tile failure.
Movement and expansion.
Movement joints and expansion gaps allow for natural expansion and contraction of tiles caused by temperature and moisture changes. Accounting for movement is particularly important in larger installations where temperature shifts or humidity fluctuations are more likely to impact tile stability. Ensure movement joints are sized and placed according to manufacturer guidelines and use flexible filler materials designed for movement to prevent cracking, buckling and “tenting” of the tile.
Note: Without adequate space for movement, tiles can crack or debond. Movement can also affect grout joints, leading to grout failure and water infiltration.
Leveling, waterproofing and movement techniques are not new to ceramic tile installers, but the extra attention needed during substrate prep often is. Larger tiles and intricate designs are much less forgiving when a substrate is not properly prepared, so keeping up with current best practices is essential for continued success.
With ongoing professional development and training using the latest ceramic tile products, installers can confidently tackle any tile job and deliver a beautiful, durable ceramic tile floor.
David Gross is the executive director of INSTALL. He previously served as a full-time instructor at the Northeast Carpenter’s Apprenticeship Training Fund in Hammonton, N.J., and he has also sat on the United Brotherhood of Carpenters and Joiners of America Local 251 executive board.
