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Whether your tile installations trend more toward commercial projects or residential, there’s no escaping the need to waterproof a lot of them. Showers, steam rooms, balconies, fountains -- any project that demands water be retained or guided toward drainage -- requires adequate waterproofing beneath the tile. Not doing so will likely cost the installer thousands of dollars (or more) to repair. A waterproofing failure cannot only cause bonding issues with the tile job itself; it can also destroy adjoining areas that may require complete removal and replacement. Water damage to joists, ceilings, drywall and other systems can quickly drive up that repair price tag for the installer, and that’s not even counting microbial growth issues tiling leaks will introduce.

The good news is there are numerous products on the market that provide varying levels of waterproofing protection. Sheet-applied membranes sit below or above the mud bed, depending on product specifications. Cementitious membranes are one- or two-component, polymer-modified, cement-based waterproofing materials that offer sufficient waterproofing. There are also backer board/building panels that require no additional membranes when installed properly.Each of these has its strengths and weaknesses, and some are better for certain jobs over others. Liquid-applied membranes, however, have numerous benefits over other solutions that make them one of the most instrumental and frequent products you’ll use.

What Is a Liquid-Applied Waterproofing Membrane?

According to ANSI A118.10, a waterproof membrane is a water-repelling material that is “load bearing, bonded…for thin-set ceramic tile and dimension stone installation.” Liquid-applied membranes are single- or multi-component membranes applied in liquid form, obviously. These cure to form a monolithic (i.e., seamless) membrane with superior waterproofing capabilities. Some such membranes are applied with integral reinforcing fabrics that enhance tensile strength and bring crack-bridging properties.

A waterproofing failure cannot only cause bonding issues with the tile job itself; it can also destroy adjoining areas that may require complete removal and replacement. Photos courtesy of Merkrete (Click on each image to enlarge.)

Why Choose Liquid-Applied Membranes?

Let’s start by saying they are incredibly easy to use. Liquid-applied waterproofing membranes can be applied with a brush, roller, trowel or airless sprayer. Also, because of the way they are applied, liquid-applied membranes eliminate extra cost at corners. Inside and outside corners can simply be cut from the fabric. Additionally, liquid-applied membranes are ideal for installations requiring waterproofing irregular shapes. Plus, its thin section does not interfere with elevations at the installation site.

Liquid-applied waterproofing membranes like Merkrete’s Hydro Guard SP-1 are also low VOC for a safer installation. Its antimicrobial formula abates mold and mildew growth to which wet areas are highly susceptible, and its fluid nature generates less waste and makes it very easy to apply for reduced labor and installation time.

How Do I Put Down a Liquid-Applied Waterproofing Membrane?

As mentioned before, these membranes are flexible in that they can be applied with a paintbrush, tight-nap paint roller, small V-notch trowel or airless sprayer. Most products allow all methods but be sure to consult the manufacturer’s instructions before choosing your tool.

As always, be sure your substrate is prepared and ready to accept the liquid-applied waterproofing membrane. Pre-fill all substrate voids, cracks and cold and control joints. When ready, you will typically apply your first coat at change-of-plane areas and embedding fabric, if required. From there, move to the field of application, coating everywhere tile will be installed.Follow the manufacturer’s specified mil. thickness.

If applying Hydro Guard SP-1, lay down Merkrete’s Reinforcing Fabric Type 2 while your first coat is still wet. Once dry, apply your second coat of membrane perpendicular to the direction of your first. The Reinforcing Fabric Type 2 will be “sandwiched” between the two coats, lending amplified strength and stability to the waterproofing application. When the liquid-applied membrane has cured for the manufacturer’s prescribed period -- four to six hours for Hydro Guard SP-1 -- flood testing may commence.

Are Liquid-Applied Membranes the “Flagship” of the Waterproofing Fleet?

Well, that’s one way to phrase it. Simply put, there are many fine waterproofing solutions on the market today. However, experience has proven that liquid-applied membranes provide so many benefits over the others that, if you have not already done so, warrant giving them a closer look. From their long-lasting reliability to their installer-friendly properties, liquid-applied membranes should be the go-to system for tile waterproofing needs.