Using waterproofing membranes for stone installations

Arthur Mintie, Director, Technical Services LATICRETE International, Inc
Arthur Mintie, Director, Technical Services LATICRETE International, Inc

More and more stone installations are being applied in wet areas. These areas include showers, tubs, spas, steam rooms, fountains and pools. These are generally considered constant wet areas and by building code and design specification, a waterproofing membrane must be used to protect spaces below and adjacent to the stone installation.

The Tile Council of North America’s Handbook for Ceramic Tile Installations provide many details that depict the use of waterproofing membrane in an array of installation methods, including walls, floors, decks, tubs, showers and pools for ceramic tile application. Many of the same principles and methods apply to stone installations.

In addition, to the constant wet area applications, a waterproofing membrane can also be used in intermittent wet area applications. For instance, the floor areas outside of a tub or shower are great candidates for waterproofing membranes. In many cases, water spills or splashes out onto these area. Left untreated, the water can migrate through the stone and grout and affect the substrate and the spaces below. Even minor water damage can prove to be very costly to repair.

Many of the membranes available today serve a dual purpose; providing both waterproofing and anti-fracture protection. The anti-fracture function helps to reduce the potential for hairline shrinkage and spider web cracks from telegraphing through to the stone surface. An excellent use area for these dual functioning membranes is electric radiant flooring warming systems and hydronic floor heating systems.

The membrane not only protects the spaces below and around the stone installation and the heating system, but it also helps to reduce the effects of thermal cycling that these types of installations can experience. The cyclying of the heating system can create thermal stresses in the setting system. The thermal stresses can cause small hairline cracks to transmit up through the stone finish. The use of dual purpose waterproofing and anti- fracture membrane can help to protect the stone finish.

Other areas that can also be waterproofed include, tub decks and surrounds, shower walls and ceilings, countertops, kitchens, exterior facades, building and home entry areas and mud rooms to just mention a few.

It has been proven that the use of waterproofing membranes within stone installations significantly reduces the potential for mold and mildew in wet areas. Some of today’s waterproofing membranes come equipped with anti-microbial protection and help to fight the effects of stain causing mold and mildew.

Waterproofing membranes also help to keep homes and buildings healthy. They help to prevent the occurrence of poor indoor air quality by protecting against the effects of water damage, including rot, deterioration of building materials, mold and mildew. A few select waterproofing membranes are certified by 3rd party independent agencies for compliance with strict volatile organic compound (VOC) guidelines. These membranes really help keep the building and home environment healthy!

Generally, waterproofing membranes for the stone and tile industry fall into three categories:

1.  Liquid Latex Rubber Applied Type

2.  Sheet Type

3.  Reinforced Latex Fortified Portland Cement Type

Within these categories are many membranes; which are thin and load bearing, adding no appreciable thickness to the installation and are fully compatible with latex fortified portland cement based thin set and medium bed mortars.

In order to apply the waterproofing membrane, the appropriate substrates should be properly prepared in a similar manner as if a direct bond latex fortified portland cement thin set mortar were to be applied.

In conclusion, stone can be successfully installed in wet area applications both for interior and even in demanding exterior applications. The use of waterproofing membranes makes sense in many stone applications. The investment that is made in selecting and installing these systems requires that consideration be given to this important installation feature. The added cost to include a waterproofing membrane in the stone installation is minute when compared to the potential repair or replacement costs that may arise from water and moisture damage.  The use of waterproofing membranes provides great peace of mind to both the installer and the building owner.

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