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Waterproof systems in tiled showers

Updated: Oct 25, 2023

According to the Center for Disease Control and Prevention (CDC), materials such as paint, wallpaper, insulation materials, drywall sheets, cardboard, and carpets, among others, commonly favor the growth of molds( CDC, 2021). In Utah, most of the constructions have in great quantity these materials. Therefore the probability of flourishing mold is high. Furthermore, in humid places in the house, such as the shower or the laundry room, the chances of mold growth are even higher. For this reason, it is essential to know the options to protect buildings from the existing humidity in Utah. In this article, I will discuss some of the options in the construction market and their main differences.

Water-resistance is not the same as Waterproof. Thirty years ago, there was no technology available today to protect buildings in humid areas of the house from water. Instead, builders used to install a grid-like sheet of metal over the frame in the shower and then add a layer of cement that would act as a backing to support the tile installation. Over time this construction method (grid - cement) was replaced by what we know as cement board. The sheet system cement held is mechanical to the house frame with screws, providing the necessary support for tile installation. However, over time, the cement board begins to generate leaks inside the walls when having prolonged exposure to water, damaging the house’s structure and helping with the growth of mold. So the cement board system is water-resistance but not waterproof.

Fifteen years later, builders thought that the shower floor was the place where water leaks occur. So factories developed a new waterproof system that consists of installing a plastic membrane under the mortar layer in the shower; this layer effectively works. Their job is to keep water away from the subfloor and walls of the house. The installers assumed that the water would accumulate on the floor to be taken out by drain. This idea became obsolete as the presence of steam in showers became increasingly common. As a result, water collects on the shower pan and the walls. Then it became more necessary to change the water resistance of cement board for products that would allow building waterproof showers.

Green guard waterproof
Green guard waterproof

Liquid Membranes

These membranes are made of rubber polymers and designed to withstand prolonged exposure to water but not to withstand prolonged exposure to steam. Tile installer must apply over walls with gaps up to ⅛ inch in conjunction with waterproofing and an anti-cracking band. The liquid membrane must fully cure before tile installation, and the curing process must occur between 45 and 69 degrees Fahrenheit. Generally, this process takes between 24 and 72 hours to complete depending on the manufacturer.

Like sheet membranes, they should not be used outdoors or submerged in water. In addition, they should not be applied directly to the wood and its derivatives.

In Utah, there are a wide variety of brands available in specialty and retail stores. The most used are Hydro Barrier by Laticrete, Aqua defense by Mapei, and Red guard by Custom. In my experience, I would say that Hydro Barrier is one of the best in this type of membrane.

Liquid membranes come with warranties of up to 5 years if used correctly, and their prices range from $ 0.8 to $ 1.7 per square foot.

Schuter waterproof
Schuter waterproof

Sheet membranes

The chemical composition of these membranes will change with each manufacturer. However, most of these membranes have polymers that allow their structure to be completely waterproof and vapor proof. Manufacturers recommend using this type of membrane in humid areas of the house such as showers, laundries, steam rooms, among others.

Its correct installation requires the use of modified mortar to ensure its adherence and operation. Sheet Membrane should not install on wood or its derivatives.

One of its main advantages lies in its manufacturers’ guarantee, which ranges from 25 years onwards, as long as they have been installed following the manufacturer's requirements.

One of their disadvantages is that these membranes cannot be submerged in water. Therefore their use outdoors, such as roofs or areas of high expansion and contraction of materials, is not recommended.

Sheet membranes must install it on flat surfaces that do not have gaps greater than ⅛ inch.

In Utah, these membranes can be found with relative ease, the leading brands are Kerdi which Schluter manufactures, and Hydro ban manufactured by Laticrete. They can cost between $ 2 and $ 3 per square foot.

Schluter Waterproof
Schluter Waterproof

Foam boards

This type of product is relatively new to the market, and its versatility allows it to do much more than just protect wet areas from water. Its composition allows delivering 100% protection against moisture. They are made chiefly of structural foam, polymers, and membranes of different compositions. They are installed mechanically with screws that hold the blade directly on the frame. Foam board can be cut with a knife without generating suspended dust. Joints and screw holes must be covered with anti-fracture membranes adhered to the board with modified mortar or special silicone glue during the installation. Most of this type of system has warranties from 15 years if installed according to the manufacturer's specifications.

It is difficult to think about the disadvantages of this type of system; however, during covid, it has been challenging to find these foam boards; even for many contractors, it has been a headache to get these products lately.

In Utah, you can find Kerdi board made by Schluter and Cement foam board made by Sentinel. Its cost varies between $ 1.8 and $ 3.5 per square foot, including screws and anti-fracture membranes.

Regardless of the waterproof system you choose, it is crucial to install this system correctly, following the manufacturer's instructions. An installer can generally find these instructions on manufacturers' websites with relative ease. Don't let your remodeling project be ruined by improper use of materials.

CDC, (2021, September 5). Basic Facts about Mold and Dampness.

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