10 Most Common Waterproofing Mistakes

Experts estimate that roughly half of the showers in America are leaking. That could mean water coming through the ceiling in a second story shower, or water puddling for years instead of draining causing an ideal environment for mold and mildew to grow. A typical shower receives over 1000 inches of water per person per year. This dwarfs the amount of rainfall per year in the wettest state in America. Even your roof sees far less water than your shower, and yet regulations for a roof are far more stringent than for showers. Tile and stone are amongst the most sustainable and luxurious building materials available. They offer a green, sanitary, and durable way of adding beauty to your home. Their lifespan of approximately 50 years adds appeal as well. In spite of all the benefits they have to offer, some still consider tile and stone to be the wrong choice. The truth is most issues that arise from using tile and stone can be avoided by having the knowledge to properly waterproof the space. Waterproofing is essential to the functionality and longevity of a shower area. Without proper waterproofing, small mistakes can have severe consequences and result in expensive repairs. We are going to list 10 common waterproofing mistakes that almost always lead to failures or issues. If you’ve experienced any of these issues, please reach out to us by phone or email so we can give a free inspection.

1: Inappropriate Tile and Stone Selections for Wet Areas

More often than not, homeowners or contractors will select tile and stones that have a good aesthetic. Stones such as sandstone, travertine, or limestone provide a unique look but tend to be very porous. Porous stones need frequent maintenance such as cleaning and sealing, and still risk the chance of staining. Today’s technology has made it possible for porcelain tile to look like most stones, giving the option to keep the aesthetic without the extra maintenance. Glass tile has also become more popular and while it can be beautiful, it is often improperly installed.

2. Believing Tile, Grout & Sealer Are Waterproof

It is a common misconception that tile and grout are waterproof. Not only are they not waterproof, they’re highly susceptible to water vapor and steam. Water runs through cementitious grout like a sieve. Although porcelain is non-porous, most stone surfaces are going to be very porous. It’s important that the substrate is thoroughly waterproofed without a single compromise. The tile and grout are essentially a pretty veneer. If the waterproofing is not done 100% correctly, the tile and grout will not stop a failure from occurring. If you see a shower being prepared with cement board and only the seams of the board have waterproofing membrane, that is absolutely a failure waiting to happen. Another common misconception is that sealing the tile and grout makes it waterproof. The most common sealer used on tile and grout is called a “pentrating sealer” (also known as impregnator sealer, or clear sealer). This will repel water from the surface for only a few days, which is not it’s intended use. This happens because many of these sealers are oil based and the residual oil on the surface repels water. The main use of these sealers are to SLOW the process of staining, they do not waterproof and they do not make anything stain-proof.

3. Assuming Hardibacker or Cement Board Are Waterproof

This is a common misconception that can be disastrous. Many big box stores notoriously have a piece of hardibacker submerged in water on display to show that hardibacker is impervious to water. While this is technically true, that does not mean it is waterproof. Hardibacker soaks up water like a sponge and when used in a shower without waterproofing, you will have loads of water vapor and sometimes even liquid water soaking through and into the framing behind the board. Even if a water-impervious wall board is used on your shower, it will likely still need an additional waterproofing membrane applied to the surface before any tile is installed. Some high density foam boards are the exception to this rule. (As a side note, hardibacker has terrible bonding capabilities compared to most other options on the market so it’s just a good rule of thumb to leave that material for siding and do not let anybody put it in your shower!)

4. Not Recognizing the Potential for Efflorescence to Occur in Wet Environments

Efflorescence occurs when soluble salts in the mortar rise with moisture through the grout joints to the surface and deposit a white, or yellowish, residue. This residue can be difficult to remove and may even require use of a sulfamic or phosphoric acid. Efflorescence is a natural occurrence with any portland cement-based product, and the best way to control and prevent it is to manage the moisture. In the case of showers done in the traditional mortar-bed system, the addition of a drainage mat on the shower pan liner reduce or even eliminate efflorescence altogether.

5. Improperly Prepared Waterproofing Membrane

The industry standard for load-bearing, bonded waterproof membranes for thin-set ceramic tile and dimension stone installation is ANSI A118.10. There are three types of membranes that fall under this standard:

• trowel-applied

• peel-and-stick

• sheet-applied

The trowel applied membrane is mistakenly considered to be the easiest to install. It requires a manufacturer-specified thickness that can be measured by a film thickness gauge. Often, to achieve the required thickness, more than one coat is required, and in some cases, a reinforcement fabric is needed, especially for inside corners. Keeping the thickness consistent and within the standard can also be difficult. Insufficient coverage does not necessarily result in actual leaks until the area exposed to moisture becomes saturated. This could take days, weeks, or months, but once it starts to leak, there can be water infiltration behind the walls that results in a lot more damage than initially meets the eye. Peel-and-stick and sheet-applied membranes are often more expensive, but have the advantage of being manufactured in the factory to the correct thickness. This reduces the chances for installer error. A disadvantage, however, is when dealing with radiuses and other irregular shapes, in which case a trowel-applied membrane is certainly easier to apply.

6. Creating Penetrations Through the Waterproofing Membrane

Causes of penetrations and punctures in waterproofing membranes can be as simple as nailing a piece of backerboard through the membrane on a curb, or using nails or screws as spacers to stack tile on a shower wall. Penetrations through the waterproofing layer should be avoided at all costs, especially on horizontal surfaces where water can easily collect.

7. Using Wood In A Shower To Make A Curb Or Bench

2x4 lumber often warps when it dries out, even if pressure-treated and waterproofed with a liquid or sheet-applied membrane. out. The warping and twisting can compromise the waterproofing and/or the tile installed directly on top. We now have prefabricated Styrofoam, expanded polystyrene foam (XPS) and extruded polystyrene (EPS) components for curbs, benches, and other structural elements that, when waterproofed, are dimensionally stable and solid. While using wood does not guarantee installations will fail, it has properties that make it much more likely.

8. A Lack of Coverage When Installing Tile

Tiles installed in wet areas should have 95% coverage minimum. We make sure to apply 100% coverage. The tile typically needs to be back-buttered, meaning a thin coat of mortar is applied to the tile’s back with the flat side of the trowel. When there is insufficient coverage, the tile or stone often displays some shading and since the voids collect water, the chances for efflorescence increases. There is also a much greater risk of tiles delaminating, which represents a major failure and added cost for many projects.

9. Creating Little or No-Slope Drains, or Negative Slope Drains

When using a traditional mortar bed, there is a shower pan liner that needs to have a pre-slope of approximately two percent. This pre-slope is critical to ensure subsurface moisture can actively work its way to the two-stage drain used in this assembly. Additionally, weep holes must be kept open so moisture can evacuate from the area. This can be done easily by using a sub-surface drainage mat on the waterproofed pre-slope that provides rapid water drainage to the lower section of the two-stage drain. Another solution to consider is to use a topical waterproofing membrane in combination with a drain that has an integrated bonding flange. This eliminates the need for a pre-slope since the waterproofing is on top of the substrate. This assembly also reduces the overall height of the floor, and makes it easier to manage transitions at doorways and fixtures.

10. Failure To Do A Proper Flood Test

It is extremely important to check that the shower can actually hold water. Once your waterproofing is installed you will need to install a stopper to the drain and puttying-preventing any water from draining. You will then need to fill up the shower a few inches below the curb and mark the water line. It’s best to leave the water in the shower overnight. If the water has not moved below your mark you know the shower is properly waterproofed and there are no leaks. This simple test can bring peace of mind and prevent a major disaster from occurring.

Moisture management is extremely beneficial to the sustainability and workmanship of any shower build you do. It will always be much easier to prevent water damage and mold than to repair it after the fact. If you need help with an improperly waterproofed area please call us at (346)-573-2816 or email us at carley@platowtile.com.