When ceramic tile walls or floors are the choice, many times the consumer falsely assumes that because tile was selected, it provides a waterproofing function when used as floor or wall covering. The results of this assumption can be detrimental.

Walk-in showers are an increasingly popular option for both aesthetics and an aging population. Achieving the proper pitch and providing adequate waterproofing can be challenging. There are numerous products out there that will meet the needs of this particular type of installation. Photo courtesy of Schluter Systems.


Nailing through sheet type liners does not make for a very waterproof shower seat. Topically applied sheets and liquids make this popular type of shower feature an easy installation. Photo courtesy of Merkrete Systems.

When ceramic tile walls or floors are the choice, many times the consumer falsely assumes that because tile was selected, it provides a waterproofing function when used as floor or wall covering. This is a very common misperception and often not addressed during the sales or installation process. The results of this unspoken assumption is sometimes realized only after substantial damage has occurred to the customer’s structure - possibly months, but more often, years later.

To add insult to injury, the warranty on the work has expired and in many cases of water damage and resulting mold issues, there is no insurance coverage. The cost must be borne entirely by the unfortunate consumer. In the space that we have available, I would like us to look at some of the more prominent areas of waterproofing facts and fantasies.

Along with the misconception that ceramic tile in some way affords protection from water damage, people are also convinced that what little risk of water damage they have will be further reduced by use of a sealer. Ceramic tile is an inert product and unaffected by water in and of itself. Glazed tile is typically, but not always, impervious to water on the exposed tile surface. However, this protection does not extend beyond the exposed surface. In the case of wall tile, used extensively for tubs and showers, the absorption of the tile body can be as great as 20%. The grout used in installations is often cement based. Grout is also unaffected by water as a product, however, good cement-based grouts can have an absorption rate of 7 to 15%. This is the same type of cement used in concrete roads that stays wet hours after a rainfall.

The typical uneducated answer to the absorbent tile and/or grout is it would be waterproof if we used a sealer. Sealers bring nothing to the party when it comes to waterproofing. They slow the penetration of moisture and the accompanying soils, that’s it. Sealers are more of a cleaning aid than anything else. Manufacturers will tell you they allow response time for cleaning by blocking rapid absorption. While some have amazing performance capabilities, they are not waterproofing products. Others will say that using an epoxy grout to waterproof would solve the whole moisture problem. Although there is no doubt that epoxy grout would substantially alter and nearly eliminate the absorption, it does not constitute waterproofing. All it would take is a pinhole or small spec of exposed tile edge to render it ineffective. Waterproofing is a performance requirement that can only be achieved using specific products designed for that purpose.

Complete waterproofing of any shower area is always a good choice. Stopping the water and moisture vapor at the wall surface should be an important consideration with today’s tighter building envelopes. Photo courtesy of Noble Co.

When to use and not use waterproofing products

There are few areas where waterproofing, especially those providing some crack suppression, that would not be beneficial, such as damp concrete basements, which brings us to another popular misconception. Tile related membranes are made to keep water from passing through into the structure, not keep water in the structure from passing up through the floor. They are designed to stop water at the top, not the bottom. In the case of adhesive-applied membranes, failure is a good possibility when installed over excessively damp or wet slabs. If you must waterproof a slab with vapor or moisture issues, then your options are limited but there are some breathable or vapor tolerant membranes available.

One excellent place to use basement waterproofing is in showers. This question comes up often; all shower floors should be waterproofed, including those on a basement slab. Unless waterproofed all the shower water and its accompanying organic materials will migrate through the slab into the surrounding area making for a very damp and possibly odorous basement.

Tile is becoming increasingly popular for decks, be they slab on grade (not a huge concern other than proper pitch), raised wood decks (a big concern) or roof decks (a huge concern). The requirements for above-grade decks are very exacting and space does not allow us to explore them in depth. These types of projects should utilize only the very best products and those highly skilled in their use. Decks and patios are fraught with obstacles to a successful installation. Most typical failures occur due to unskilled or semi-skilled labor, use of inappropriate products, railing penetrations, failure to allow for thermal and moisture movement, lack of counter flashing, and poor drainage provisions. Claims for water damage in these types of installations can be for a staggering amount of money in some cases. Exterior deck, patio, and pool deck failures have provided a substantial portion of my income so far this year as a consultant. I also have yet to see a product failure, however, it was alleged there was a failing product on every job. So far all have been inappropriate product selection and/or poor workmanship. Tile can easily be used in these applications offering problem-free performance with the right selections and labor.

Unfortunately, there is no end in sight to leaky decks, tubs, showers, and an increasing amount of steam rooms. These calls seem to be increasing in number - a fact supported by every single manufacturer I have spoken with. This is really sad because it hurts the market for ceramic tile, stone, and related products. Manufacturers have done an outstanding job of developing products to address waterproofing in particular. With the blurring of the traditional tile setter into the realm of floor coverer, waterproofing has seen a disproportionate amount of failures.

It is generally accepted and well known that a floor layer can get into big trouble in this specialized area without proper training but with the current economy, many continue to try. Many retailers have just given up any thought of doing projects requiring waterproofing, even tubs and showers due to their unpleasant past experiences. If I were a distributor or retailer I would make sure my sales and installation labor was trained in the facts and fantasies of waterproofing. The opportunities available for those skilled in this highly sensitive area of installation are substantial. Don’t be afraid, learn and earn!