The membrane must be pitched to drain water prior to the installation of the mortar bed. This is one of several pre-made units which allow for less down time in shower construction. The mortar fill is to extend the pitch to the edges of the shower.


This is a technique used in making a completely waterproof installation where wire lath is fashioned into a basket and placed over the membrane. The wire will be anchored by the mortar on the inside of the shower and fasteners on the outside.
Installing tile in a wet area? No? Are you sure? Just what is a wet area? The official answer as contained in the Tile Council of America Handbook says, "Tile surfaces that are either soaked, saturated, or regularly and frequently subjected to moisture or liquids (usually water), such as gang showers, tub enclosures, showers, laundries, saunas, steam rooms, swimming pools, hot tubs, and exterior areas."

Yes, tub enclosures are considered wet areas but then again so are laundry rooms under this definition. What about bathrooms, kitchens, decks, porches and the like? The applicable sentence is the first one in the paragraph. Seems like only common sense to most experienced tile persons. But, calls and emails indicate it is not quite as well known as one would assume. Then there are consumer perceptions, one very common one, that when one installs ceramic tile over a surface it is waterproof. This incorrect assumption even prevails among some general contractors and homebuilders. Hundreds of millions of dollars in damages to structures will occur this year due to either lack of knowledge or poor installation practices and procedures. Many times that dollar amount is currently in the making, the damage being shielded by the structure itself. This is obviously not limited to ceramic tile installations, nor does it take into account the monetary damage and suffering incurred by our friends in Florida, who months later are still trying to regain a sense of normalcy.

Let me share some of the more recent events I have experienced related to this subject. Recently we had a homeowner attend one of our installation courses. I know what you're thinking and no, sad to say, it is not unusual, quite more common than one would think as was her reason. Her motivation was desire for knowledge to prevent future financial losses. Seems she had hired the most knowledgeable contractor known in her area to work on her home. There was no quibble on price; just do it, and do it right. After several years a half wall in the master bath shower, which supported a large glass panel separating the shower from the tub deck, had begun to grow mold. This is a very popular floor plan in many homes today. It would appear that the contractor failed to waterproof the wall supporting the glass panel across from the showerhead and rather than having the water repelled from the supporting structure, it was absorbed by it. By the end of the week here she was so incensed by the misinformation she had been give numerous times, she wrote an article on it; here is an excerpt from it about her shower:

For my house, water is the enemy. The mold in my shower is not from poor housekeeping. It is from a leak that is causing damp wood or other food sources for mold to grow. Water is demanding and cannot be ignored. There are proper waterproof methods of installing tile showers and tubs. The Handbook explains all. Unfortunately, I am a victim of someone's lack of training.

Strong words, but she paid dearly for the lack of knowledge exhibited by their contractor. By the way, when contacted, his response was as always, I have been doing this 30 years and never had a problem. I could spend the rest of this article telling stories about that specific type of installation alone, one resulting in a successful class action lawsuit by a homeowners association for five million dollars, but we will move on.

Any time a surface has potential to be exposed to anything other than minimal incidental amounts of water, it should be considered a wet area. Wet areas require waterproofing to protect the object or structure. As an example, a couple has several young children and a whole bucket of bathtub toys are noticed on your arrival to give an estimate for a new ceramic floor. This floor deserves of something other than just a traditional backer board in the case of a wooden structure or even in a slab on grade application. Water will assuredly migrate through the grout, backer board, or concrete substrate into the adjoining framing members. In the lawsuit mentioned above, all slab on grade substrates, the exterior and interior walls were severely damaged by water intrusion caused by poor design, and resulted in replacement of those walls in hundreds of homes.

These pre-made curb units solve the problem of not placing fasteners in the curb and add speed to the shower installation; they are well worth the expense.

As a note of interest, the first complaints were received 6 to 7 years after construction, and 10 years prior to the filing of the lawsuit. The builder's defense? Homeowners had failed to maintain the grout with annual sealing and periodic replacement of caulk. First, grout sealers will not serve as waterproofing by any stretch of the imagination. Secondly, caulk should have never been used in wet application, showers slab on grade with no waterproofing, in this case. A sealant should always be used, which is a different product, and has different chemistry. You must also consider if this is nuisance water, such as the occasional splash with kids in the tub or if this is an area that requires complete waterproofing, to protect against overflowing tubs or toilets. Both have different requirements. For a splash of water, the substrate may be all that needs waterproofing. For flood protection, the toilet and tub would require a sealant and the waterproofing material would need to extend to the maximum possible height that could be achieved by the volume of water available. After that, the water has to go somewhere, preferably not into the hallway. Laundry rooms are especially critical. Any room can be a challenge in maintaining both aesthetics and function when it comes to draining water.

The leaky and/or moldy shower problem continues to be very prevalent; no shortage of failures there, unfortunately. It remains the number one failure in wet applications by a wide margin over all others, even after factoring the commonality of the installation. Lack of positive drainage or pre-pitch under the shower pan contributes to breakdown of the mortar and fosters mold growth. Failure to provide drainage at the weep holes located on the lower part of the drain body creates a similar condition. Management of wall cavity moisture, a long-term problem, is often lacking. Many backer board manufacturers recommend a vapor membrane on the studs behind the panel. It amazes me that some feel this is an unneeded step in protecting the wall cavity. Given the removal of liability coverage resulting from mold lawsuits by many insurance carriers, this is not a step where I would second-guess wiser minds, those that engineer and manufacture the product.

A shower drain consists of two drains actually, the sub drain for the mortar bed at the bottom and the top where the water will drain from the floor.

Another very problematic area in showers is proper location of the backerboard and application of grout and sealants. With a few cement board exceptions, backerboard should not be sitting on the shower floor in any application. To do so causes the water to wick up the wall, which will cause failure in some products. Grout should never be used between the wall and the floor for several reasons one being expected movement differential between the floor and wall, the other being the grout will also wick the water up the wall. Other common issues; nails in the top and inside of the curb, not bringing the membrane above the curb to protect the doorjambs or bringing it down over the front of the curb. This is all written in most plumbing codes but with very little enforcement.

Years ago, our options were very limited when it came to waterproofing ceramic showers. Proliferation of failures have affected confidence by consumers in ceramic showers and caused a decline in this type of installation. This is something very evident from calls and emails received and is due entirely to lack of knowledge or fear of mortar showers and waterproofing. Today we have products available that make waterproofing the top surface of the shower, under the tile, not the supporting substrate an effective means of preventing water damage. Handicap showers in particular benefit from topically applied waterproofing. Clearance and proper drainage is always a concern. I would consider nothing less than waterproofing the entire floor and providing wall protection as well in these applications. Running the membrane 2 feet beyond a curbless shower, as is a common practice in handicapped showers, is ineffective and doomed to failure. It is not hard to envision that surface applied waterproofing may someday become code in all wet applications, eliminating potential hidden leaks or lack of waterproofing. Then again not to be cynical, but it makes too much sense, so who knows.

Applications where protection of surfaces from water damage are numerous as are the products that can provide protection, but are they all equal? No, they are not. There are many limitations to various products.

The subdrain must be kept open for water to drain out of the mortar bed. This can be accomplished by using pea gravel, broken tile, spacers, or a pre-made protector.
Some provide intermittent protection, some provide constant protection, and some, but not all, provide for submerged application. We recently had a learning experience in a waterproofing class on the critical application of fabric reinforcing when using a roll-on membrane system. Modern day products are highly engineered and while they may offer ease of application, they are unforgiving of failure to follow instructions. If you have an unusual application every manufacturer would be more than willing to discuss the critical installation areas. I would also strongly suggest that whenever you do use a manufactures waterproofing system you use the complete system. I had a call yesterday about using one manufacturer's roll-on membrane and another's thinset. Previous experience with this particular issue allowed me to tell the contractor with fair certainty he would have to remove and reinstall the 900 square feet of porcelain tile, thinset and waterproofing due to a chemical incompatibility between the two products, He was extremely irritated that manufacturer A didn't work with B and they hadn't bothered to tell him. Mixing installation systems and products is asking for disaster given the highly engineered products used today.

Let's close this with a little discussion on setting materials in wet applications. I have been working on a thinset article for sometime now gathering information and doing a few tests here and there. Every time I think I am close, a new product or technology comes out. For more than a thousand years we had sand and cement to install tile. For roughly 55 years we have had thinset mortar. For 45 years we have had liquid latex. Polymers (dry latex pre-mixed in the bag with sand and cement) have been around for maybe 35 years now. Their performance properties are constantly evolving and improving. While not in everyone's literature, most manufactures have 25 to 30 different types available. The possibilities are endless in this regard. You can formulate a thinset to do virtually anything but put itself on the floor; however, I did get introduced to a pourable thinset recently; Iguess that's close. This all sounds wonderful; life is good, there is a product for virtually any need including setting tile under water at the bottom of a swimming pool; yes, it is true. BUT it is very unwise to assume that all thinsets are unaffected by water, many are. As chemistry increases the abilities to bond tile to many surfaces, many thinsets are affected by exposure to water during the curing process and beyond. The perception is sand, cement, what can happen? The reality is that with sand, cement, and dry polymers, lots of things can happen. The old school of if there are no lumps in the bag it will be fine to use no longer universally applies. Some modified thinsets have no water resistance at all and can go bad without a single lump in the bag. All manufacturers have preferences for dry, intermittent, and submerged exposure. It would be very wise to consult with your favorite supplier on which to use where, I think you may be surprised. I am going to be nice and not talk about mastic because this is an article about wet areas, and mastic doesn't belong in wet areas. I will say I ordered some every month, 10 pails to go with my 20,000 pounds of thinset. Real tile persons don't use mastic in wet areas. However, I would like to thank those that do for their financial contribution to my retirement fund.