
Many manufacturers of liquid waterproofing products offer reinforcement materials for all corners and for drains in shower applications. Almost universally pre-treatment of those areas are required for effective waterproofing.
New home construction has slowed down substantially in most parts of the United States. With it has gone some of the easy money many have enjoyed for years by just doing floor work. But, a good number of installers have continued to enjoy a healthy backlog of jobs just waiting for their talents. Why do some seem so busy and others are starving? In many instances, it is their higher skill level and ability to do jobs beyond the ordinary floor or backsplash installation. True today as it always has been since I been in the trade, a good floor tile installer does not make a good shower installer. Retailers seem to have a hard time grasping this concept. They assume because the installers work always looks great on the floor he certainly could do the same with a shower or tub. Installers know better, many cringe at the idea of having to enter such a foreign realm with the very high stakes liability that water damage in someone’s home brings. Floor and wall tile installation require a certain amount of skill and some very basic knowledge. Showers and wet areas on the other hand require a high degree of both skill and knowledge, more so when mortar shower bases are used. This is typically where things can go bad for a good floor installer. With the proliferation of products being offered today, it can go from bad to worse particularly in the area of product knowledge on installation requirements. There are many fine and viable products being offered but often there is little information readily (keyword) available other than the typical sales pitch. Showers being constructed today are increasingly complex and with them the inherent risk of water damage increases. While this can easily turn into a book, let’s take a short look at some of the basics in shower building 101.

Building a curb properly out of mortar is a time consuming task. Pouring a curb of concrete provides waterproofing issues. Nailing backer board into the curb makes for leaks and requires additional waterproofing. Manufacturers have come up with numerous products to make curb building simple; some are displayed here.

Common floor drains are not impossible to fit with an effective seal at the drain where surface waterproofing is required but are very difficult and require exacting methods with 0 margin of error. Showers installed over on-grade concrete floor drains should be waterproofed.
Once we have provided for the proper drainage we need to select the appropriate waterproofing material. There is a proliferation of waterproofing products on the market today. Years ago we used lead and cooper sheets. These sheets were then seamed together with molten metal. History has taught us that when properly done those systems can provide many years of service. There is one draw back however, the days of those systems are numbered by the interaction of the wet mortar to the metal which causes metal degradation to failure at a rate dependant on both pitch of the installation and the installation itself. In some areas of the country there is a system called hot mop. This is a highly regionalized method using hot tar and roofing felt in multiple layers. Then we have the next generation of materials which are sheets of either a PVC or CPE product. These come in varying widths and typically with accessory items such as pre made inside and/or outside corners, adhesives for seaming, and sealants for use where penetrations are present. It is always preferable to use as large a sheet as reasonably possible. Why make a seam and assume any risk if not necessary? If you’re local supplier does not carry a complete line of products with all these items it would be wise to consider special ordering the materials you most commonly use and stocking them yourself. We found this to be the case especially with the larger 6’ sheets and outside corners in our particular area.

Traditionally a layer of tar paper, some metal lath, and mortar are used to pre-pitch a shower pan. This is simple and inexpensive but unless there is additional work in the house you have to wait till the next day to install the shower pan material. There are several pre-made products on the market that allow work to continue.

Shower drains for mortar applications require a specific type of drain to allow for water to pass through the floor mortar and down the drainpipe. This drainage is provided by small weep holes at the lower part of the drain.
The best idea and typically a requirement when using any direct bond waterproofing application is to treat the entire shower to prevent any water that may be absorbed by the wall backing surface. More often than we care to see, we receive pictures of showers that have had partial waterproofing or inadequate film thickness and have failed. With few exceptions, backer boards are not waterproof. Those that are still have special requirements for fasteners and edges to effect true waterproofing. Because many backer boards do allow either water or vapor to pass,mostrecommend the use of a vapor membrane behind their panel in tub and shower applications but may be omitted when the entire unit is waterproofed. Building codes vary on this requirement and always prevail over manufacturer recommendations. In the case of showers where no surface waterproofing is present, a vapor membrane should extend a minimum of two inches over the top of a conventional shower pan liner system.
While we have spent a great deal of time on the floor getting the water from the walls and floor down the drain and preventing damage that will otherwise occur, we should pay due attention to other areas of the shower. When most plumbing codes were written, and government bodies being what they are, no consideration was given to seats, niches, and knee walls. Curbs also remain an item of mystery for many. All of these surfaces must have a pitch to direct the water to the floor drain. They must all be waterproofed as well. The new TCA Handbook for 2007 has added language to reflect this need and perhaps some day code will also reflect this issue more appropriately. The failures of seats in particular are rampant.

There is currently only one drain made for direct bonding of waterproofing materials in showers and it is part of a proprietary system. It is placed in the top of the mortar bed. Others can be adapted but each manufacturer has their own preferences and instructions for effectively sealing the shower drain. There is no universal or industry method, each is manufacturer specific.
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