Wondering what is causing me to get on my soapbox? In my new job as an independent technical consultant I am getting out a lot more and have had an increased opportunity to see firsthand the results of both inferior work and resulting damage caused by lack of proper moisture management. Decks seem to fare even more poorly than showers. In the space allotted this issue both cannot be addressed so we will devote this issues topic to showers and address decks at a later date. Traditional mortar showers are becoming extremely rare as time alloted for the job and skill of the workforce decline. Those who have such skills are in high demand even in today’s tight market. Not a job on every block mind you, or even every subdivision, but they are out there. My highly paid mudslinging union brothers still have not missed a day of work, though they could easily get some time off if so desired. The typical mud shower can last 50 years or more, many are well over a 100. Most old mud showers I have removed had lead pans that were leaking. Most commonly, right at the clamping ring because even then, as today, you rarely find the code required pre-pitched shower pan. When constructing a full mud shower the materials cost is very low. A few bags of cement, some sand, and little wire lath, and you’re set to go. Older homes also had a lot of drafts and air moved freely within the wall which is a fast way to dry things when they become damp or wet and keep them that way. How many have felt the wind from a drafty outlet in an older home? While mud still reigns as king when it comes to flat and true surfaces, an argument could be made that with the reduced or in some instances total lack of breathing ability more common in today’s energy efficient structures, due consideration should be given to moisture management even in full mortar shower applications.
Both the need to manage moisture in energy efficient homes and a desire to make the best use of the available labor skills are the drive behind many of the more recently developed products. From a structure perspective, building codes require higher more energy efficient structures. Many are employing exterior membrane systems and other energy efficient construction practices all aimed at lower heating and cooling cost and thus preserving natural resources with the tighter building envelope. We no longer have the luxury of frequent air exchanges within the structure. As showers occupy a small place in the home little attention has been paid to the increased amounts of moisture exposure retained in the residence. Many falsely assume that use of a backer board that is waterproof solves the moisture problem. There is a difference between being waterproof and offering waterproofing. The majority of popular backer boards offer no waterproofing properties whatsoever. Some are actually quite good at absorbing water. Many require use of a vapor retarder on the studs to protect the wall cavity from excessive moisture. Some offer reduced vapor transmission and moisture penetration and still others actually do have waterproofing properties when properly installed. Very few offer the properties of a vapor barrier which is defined under Building Code as having a Perm rating of 1 or less. For steam showers waterproof does not constitute vapor proof. One is a molecule, the other is a gas. The simplest analogy I have come up with is a kitchen drain. It is without question waterproof as water passes freely with no leaks. How would you feel about using that same pipe to hold your natural gas or propane? Anyone with common sense knows the answer to that question.
Given the tighter building envelope the shower floor should not be immune from consideration either. We constantly hear from homeowners, building industry professionals, and even insurance companies who feel their floor has sprung a leak because of poor grouting, cracked or missing caulk, and no application of sealer. As a matter of fact, while putting this article together I had a call from a university project manager who was absolutely confident the reason the newly constructed gang shower in the dormitory was leaking into the kitchen below was due to lack of a sealer application. As most of us realize, he has a much bigger problem than no sealer. Mortar shower floors provide a drainage system for showers when properly constructed. When improperly constructed they provide a septic reservoir covered by a thin clay surfacing material. Even when properly constructed they can emit substantial amounts of moisture. When using current building practices of tight homes with low fresh air flow, a case could be made that any home would benefit from less humidity by reducing the moisture vapor arising from the floor as well as the walls.
There are many “non- traditional” products on the market that can serve as aids in moisture management in varying degrees. We have a plethora of waterproofing products, both new and old. Some come in liquids, others come in sheets, all with different application and performance attributes. In my personal opinion some of the most promising products come to us as foam wall panels and premade shower bases. When I first saw foam products being used in showers some years ago I was highly skeptical of their value and saw it as the continuing demise of the tile industry. Now with many more years’ exposure to tile and foam products coupled with intimate knowledge of their performance abilities, I have come a full 360 degrees and view them as part of future moisture management in shower systems. I certainly don’t think they will completely replace traditional methods but they are true problem solvers when it comes to coupling reduced building time, available skills, and moisture management. I think building officials are coming to the realization that though small in size showers can make a substantial contribution to the humidity level in a home with restricted air movement. A study a few years back by one of my distinguished colleagues, Don Halverson and long-time contractor Ceil Hunt, determined that the average shower stall, dependent on size and water flow receives the equivalent of between 1,000 and 2,000 inches of rain per year! That is 100 times greater than most roofs receive regardless of what state you live it. Unlike the roof, it does not all roll off. The design of the shower system will determine how much moisture will be retained. Tight building envelopes, over 1,000 inches of rain; that is a scenario that begs for good moisture management.
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