April 15, 2014

Tech Talk – January 2014

TEC-sponsorInstalling ceramic tile, glass tile and stone in interior wet areas

Slope, weeps, and flashing are key to managing water and avoiding failures

Donato PBy Donato Pompo, CTC, CSI, CDT, MBA,
Ceramic Tile and Stone Consultants (CTaSC),
University of Ceramic Tile and Stone (UofCTS).  

Exterior decks and balconies, and interior showers and bathrooms have historically been problematic areas for the installation of ceramic tile, glass tile, stone tile and other stone products. Typically problems are due to installer error, such as not using appropriate materials for those applications, or not having clear enough specifications. In each case it is the result of not following industry standards. Exploration into the intricacies of exterior decks and balconies can be an entire article in itself, but for this story, we will focus on interior showers and bathrooms.

Industry standards are created by industry consensus groups consisting of installers, producers, and industry experts through organizations such as ANSI (American National Standards Institute), TCNA (Tile Council of North America), ASTM (America Society for Testing and Materials) or ICC (International Code Council).  These consensus group members combine their many years of experience with science to establish standards so problems and failures can be avoided and not repeated.  Thus if standards are not followed then known potential problems can’t be avoided.

As a forensic investigator for over 11 years, I have investigated many failed interior showers and bathrooms. I have found that the common denominators to tile and stone failures in these applications were the lack of proper slope, plugged weep holes, and inadequate flashing to contain or manage the water that resulted in various types of damages.

Managing water volume

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First, consider the volume of water that showers are subjected to on a daily basis. Since these areas are likely to be subjected to more water than a typical roof is subjected to annually, it is imperative that extra care and attention are spent on specifying and constructing them. This is accomplished by properly managing the water so it is controlled and safely evacuated from those areas.

Lack of adequate slope is a common problem in interior wet horizontal applications such as shower floors, shelves and seats. It is very clear in the tile and stone industry standards, as well as in the Uniform Plumbing Code (UPC), and in the IRC (International Residential Code) or IBC (International Building Code) building codes, that the slope to drain, or away from the building, should be a minimum 2% slope. That calculates to 1/4” per foot (6 mm per 305 mm). UPC says the slope to drain in a shower must be a minimum of 1/4” per foot (6 mm per 305 mm), but not more than 1/2” per foot (13 mm per 305 mm).

Not only is it important for that slope to drain to be at the surface of the tile or stone, but it is critical that the minimum 1/4” per foot (6 mm per 305 mm) slope to drain is at the surface of the waterproof membrane or drain plane. Drains come in two sections. Where the drain clamps down on the waterproof membrane below the surface of the tile assembly, there are weep holes in the drain assembly, so that any water that migrates to the waterproof membrane can then evacuate into the drain through the weep holes.

Problem #1: Improper slope to the drain

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There are  three common problems that we run into. First, the waterproof membrane is not properly sloped to the drain. In a shower this can result in the tile mortar bed staying constantly damp, which creates a musky odor in the room, or it may cause a stone or tile floor to look wet. Excessive moisture might result in the stone spalling (deteriorating) and/or staining.   Sometimes we find that the waterproof membrane is flat or even negatively sloped away from the drain, or that there are low spots on the membrane surface where water collects.

Problem #2: Plugged weep holes

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The second common problem is drains with plugged weep holes.  Industry standards state that the weep holes are to be covered with pea gravel or with a plastic weep hole protector to make sure the weep holes stay open. Often this weep hole protection is left out, and mortar is placed over the weep holes, plugging them. Thus, if the waterproof membrane is properly sloped to drain, the water cannot escape into the drain. Again, this can result in the tile mortar bed staying constantly damp, which results in the musky odor in the room, a wet-looking floor or stone spalling or staining.

The term “spalling” refers to the deterioration of the surface of a stone. It is the symptom of a stone being subjected to excessive moisture over time. Spalling is typically caused by moisture migrating from the stone’s underlying substrate up through the stone to its surface where the moisture evaporates. As the moisture travels from under the stone through the cementitious materials, and through the stone itself, the moisture picks up various minerals (salts) which dissolve in the moisture. When the moisture reaches the surface of the stone it evaporates and the minerals precipitate into a solid again.  This expansion or crystallization of the mineral, referred to as efflorescence, causes the surface of stones to deteriorate to some degree.

Whether it is a shower or an exterior deck or balcony, the waterproof membrane surface must be sloped to drain or away from the building. Shower pans or receptors are supposed to have a pre-sloped mortar bed installed over the base substrate before installing the waterproof membrane. The pre-slope needs to have a minimum slope of 1/4” per foot (6 mm per 305 mm).

Problem #3: Membrane breaches3-techtalk

That brings up the third common problem that we find in showers: waterproofing or vapor retarders that are not complete or continuous. They tend to lack flashing at transition areas. Considering the potential collateral damages a defective balcony can develop, it is important to construct it like a big shower pan. Assuming that the deck has been properly pre-sloped, the waterproof membrane must continue, or be flashed, up the wall at least 3″ (76 mm) above any thresholds to prevent water from causing any potential collateral damages. All seams, penetrations and transitions must be properly waterproofed, flashed and sealed with a sealant. These are the areas that are most vulnerable to having problems, so they need to be given the extra attention to ensure they are installed correctly. The waterproof membrane should never be penetrated, unless it is unavoidable, and then the penetration has to be properly flashed and sealed with the appropriate sealants to ensure it will never leak.

Often we find that decks are sloped to their outer edge without any type of gutter or drain. The water drains over the side of the balcony and eventually results in staining along the siding, or staining and spalling the stone if there is stone siding. The latest trend is to use trench or linear drains that work very well and can be installed at the perimeters of decks or showers.

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So how can a tile installer make sure that showers are given the attention they need to avoid failures? It is the same old answer.  Follow industry standards and manufacturers’ directions. It doesn’t matter who is at fault when there is a problem; everyone ends up paying – either in time to defend themselves, money to fix the problem or with their reputation. So it is in everyone’s best interest to make sure that tile and stone installations are done properly. (Editor note: please visit www.tileletter.com for the full text of this story, which also addresses exterior installations).

Ceramic Tile Consultant, Donato Pompo, CTC, CSI, CDT, MBA, is the founder of Ceramic Tile and Stone Consultants (CTaSC), and of the University of Ceramic Tile and Stone (UofCTS). Donato has over 35 years of varied experience in the ceramic tile and stone industry. CTaSC provides services in Forensic Investigations, Quality Control Services for products and installation methods to include writing specifications, training programs, testing, and on-site quality control inspection services. CTaSC is a professional consulting business comprised of accomplished ceramic tile consultants, stone consultants, ceramic tile and stone installers, architects, engineers, general contractors, construction scientists and other industry specialists and experts conveniently located throughout the US and Canada. You can reach Donato by visiting the company website at www.CTaSC.com, emailing [email protected] or calling 866-669-1550.

Installing ceramic tile, glass tile and stone interior wet areas

By Donato Pompo, CTC CSI CDT MBA, Ceramic Tile and Stone Consultants (CTaSC), University of Ceramic Tile and Stone (UofCTS).

(Editor note: a condensed version of this story appears in the January 2014 issue of TileLetter)

 Exterior decks and balconies, and interior showers and bathrooms have historically been problematic areas for the installation of ceramic tile, glass tile, stone tile and other stone products.   Typically problems are due to installer error, not using appropriate materials for those applications, or not having clear enough specifications.  In each case it is the result of not following industry standards.

 

Importance of industry standards

Industry standards are created by industry consensus groups consisting of installers, producers, and industry experts through organizations such as ANSI (American National Standards Institute), TCNA (Tile Council of North America), ASTM (America Society for Testing and Materials) or ICC (International Code Council).  These consensus-group members combine their many years of experience with science to establish standards so problems and failures can be avoided and not repeated.  Thus if standards are not followed then known potential problems can’t be avoided.

 

Excessive moisture:

culprit in tile and stone failures

In the last ten years or so, since the demand and use of tile and natural stone has grown so dramatically, there have been a lot more failures caused by tile and stone being subjected to excessive moisture.  Obviously tile and stone are very resistant to problems as indicated by the fact that there are tile and stone installations that are still standing and functional after thousands of years of use and exposure to various weathering conditions.

But when a number of things are done incorrectly in a tile and stone installation, particularly where water is involved, it can lead to extreme damages that can cause visually aesthetic damages and substantial collateral damages of adjacent materials, which can significantly reduce the functional life of the tile or stone application.

On the other hand, if tile and stone are installed correctly, per industry standards and product manufacturer’s directions, these products can provide trouble-free installations that can provide many years of pleasing aesthetics and successful performance that will be our legacy to future generations.

In over 11 years as a forensic investigator, I have found the common denominators to failed exterior decks and balconies, interior showers and bathrooms are the lack of proper slope, plugged weep holes, and inadequate flashing to contain or manage the water , resulting in various types of damages.

First, consider that exterior decks and balconies are often not only subjected to water directly from rain, but often water is channeled through drains and scuppers to these areas further subjecting them to higher volumes of water.  Plus these areas are often washed down regularly so they are further subjected to large volumes of water.

Consider the volume of water that showers are subjected to annually.  If one person takes a 12-minute shower each day in an average size shower with reasonable water pressure and using an appropriate shower head, the amount of water it is subjected to is equivalent to a roof being subjected to about 1,000 inches of rain water per year.  Since these areas are likely to be subjected to more water than a typical roof is subjected to annually, it is imperative that extra care and attention is spent on specifying and constructing them. This is accomplished by properly managing the water so it is controlled and safely evacuated from those areas.

 

 Be savvy about slope

Lack of adequate slope is a common problem in both exterior horizontal applications as well as interior wet horizontal applications such as shower floors, shelves and seats.  It is very clear in the tile and stone industry standards, as well as in the Uniform Plumbing Code (UPC), and in the IRC (International Residential Code) or IBC (International Building Code) building codes, that the slope to drain, or away from the building, should be a minimum 2% slope.  That calculates to 1/4″ per foot (6 mm per 305 mm).  UPC says the slope to drain in a shower must be a minimum of 1/4″ per foot (6 mm per 305 mm), but not more than 1/2″ per foot (13 mm per 305 mm).

Not only is it important for that slope to drain to be at the surface of the tile or stone, but it is critical that the minimum 1/4″ per foot (6 mm per 305 mm) slope to drain is at the surface of the waterproof membrane.

Drains come in two sections.  Where the drain clamps down on the waterproof membrane — below the surface of the tile assembly — there are weep holes in the drain assembly, so that any water that migrates to the waterproof membrane can then evacuate into the drain through the weep holes.

One of three common problems that we run into is first that the waterproof membrane is not properly sloped to the drain.  In a shower this can result in the tile mortar bed staying constantly damp, which results in the room taking on a musky odor or it may cause a stone or tile floor to look wet, and the excessive moisture might result in the stone spalling (deteriorating) and/or staining.   Sometimes we find that the waterproof membrane is flat or even negatively sloped away from the drain, or that there are low spots on the membrane surface where water collects.  These same conditions can be found on an exterior deck or balcony.  Obviously an exterior deck or interior commercial floor with multiple drains is a somewhat complex installation for the waterproof installer and the tile installer. In these cases, you will have transition areas that peak and slope in one direction or the other towards the respective drain.  So it is critical to make sure that the drains and slopes are properly laid out to allow for all the water that reaches the membrane to readily evacuate through the drain weep holes.  Even when there are drainage mats installed on top of the waterproof membranes to facilitate the evacuation of water from the mortar bed into the drain, if the waterproof membrane is not properly sloped it can result in expensive problems.