Keeping Wet Projects Dry

FIRST THINGS FIRST
  The initial step in avoiding problems is to understand what constitutes a wet area. The Tile Council of North America (TCNA) defines wet areas as tile surfaces that are soaked, saturated, or regularly and frequently subjected to moisture or liquids – places such as showers, tub enclosures, laundry areas, saunas, steam rooms, swimming pools, hot tubs and exterior areas.
  Also, take precautionary measures to help minimize problems. For example, consider the substrate involved, the types of joints encountered, and whether dissimilar materials are part of the mix, such as tile that abuts a metal floor drain. The Marble Institute of America (MIA) is a good source for guidelines, as are manufacturer’s instructions for waterproofing membrane products.
  Aside from special circumstances, waterproofing isn’t overly challenging. But that’s not to say things can’t go wrong. They can.
 
PROBLEM: MOVEMENT
  If a waterproofing application fails, it’s often the result of a damaged waterproofing layer. In all likelihood, substrate movement created a tear or hole in the waterproofing membrane.
  Areas of movement include substrate joints, field seams, inside and outside corners and anywhere vertical surfaces meet horizontal surfaces. When faced with potential substrate movement, there are two simple rules: Follow building codes and go by the manufacturer’s instructions for the product.
  Keep in mind that building codes supercede manufacturer’s recommendations. As an example, a manufacturer might indicate that a moisture barrier isn’t needed with a backerboard installation. However, if a building code says it’s required, it’s best to follow the building code, which dictates whether the project passes inspection or not.
  When it comes to manufacturer’s instructions, don’t deviate. A prime example is a liquid roll-on waterproofing membrane. If instructions call for mesh, use the mesh recommend by the manufacturer. The good news is that some liquid waterproofing membranes only call for mesh with changes in plane (flashing), or substrate joints, rather than the whole job. Less mesh means fewer steps, which speeds installation.
 
PROBLEM: JOINTS
  Related to movement, this potential obstacle includes control joints, expansion joints, isolation joints, and construction joints. When working with concrete substrates, pay close attention to joints within the slab, and how the waterproofing membrane is designed to work with the joint.
  As an example, installation of a waterproofing membrane with crack-isolation properties over a control joint might simply require the joint to be clean and free of debris. It may or may not require the use of mesh.
  However, using the same product for some other joints might dictate the need to install compressible backer rod into the joint with a suitable flexible sealant for movement. Consult the TCNA handbook, Movement Joint Design Essentials EJ171-05, for more details.
  Given the broad range and types of joints used with concrete substrates, the best bet is to carefully check the waterproofing membrane manufacturer’s installation instructions to verify proper waterproofing performance of the membrane. Installers will also find the MIA’s Dimension Stone Design Manual full of stone design and construction facts and details.
  
PROBLEM: EXTERIOR INSTALLATIONS
  Interior installations are one thing, but exterior projects, such as roof or balcony decks, can present real challenges. Outside, there are demanding environmental conditions – and the fact that forces acting on the stone or tile can be much greater than a comparable installation inside.
  There are a host of factors to consider when waterproofing an exterior stone surface, but chief among them is proper water drainage. An exterior installation requires the proper slope to drain water from the system before it gets a chance to absorb into either the tile, or the layers beneath the tile and above the waterproofing membrane.
  Equally important is the suitability of the waterproofing membrane for exterior use. It’s advisable to refer to local building codes for moisture vapor-transmission requirements. Another worthwhile step is to consult with the product manufacturer directly because these applications are often highly product-specific.
 
PROBLEM: SUBSTRATES
  Successful waterproofing starts with a suitable and/or properly prepared substrate. An unsuitable or improperly prepared substrate often results in an insufficient bond with the membrane. Suitable substrates will vary depending on the waterproofing membrane used. Appropriate substrates for roll-on waterproofing membranes typically include:
  • concrete, cured mortar beds and masonry;
  • gypsum wallboard and cementituous backer units;
  • APA Grade Trademarked Exposure I plywood;
  • existing ceramic tile, VCT or non-cushioned sheetgoods, provided they are single-layer and well bonded to a substrate approved for tile; and
  • adhesive residue (except tacky or pressure-sensitive adhesive).
  Regardless of the substrate, application surfaces need to be properly prepared. The substrate should be free from contamination, such as oil, grease, dust and paint. New concrete must also have the required finish and be properly cured. Surface protrusions also need to be removed, and holes and voids patched. The bottom line is that waterproofing membranes are only as good as the substrates under them.
 
PROBLEM: METHODOLOGY
  Operator error is always a viable suspect when problems arise with waterproofing installations, or any other stone installation for that matter. If problems do occur and the source is traced to methodology, it’s because the installer failed to follow manufacturer’s installation instructions or industry standards. Common instructions for a roll-on membrane include:
  • pre-filling concrete cracks;
  • treating cracks greater than 1/8” wide as expansion joints;
  • applying liquid membranes to the proper thickness;
  • installing a continuous membrane without voids; and
  • allowing for proper curing time.
  Always follow manufacturer’s instructions and industry standards.
 
PROBLEM: PRODUCT SELECTION
  There is a wide variety of waterproofing membranes on the market. The goal is to install a system that prevents water from migrating from the surface of the stone to the substrate, where it could cause problems. Architects will typically specify the use of a waterproofing membrane, yet installers need to also rely on their own expertise when determining what product is best for the job.
  When in doubt, check the standards issued by the American National Standards Institute (ANSI). The voluntary standard governing waterproofing membranes is ANSI A118.10; the standard is the best way to determine whether a waterproofing membrane meets clearly defined performance guidelines. A waterproofing membrane’s label or datasheet should also outline which ANSI standards are being met; if none are mentioned, consider an alternate product.
  Choosing a system also dictates the need to analyze other factors associated with the project, such as ease-of-use, curing time, etc. Some one-part liquid formulations require no mixing, while others use two or more components mixed on the job.
   Likewise, some ready-to-use formulations dictate that the substrate be primed, while others do not. Some systems also require multiple steps and others require fewer steps, which ultimately impacts the profitability of the job.
  Also consider whether the waterproofing membrane can be used on freshly placed (or green) concrete, which can be an advantage on fast-track projects.
  Finally, carefully think through other product features, such as mold and mildew protection, which ranks high on the list of end-user (homeowner) concerns.  At a minimum, determine whether the product meets ANSI requirements.
  For a higher level of assurance, determine whether the membrane is tested against appropriate mold and mildew test methods. The most stringent test method known is “ASTM D5590-00 Standard Test Method for Determining the Resistance of Paint Films and Related Coatings for Fungal Defacement by Accelerated Four-Week Agar Plate Assay.”
 
TRIAL BY WATER
  The importance of a water test following the completion of a waterproofing application can’t be overstated. Doing so provides the opportunity to correct a problem before the stone or marble is installed.
  The test simply involves filling the wet area with water, after the membrane is installed and properly cured, to check for leaks. Some waterproofing membranes allow the test to be conducted within 48 hours after the membrane is installed; some require a 72-hour waiting period. Whatever the case, don’t skip the water test.
  Attention to detail and planning ahead, combined with a heads-up approach to potential problems, will make the next waterproofing installation go smoothly. It also helps to ensure your customers’ installations stay high and dry for years to come.

This article first appeared in the September 2006 print edition of Stone Business. ©2006 Western Business Media Inc.