The following compilation is based on my experience as an expert witness and consultant on a variety of tile installation failures. Although there are substantial differences between residential, commercial, and industrial projects, the reasons that some tile installations fail cut across all categories and encompass both DIY and professional installations.
#1 StupidityThe # 1 reason why tile installations fail is stupidity. The market is filled with excellent materials that are accompanied by clear instructions, and the Tile Council of America-for over 50 years-has published methods of installation that achieve the desired results. Unfortunately, designers, contractors, installers, and architects with an indifference towards quality do not read instructions, guidelines, recommendations, warnings, cautions, or limitations, and often use materials that were never designed nor tested for use with ceramic tile. Don't do any tilework, or provide framing or slabs for tilework unless you have a TCA Handbook. If you are installing tiles professionally, you need to have an updated copy of the ANSI A108 American National Standard Specifications for the Installation of Ceramic Tile, as well as application and installation literature for every material you use to install tile. If you do not follow these minimum standards and the manufacturers' instructions, you are probably cheating your customer, as well as endangering your business and those of your associates.
#2 Inadequate SpecificationAn adequate specification includes references to the minimum structural requirements, exact type and size of underlayment, specific brands of adhesive, additives, sealers, sealants, membrane systems, specific grout colors, and a specific tile. A better specification will also refer to specific ANSI A108 standards, and the best type of installation specification will include a commence-and-complete schedule. Assuming that an installer is going to do the right thing is like putting elections in the control of politicians. Specifications are easily obtained from any tile installation material manufacturer. Following a manufacturer's instructions is essential to obtaining warrantee support should something go wrong.
#3 Inadequate StructureCeramic tile installations depend on a structure strong enough to carry dead and live loads with a minimum of flexing: deflection must not exceed 1/360th of the span when measured with a 300-pound concentrated load. For tiling,spanincludes the longest distance measured across an installation, as well as the smaller span between two joists or studs: structures supporting tilework must honor both concentratedanduniformdeflection. Industry standards limit on-center joist and stud spacing to 16-inches maximum. Joists smaller than 2-by-10 (2-by-8s and 4-by-6s, for example) are unacceptable. Engineered joists, regardless of what the wood manufacturers may tell you, must be installed on 16-inch centers-not 19.2-inches, not 24-inches. There are methods of dealing with some floors installed with 19.2 or 24-inch spacing, but the cost of additional underlayment and membrane systems far exceeds the cost of using the right joists and spacing.
#4 No Provision for Movement JointsUnless you are building with 400-year old technology and materials, the structure you want to tile will naturally move and flex. If the structure meets the requirements for tiling, normal, expected movement can be safely absorbed by movement joints, which are nothing more than an empty slot-usually a grout joint-filled with a resilient caulk or sealant instead of hard grout. The lack of properly located movement joints has been a factor in every failed installation I have ever inspected. wet-area installations made without a proper system of movement joints will leak water or moisture into the structure. Crack isolations systems installed without following the requirements for movement joints will fail to provide protection for the tiles. Since 1968, I have worked on thousands and thousands of residential, commercial, industrial, military, food service, and medical installations. Every one of those installations required a system of movement joints. The ANSI A108 standards clearly state in A-3.4.2 that, "Movement joints are a requirement for tilework". The lack of movement joints will also negate any claims you may have against a material manufacturer for a failed installation you performed. With practically every grout manufacturer offering a complementary line of color-matched caulks, there is no excuse for not building them into your installations.
#5 Poor Surface PreparationContrary to what you may have heard, paint, paint overspray, cutback adhesive residues, drywall compound (hard or soft), drywall compound dust, sawdust, wallpaper, metal filings, lunch wrappers, hardened ice cream and milkshakes, cigarette butts, ashes, oil, grease, tar, unidentifiable encrustations, abandoned sandwiches or other food items, urine, and feces will all prevent adhesive-type materials (thinset, organic adhesive, and epoxy) from sticking to surfaces. A good specification will refer to the need for cleanliness, and give you an out if you have to stop and clean up residue made by a unconcerned construction worker. A reasonable amount of dust and dirt is to be expected, but if you have to cleanup behind an indifferent electrician, carpenter, plumber, drywaller, painter, or other tradesperson, your specification should allow you to bill the general contractor or responsible party. If you are a general contractor who lets tradespeople trash the site, you need to go back to school and learn basic hygiene; if you are an installer, learn to put realistic cleanup costs in all bids, proposals, and estimates.
#6 Inadequate WaterproofingTwo pieces of tar or tar-layered kraft paper, overlapped by two inches, is often considered waterproofing by unskilled, untrained, unreliable installers. The fact is, this arrangement actually promotes the transmission of water and moisture through capillary attraction. More than 2,000 years ago, the Romans (as did other cultures before them) recognized the need for waterproofing tile installations in wet areas, and never incorrectly assumed that tile and grout, alone, could stop water. They very correctly realized that tiles and grout make an excellent covering and protection for the waterproofing that lies below. Waterproofing for tile requires a sheet that is fully sealed to prevent water from migrating up, down, or sideways. In my opinion, puncturing a membrane with thousands of fasteners just does not make sense. Insurance statistics tend to fully support that position as more and more people want tile in their homes, and the problem of waterproofing becomes an epidemic. I recommend positioning waterproofing membranes between the tile and the setting bed to eliminate any absorbent mass that can become waterlogged and a potential health and safety risk.
#7 Poor Housekeeping Between LayersI often judge how smoothly things will run on a particular jobsite by looking at the trash, debris, and garbage that is either strewn around, or neatly disposed in a dumpster or other trash bin. On sites where there is little trash, I generally find a respectful attitude between trades. But when there is garbage all over the place, I expect to find trash and unwanted debris on every single layer of the installation if nobody is around to monitor the behavior of the disrespectful morons who do the trashing. For this reason, I never contract any installation that does not include a provision for cleanup and for staying off the tilework until after the proper curing period for all materials used. When working with an unfamiliar GC, my backcharge rate for unexpected cleanups caused by the careless behavior of other trades is generally 2-300% of my regular labor rate. Since instituting this policy, I have never had to charge one cent for excessive cleaning. Even better, I don't have to go through the frustration of finding garbage all over the place every time I show up at the jobsite.
#8 Improper Material UseIn the process of analyzing tile installation failures and examining materials that are used, I have identified adhesive products specifically designed for making automotive gaskets, wallpaper paste, low-strength art and craft glues, duct tape, basement waterproofing coatings, hot glue, construction adhesives, double-sided tape and more. As for grout, I have seen plaster of Paris, wood dough, thinset mortar, as well as some mystery materials. For waterproofing, there is unsealed tar and other construction papers, wood deck sealers, wax, paraffin, oils, shellac and other coatings. For crack isolation systems, I have ID'd duct tape, scribing felt, 15-pound tar paper, copper flashing, and silicone caulk. None of these materials have been rated for use with tile, tested for compatibility with other tile installation materials, or given general approval by the tile industry.
As well, I have been on projects where the very best tile installation materials were specified, but there are no instructions on-site, and as a result, the materials are used improperly and another installation that should last the life of the building fails. If you are installing tile, use materials made specifically for the purpose, single-source all materials if possible, and make sure that manufacturer's printed instructions are readily available on-site.