This being the Surface Prep issue, it would be a great month for me to write the editorial but alas that is not my job for FCI, for which maybe I should be thankful. Most often, I do not have strong feelings one way or the other about editorial directions or issues. As an educator my choice of methodology has been to deal with fact and it is very rare that I have an opinion and wish to editorialize about anything, publicly anyway. Lately, I am developing an opinion about something and that is those who consider themselves floor covering installers. There have been numerous recent events (failures) passing my desk that have involved many substantial and well-known floor covering stores. Tile has certainly been a boom to many floor covering professionals who have embraced it and for others a curse. Properly selling ceramic tile and installation is certainly much more challenging than most products. If you disagree, you're doing something wrong.
Floor covering installation itself is in my opinion a difficult and challenging occupation given substantially less appreciation and remuneration than it deserves. Those who consider themselves floor covering specialists have to be well versed in not only numerous types of products and their basic installation requirements, but possess a general knowledge of building construction. The majority of basic installations can easily be accomplished using a professional floor covering installer. However, basic is the keyword here. In estimating or assessing any structure for a successful ceramic tile installation, much greater knowledge is needed than a general understanding. This is where a ceramic specialist is needed. Measuring and logistical issues are important consideration on a ceramic project, but there is much more information needed to make informed choices and pricing the job accurately.
Ceramic tile installations have some major differences from other floor covering products. First and foremost, is the need for the structure to support the installation. This is area that even a tile specialist can struggle with unless he has a degree in engineering and knowledge of all components of the structure. Many of us have heard of and some even check for floor movement, known as deflection. Most reading this article are aware the requirements for deflection in ceramic tile installations are L/360 or 1 360th of the span and some even may be aware that is using a 300-pound point load measurement. Many mistakenly believe this all to be a sole function of the floor joist support when in fact it applies to the subfloor panels as well. There are numerous ways that people employ to check for this ranging for using lasers with a 300-pound load in the center of the room to the famous water glass jump test. None of these methods nor others will give an accurate assessment. Most building codes require L/360 deflection for dimensional lumber and some recommend L/480 for engineered floor joist. The engineering used to secure building permits is based on the stated use of the structure. IF tile is being used as an optional flooring material rather than called out in the plans, it would be very seldom that the additional support required would be added, "Just in case". Most building codes require what is known as a load rating of 40/10. 40 pounds is the anticipated weight of people and furniture known as live load and 10 pounds is the weight of the structure, known as dead load. If tile is to be used, there is an additional dead load requirement that will vary with the installation method selected. It could be as little as 3-4 pounds using a membrane system, 7 to 9 pounds using a backer board, or as much as 20 pounds using a 1 ¼-inch mortar bed. So far, we are just dealing primarily with the joist capabilities, now we must deal with the sub-floor panel or existing floor assembly. The vast majority of true deflection issues, such as cracked tile occur due to lack of adequate panel thickness. This is where things get a little more difficult to understand. There is no requirement under building code to provide a concentrated load rating for deflection of the area in-between the floor joist unless it is stated in the intended use of the structure. Most building codes in the US are modeled on the International Residential or Commercial Code, IRC and IBC respectively. These recommendations are currently in use by 45 of the 50 states. Here is what the code says about use of the structure;
Floors and other similar surfaces shall be designed to support the uniformly distributed live loads prescribed in Section 1607.3 or the concentrated load, in pounds, given in Table 1607.1, whichever produces the greater load effects. "Unless otherwise specified, the indicated concentration shall be assumed to be uniformly distributed over an area 2.5 feet by 2.5 feet and shall be located so as to produce the maximum load effects in the structural members."
Recently the tile industry recommendations have been changed to reflect code recommendations. If it all sounds a little complicated, it is. The best way to avoid problems is to follow the recommendation contained in the Tile Council of America handbook. All of the floor rated assemblies listed will perform over properly constructed code compliant structures. In days past, one could look at the floor structure and make an educated guess on performance. Those days have pretty much passed by. These requirements hold true for above grade concrete structures as well. Because use of concrete in building structures requires a substantial amount of performance engineering, failures due to deflection are rare, but certainly not impossible. With concrete floors, we also have a single plane of movement that does not exist in wood structures. If all this confuses you, I am making my point about a specialist, if it does not confuse you, move to the front of the line.
Once we have a supporting structure and proper subfloor, we need an appropriate underlayment. For new construction, the choices can be simple; we have a multitude of backer boards, membranes, or wood underlayments to choose from. With ceramic tile, unlike other floor covering products, there is no such thing as a single layer floor that is certain. Where things get a little more complex and require a specialist is in remodeling. Often we are asked to go over existing floor covering such as sheet vinyl or vinyl tile. Often, these products are installed over thin wood underlayments using staples. I even have photographic proof of a tile and underlayment installed over a commercial level loop! Here is where things get both risky and expensive. In the perfect world, we would remove all such underlayments. That is not far from the real world approach needed. Removing underlayment(s) and vinyl products eliminate the compressibility that comes with each layer of a flooring sandwich. Because the customer desires the best floor for the lowest reasonable price there will always be those who take the leave it all in place approach. Locally, we would call such an installation a resale special. They are fine for dressing up the home and passing the problem and expense on to the next owner. But, this type of installation is not for those who desire long term performance and a return on their investment. Manufacturers will have us believe we can tile over nearly anything, which is true, but durability is another issue. It takes a seasoned tile specialist to recognize what will and will not work.
Once we have our substrate selected it must be both clean and secure. While it may sound outrageous to some, and non-competitive, in my company we sanded or mechanically cleaned and vacuumed all concrete or wood substrates prior to installation, whether small residential projects or large commercial ones. This assured a good bonding surface and also removed minor surface imperfections. There are many companies that provide various types of equipment for mechanically cleaning or roughening the substrate. Cement bonds to microscopic capillaries in the surface. Even with the addition of a latex or polymer component, a floor cleaned in this manner will achieve a superior bond. We also found the time (cost) used to prepare floors in this fashion was not much greater than scraping and broom cleaning. If for some reason you choose to roll the dice and install over vinyl tile or fully bonded sheet vinyl, the floor finish must be stripped, not just cleaned, to achieve an adequate bond. Clean is the word for substrates.
We have finally worked our way to setting materials. This is an increasing area of confusion for everyone. Times used to be much simpler. Each manufacturer had maybe 5 or 6 different thinset mortars, a few types of liquid additive, and two types of mastic, floor and wall. For grout we had sanded for joints an 1/8" and over and unsanded an 1/8" and under. Even with that limited selection, we always sarcastically felt a chemical background was needed to make the proper selection. I would argue that is not very far from true anymore. Selecting a thinset today can be mind boggling to say the least. There is no easy way to assess performance, nor are their any standards currently in place to allow specification of performance. Today most setting material manufacturers have over 30 different thinsets available. There are at least 10 very different types of grout among setting material manufactures and only slightly less choices in mastic.
Today we have large tile, impervious porcelain tile, glass tile, homes (allegedly) built to minimum code compliance sans the added load for tile, smooth concrete, premature traffic, and poor environmental conditions just to name a few of the biggies. This from my perspective is one of the greatest challenges we face in the sale and installation of ceramic tile and a good part of my choice of topics for this months column. Retailers and installers alike tend to gravitate to the least expensive product that will do the job. Truth be know, most will do the job in a minimally acceptable fashion assuming everyone else has and will do their job. Making that assumption is a very poor choice as it is highly unlikely. Setting materials are the least expensive component in the installation process even if premium materials are used. Hopefully this selection process may get a little easier in the future. The American National Standards Committee and the International Standards Organization are both currently working a standard that would easily identify the performance properties of various thinsets.
I know much of this may sound like old news to many and it is much more editorial in nature than the technical type material I usually write but there is a reason for it. Recently, there has been a cornucopia of very well-known floor covering stores with good installers whom, while having every intention of doing a great job for their customers, sadly failed to accomplish their mission. The reasons are typical such as
- Premature traffic which could be resolved using the appropriate thinset.
- Using epoxy over a damp surface causing a release, water over epoxy yes, under, no.
- No thinset under the backer board causing cracked tiles and grout.
- Using liquid waterproofing products and not having adequate film thickness to make it waterproof causing a weeping installation, which can be much more damaging than a leaking installation.
- Going over curing compounds upon which the entire floor released as the furniture was being moved in, something that could have been easily noted using a water drop test.
- Installing large glass tile and using thinset to level the substrate causing the glass to crack as the thinset cures (shrinks).
- Installing porcelain tile with "pre-mixed" thinset in a basement. It is not cement.
- Backer board installed over 5/8" CDX sheathing as a subfloor. No such thing as CDX and tile; additionally, all subfloor panels must be tongue and groove.
These are all calls or emails received the week prior to my article being due. Without exception (or admission anyway) each one professed lack of knowledge on the issue or said, "That's the way we always do it and never had a problem before." There are numerous tile industry associations that do their very best to create sound recommendations, standards, and help educate those with the desire to understand ceramic tile and installation. Many are listed in the back of this magazine. Maybe it is time to join one or seek out some education so you can make tile as financially rewarding as it is challenging.