Ask The Experts – June 2016

SponsoredbyLaticreteQUESTION
I have a bathroom that was just retiled: floor, tub and shower walls, using ceramic tile, and a polymer-modified, cement-based, sanded grout with a stain-resistant additive. There are a few areas where the grout has set up like powder and can be rubbed out. I’m looking for some reasons that could cause the grout to set up like powder and fall out.

ANSWER
Selection, mixing, installation, curing, cleaning and environmental conditions at the time of grouting all play a critical role in the success of the installation. There are many potential reasons for this to have occurred.

Most are related to improper preparation, mixing, proportioning of powder and liquid, slaking, re-tempering or curing of the grout. Environmental conditions at the time of grouting and curing such as exposure to hot air flow, direct sunlight, a very dry atmosphere or freezing could also cause this condition to occur.

Over-washing of the grout immediately after packing the joints or cleaning cured grout with acidic cleaners may contribute to this problem.

In some instances, a very highly-absorptive tile or foreign material in the joints may cause rapid dehydration of the grout that may lead to this happening.

Without knowing the particulars at the time of your grout installation it is not possible to narrow it down further to a specific cause or group of causes.

– Mark Heinlein,
NTCA Technical Trainer

FURTHER COMMENT
That is very helpful. What would the needed fix be regarding the powdery grout? Does it have to be removed and re-grouted?

RESPONSE
It may be possible to slowly rehydrate the grout by misting with water and covering with kraft paper for several days and re-misting as needed. However, since an additive other than water was used to mix the grout, I would contact the grout manufacturer and ask their opinion regarding rehydration. Otherwise, it will likely be necessary to remove the grout. When removing the grout, take care to not chip the edges of the tiles or damage the waterproofing system under the tiles. – M.H.

QUESTION
This is actually a tool question. I am looking to purchase a snap cutter and wet saw capable of handling larger format tile (up to 48”). Any suggestions?

ANSWER
It certainly is important to have the right tools for the task at hand and to invest in quality tools that will perform well for a long time.

There are many manufacturers that produce the type of equipment you are looking for. While I can’t provide a recommendation for a particular make or model, I can give you a listing of some of the tool and equipment manufacturers that currently sponsor Partnering for Success and are Workshop/Educational Program Trailer sponsors. Some of them make the type of equipment you are looking for.

I recommend you take a look at what these manufacturers have to offer and talk to other craft persons that may have experience with similar tools.

Here is a list, but it may not be all inclusive:

  • Alpha Professional Tools
  • Corona Bellota
  • Dewalt
  • European Tile Masters
  • Husqvarna
  • Mark E Industries
  • Marshalltown
  • Miracle
  • MLT
  • Progress Profiles
  • QEP
  • Rubi Tools
  • Russo Trading Company
  • SGM
  • Tuscan Leveling

It doesn’t appear that you are a member of the NTCA. As a professional tile contractor you will find membership to be extremely rewarding and can get in on the effort to achieve Qualified Labor status and grow your professional potential. There is more information at www.tile-assn.com or you can contact me for information how to join this amazing group.

Thanks for the contact and good luck with your research!

– Mark Heinlein,
NTCA Technical Trainer

Ask the Experts – May 2016

SponsoredbyLaticreteQUESTION

Is there any TCNA or industry information that indicates that rounded-top porcelain cove base is not meant for situations where tile is installed on the walls above the base (since it has a rounded top)? I’d also like to know how the cove base is to be installed in conjunction with floor tile. I stated in my RFP to “install metal trim strips when coordinating porcelain tile pieces are not available.” Given that the cove base option for a selected tile series has a rounded top and foot, this causes a potential for an unclean install. The options that the contractor has given us are:

  • Using the wall base and filling in the rounded top with an enlarged grout joint,
  • Cutting the wall tile and butting it to the floor tile with either a grout or caulk joint at the connection, or
  • Field-cutting the rounded tip of the wall base off

These are not preferred options for the government, as these lead to maintenance issues down the road for the facility.

Do you have any idea how I can respond to this or help with any industry or TCNA info? Thanks so much!

ANSWER

There is no such language in the TCNA Handbook or in any of the ANSI manuals.

I believe that the #3 solution is the proper method, and how my contracting company usually accomplished this detail if round top cove was the only cove available (if cove was required). Be sure to stone the cut, and although it will have a slightly different appearance than a factory edge, it will not be a maintenance issue. Since the tile cove is round footed, it is designed to be top-set.

There is another option that is very effective, if somewhat more expensive. Profile and edge manufacturers make stainless steel coves (with corner trims available) with different sizes available to match the thickness of your tile. Very beautiful, easy to install, and cool, too!

If cove is not required by code, then just use the field tile at all inside corners with a joint filled with foam backer rod and ASTM C920 sealant (100% silicone or single part urethane). Be sure that the tile is not set tight and that the joint is completely free of mortar and grout.

– Michael Whistler,
NTCA technical trainer

QUESTION

We are currently working on a project that includes 30,000 sq. ft. of penny round tiles that were manufactured in Japan. It’s our understanding that penny rounds are classified as a specialty tile and therefore, very little criteria has been set regarding the mounting of them. We are having some issues with the specified product and need a third party to evaluate the mounting of the tile. Can you offer some assistance or point us in a direction regarding mounting issues with mosaics, in particular penny rounds?

experts-01 Attached are pictures of some of the mounting problems, including inconsistent spacing, sheets not being square and excessive mesh where the sheets meet up with one another. Another problem is that the individual tiles release from the mesh backing as soon as they get wet (from thinset).

may-experts-02Two manufacturers’ reps were here last week to review the problems. Their solution is to either send us a video or one of their Japanese installers to show us how to install the tile. As you may imagine we took exception to their suggestion. We have plenty of experience with the installation of penny round tile and have processed through many issues regarding sheeting and wall-washing concerns. What we are in search of, is some guideline or criteria that we can show ownership so they can assess their expectations more in line with industry standards. Any assistance you can share with us would be greatly appreciated.

ANSWER 1

You certainly seem to understand all of the issues and have the experience to install penny round mosaics, which are difficult at best. The tiles you have been provided appear to have an especially flimsy mesh backing, and the inconsistent spacing and water-soluble adhesive is not going to help matters.

Obviously, a proper substrate that meets minimum deflection and flatness requirements and using the correct mortar and troweling method to achieve a minimum of 80% coverage on each tile with no squeeze-through will be critical.

I’m almost thinking that to have the manufacturer send their installer to show you how it’s done (for the duration of the project) might be a way to bring the manufacturer on board with some liability for the installation.

Has all of the tile been manufactured and delivered? Have you discussed the matter with the owner and architect?

Other than what Katelyn has provided below and the general workmanship requirements found in the TCNA Handbook and ANSI standards, I am not immediately coming up with anything that I can send you. I will check with my colleagues and get back to you.

Perhaps the best approach will be to hire a recognized consultant to come in and serve as a third party to view the tiles and installation area and scope of work and provide you with a written opinion.

– Mark Heinlein,
NTCA technical trainer

ANSWER 2

From a third party testing lab’s perspective, there is no way to measure mounting variation of penny round, mounted ceramic mosaic tiles. The mounting variation test methods for mounted tile are only performed on square mosaic tiles. I’ve included an excerpt from ANSI A137.1 Specification for Ceramic Tile below:
9.5 Test Method for Mounting Variations
9.5.1 This method is only valid for mosaic tiles with the following characteristics:

  • Nominally square
  • Nominal sizes of 1 inch x 1 inch (25.4 mm x 25.4 mm) to 3 inches x 3 inches (76.2 mm x 76.2 mm)
  • With straight edges

Our lab does not provide reports based on expert opinion so you may need to hire an independent consultant if that is something you are looking for. Please let me know if you are interested in an independent consultant and I’d be happy to send you the contact information for one.

– Katelyn Simpson,
TCNA laboratory manager

Ask the Experts – April 2016

SponsoredbyLaticreteQUESTION

I am installing an indoor/outdoor patio for a continuous look on a cement substrate. The tile is 16” x 48” porcelain. The outdoor portion will be raised approximately 2” with a mud float. Should I use a bonded mud float or install a cleavage membrane? Additionally should I reinforce the float with lathe or not? Finally, I am in Austin, Texas, so I am wondering if I should put a membrane on top of the float to help prevent problems when there is a rare freeze. Thank you for your expertise.

ANSWER

Thank you for contacting the National Tile Contractors Association.

The closest TCNA Handbook for Ceramic, Glass and Stone Tile Installation method to follow for the exterior portion of this project is F103B. This method details a wire-reinforced mortar bed (maximum 2” thick) on top of a drainage mat/system. A drainage mat makes an ideal cleavage membrane since it promotes quicker evacuation of water from the tile/mortar bed system. Refer to TCNA Handbook methods F103B, F111 and F121 for details including specifications for cementitious bond coat mortar.

Sloping away from the structure is required for any exterior area, both for the substrate and the mortar bed. A minimum slope of 1/4” in 12” of horizontal run is required and is the typical specification to meet code. The slope of the substrate and the mortar bed need to match each other to produce a uniform thickness mortar bed. Prevention of water flooding back to the structure is the main reason, but slope and drainage are also a great help in reducing efflorescence issues.

A waterproof membrane is a good idea as long as there is not excessive moisture in or beneath the slab, which can be caused by poor landscape drainage design or clay-type soils for an on-ground installation. Moisture in the slab should be checked before deciding to install a waterproofing or crack-isolation membrane. Most membranes are suitable for moisture presence up 5 lbs/1,000 sq. ft. Some manufacturers state their product can be used up to 12 lbs/1,000 sq. ft. Check with the manufacturer of the membrane to determine what their product can handle. Moisture in excess of 12 lbs/1,000 sq. ft. will require significant mitigation before the project can proceed.

It is critical to pay strict attention to the planning and installing of soft joints and expansion joints. Installation of a membrane does not eliminate the need for proper movement joint placement. Soft joints must be installed in the mud bed and tile in line with the control joints. Expansion joints must be installed in the tile every 8’ – 10’ in the exterior and in the interior section if it is adjacent to a large surface area of windows and glass doors. Expansion joints are also required at the interior/exterior dividing wall and all other interior and exterior walls, cabinetry etc. See TCNA Handbook method EJ-171 for more details.

To ensure acceptable lippage with the installation of the large format tile it is very important to begin with a flat substrate. Your mud bed flatness must ensure a maximum variation in plane of 1/8” in 10’. You will also want to consider a 1/3rd offset layout if the tiles have any warpage. A lippage tuning system may also be beneficial.

I hope this helps!
Mark Heinlein,
NTCA technical trainer

Ask the Experts – March 2016

SponsoredbyLaticreteQUESTION

I have a question regarding polished porcelain mosaic tiles. Polished porcelain is becoming more popular these days with so many “marble” looks being manufactured. I have a client wanting to use a polished porcelain for her shower walls and would like to use the coordinating polished porcelain 1.5” x 2.5” basket weave mosaic for the shower floor (it is not available in matte). Is it ok to use any polished porcelain mosaic on a shower floor? Please advise.

ANSWER

Small mosaics generally do not pose a slip/fall hazard in wet areas, even if they are polished. The grout joints are so closely spaced that they create a type of textured surface that lends good traction, even in wet areas with lots of water on the surface. Mosaics have traditionally been used in shower floors with high success and little risk of liability.

– Michael Whistler
NTCA Trainer

QUESTION

Our company has been asked to look at a marble floor that is staining and “rusting.” This has only started happening within the last year or two of the floor’s 15-20 year life. There seems to be no etching or loss of sheen (which does not rule out chemical absorption, I am aware). We have been assured that the cleaning process/chemicals have not changed. The floor is on concrete, with occupied space below, and no evidence of moisture-related damage in that area’s ceiling. Before tearing out this floor and replacing it, I would like to be able to suggest what may be the cause and possible solution prior to going in and having unforeseen issues. Any assistance would be greatly appreciated.

ANSWER

White marble tiles can contain deposits of iron. As a mineral, iron oxidizes and turns the marble yellow or brownish red when exposed to water or acids, similar to the way metal rusts. It is possible for the oxidation process to occur many years after the tile was installed. The rusting of the tile may have been initiated or accelerated if the tile installation has recently been exposed to a large amount of water or if the chemistry of the wash water has changed.

It is possible to check the water supply for iron. A plumbing supply store should be able to provide a test kit. If iron is detected, the water supply can be chemically treated to remove the iron.

The tile itself can be tested for iron content. A yellowed tile can be removed from the installation and sent to a lab for testing. If there is attic stock tile that has never been installed, it can also be tested. Comparing the test results of the tiles will help determine whether the iron content was native to the tile or introduced through the water supply.

The rusting process is a chemical change internal to the tile and is difficult or impossible to reverse. It may be possible to remove the stain by applying a poultice consisting of a thick plaster of a product called Iron Out, which contains sodium sulfites. Test a small area by applying the paste and keep it damp for several hours. Remove the solution with a wet vac and clean water. Make sure your wash water does not contain iron. If the stain is removed, the entire floor can be treated in this manner. The process will cause some etching and the surface will likely have to be re-polished.

If you determine iron oxidation is not the cause, you may discover the cleaning agents or the cleaning procedure has changed (such as using the same mop and wash water on the marble after being used in a dirty environment). Marble is porous and has naturally occurring pinholes. After years of wear, the surface of the marble may have become less polished and more open to absorption of dirt. Normal traffic or a dirty mop could be introducing dirt into the pinholes.

After you have ruled out iron mineral staining and suspect cleaning is the cause, it is possible to clean the marble with an alkaline solution. Test the alkaline cleaning solution on a small area before attempting the entire floor. The cleaning process will require scrubbing, which will likely dull the surface. The surface can be re-polished.

The size and scope of the project may determine the best course of action. Ultimately, removal and replacement may be the solution.

I will be interested to know what you discover in your investigation and the approach you take to correct the issue.

– Mark Heinlein
NTCA Trainer

Ask the experts – February 2016

SponsoredbyLaticreteQuestion

Our house is currently under construction. The contractor applied a 1/4” grout for the 7” x 20” wood look-alike ceramic tile. We want to know the standard application of grout for this kind of tile to prevent lippage. Hope to hear from you soon. Thank you.

Answer

Grout is an important structural component of the tile installation. Grout joint size is determined by a number of factors such as the grade of the tile, variation in tile thickness, warpage (cupping or bowing) within each tile, wedging (variation in a tile’s facial dimensions), installation pattern, and others. Depending on the quality and grade of the plank type tile you have described, we often see many physical variations that must be accommodated.

While design preferences and final appearance are also important considerations, the installer must factor all the variations to determine the appropriate grout joint width that will produce an installation with allowable lippage. Without personally knowing the factors of your installation, a 1/4” grout joint is not uncommon and may be the most appropriate.

– Mark Heinlein, NTCA presenter

Question

cracked-glassWe have had a lot of difficulty with two tiles that keep breaking with our shower install. We have no choice but to cut the glass tiles because there has to be an opening for the water. We’ve followed all of manufacturer’s suggested techniques: wet drill, drilling from the back etc. Do you have any suggestions?

Answer

Glass tile, particularly large format as these seem to be, can be extremely difficult to cut successfully. You stated that you are using wet drilling, so that leads me to believe you are using a diamond core bit (possibly 1-1/4”). You need to ensure that the hole saw is sharp (new diamonds exposed) so undue pressure is not exerted on the tile while being cut. Sharpen a diamond core bit (or diamond blade) by wet cutting several times through a very abrasive material such as an aluminum oxide rub stone or a piece of concrete cinder block. When you wet cut the tile, you need to use LOTS of water, as any heat build-up can result in failure. Also, drill very, very slowly, again to not exert undue pressure on the tile. It seems that cutting from the front AND back of the tile can usually give a successful result. Mark the tile on both sides, wet drill slowly half way through the face side of the tile and stop. Turn the tile onto its face, preferably on a towel to avoid scratching, and slowly wet drill from the back of the tile to meet the cut you previously made. This trick usually works.

One further point: many diamond core bits on the market come with a masonry type pilot bit. This bit needs to be removed for glass tile (and really any tile harder than a 4” x 4” or 6” x 6” talc body tile). Begin cutting with the core bit by holding the drill at a slight angle to the face of the tile, and with a steady hand, begin the cut. After cutting in about 1/16”, start slowly rotating the drill more and more upright until you have created a completely circular kerf. You may then begin drilling perpendicular to the tile (exerting very little pressure).

You probably do not have an abundance of extra tiles, so hopefully this will work for you on the first try. If you still experience cracking of the tile, you may need to enlist the help of an abrasive waterjet cutting company. Most cities and even towns have one these days. Just mark the tile, take it to the waterjet guys, and for a nominal fee they will make your cut. This method of cutting puts almost zero pressure on the tile.

I also noticed from your photos that the tile had cracked under an installed plumbing fixture. Tub spouts usually screw into place, and it is very easy for an installer to slightly over-tighten the fixture to get a nice tight fit, resulting in cracking. It is much better with glass tile to leave the fixture one revolution loose and to use a 100% silicone sealant (caulking) between the fixture and the face of the tile.

Hope this helps, and feel free to call me with additional questions.

– Michael K. Whistler, NTCA presenter

Ask the Experts – January 2016

Tampa-International-Airport-16

SponsoredbyLaticrete

QUESTION

I have a small tile job at the TIA (Tampa International Airport). The general contractor (GC) is directing us to start the work with temporary lighting that is not very good. We have asked that they place either the permanent lighting or temporary light “representative” of the permanent lighting so that we can see exactly the conditions for the installation.

I could have sworn that I read something at some point with regard to tile being installed in the lighting in which it is to be used.Can you help me with some type of literature on this item?

 

Tampa-International-Airport-16ANSWER

Thank you for contacting the National Tile Contractors Association. I am happy to provide you with some information to help you respond to your GC regarding the installation of tile under poor temporary lighting conditions that are likely not representative of the permanent lighting.

We are not aware of a requirement for the GC to install the permanent lighting before tile work commences. However, you are correct to be concerned about the location of permanent lighting and its potential effect on viewing the finished surface of the tile installation. The angle of natural or manufactured light on finished tile work may cause an acceptable installation to have an unacceptable appearance.

While there is no specific method that addresses installation of lighting, the 2015 edition of the TCNA Handbook includes a statement about various types of lighting and their effect on wall and floor tile installations. When proper backing surfaces, installation materials, installation methods, location of light sources and certain lighting techniques are not carefully coordinated, shadows and undesirable effects may be apparent on finished ceramic tile installations.

The 2015/2016 edition of the NTCA Reference Manual includes an extensive discussion of critical lighting effects on tile installations. This discussion is found in Chapter 5, “Special Installation Procedures,” and addresses many problems along with tips and preventive measures tile contractors can take or recommend before the installation begins. Also included is a series of photographs that boldly illustrate the effect lighting can sometimes have on a tile installation.

The success of your particular installation will depend on a variety of factors such as: flatness of the substrate (which will have a profound effect on the flatness of the finished tile surface); the type of tile being installed; the pattern the tile will be installed in; the inherent warpage of the tile; the grout joint width; any out-of-tolerance lippage of the finished tile installation, etc.

As required by ANSI, we encourage you to construct a mockup of the area to be tiled and illuminate it with an accurate representation of the permanent lighting installation. Have the GC or architect review the mockup and accept it in writing before beginning the tile installation.

If you are a member of the NTCA, please review pages 139 – 144 of the NTCA Reference Manual. There you should find all the information you need, including a sample letter you will be able to reformat as your own company’s formal communication to the GC and/or the owner.

If you are not a member of the NTCA, please visit our website at www.tile-assn.com or contact me and I will be happy to assist with your application.

Mark Heinlein, NTCA Technical Trainer

Ask the Experts – October 2015

ATE-1015

SponsoredbyLaticreteQUESTION

I’m writing you from the Tamp aarea. I’m a current NTCA member and have followed your writings for quite sometime. I’m a 30-plus year tiler and remodeler. I’ve run into a bit of a problem and I’m stumped, and wondering if you can help me out.

Recently I tiled a shower with 6” x 12” glass over waterproofing membrane. I’m getting some cracked tile on the field walls. First it was one but now I’m up to three. I used a 1/32” grout line and grouted with unsanded. Of course my setting material was unmodified. So please chime in as to why I might be having trouble. I would like to find a resolution before I make my repairs.

This glass product is some of the hardest glass I’ve ever worked with. Difficult to snap cut and wet saw cut with glass blade – it kept cracking in various places. I’m not sure if the quality of the glass poses a problem. Thanks for your help, thoughts and opinion.

ANSWER

Based on your description, it is likely surface tension or lack of flexural value in the glass and shrinkage of the thinset. Installing impervious glass over an impervious membrane causes a very long cure cycle. I have seen glass crack months after it was installed. Cracks when you cut say surface tension and shrinkage to me. It would be pretty expensive to prove that out but pretty sure it could be proven.

David M. Gobis CTC, LLC, Ceramic Tile Consultant

QUESTION

A condo complex called me to look at their elevators. Currently, they have five elevators with 1” x 1” mosaic that is crumbling after 10 years of use. They want to know what my suggestion is to replace it.

What have you seen normally go into an elevator? These are on the Gulf Coast and see lots of exposure to water. I see problems with the type of underlayment I would choose as well as the ability to adhere it to a metal floor. There is 3/4” between the elevator floor and the bottom of the door. I need material and installation recommendations.

ANSWER

I get this question fairly often or slightly different versions of it. Most often the cause of cracking tiles and grout joints can be attributed to excessive substrate deflection.

The elevator cabs chosen for these construction projects are not designed for tile or stone floor finishes. The manufacturer of these elevator cabs will list acceptable floor finishes that usually only include soft goods such as vinyl, carpet, and wood products. In order to be considered for tile or stone the substructure should be constructed in such a way as to not to deflect or “bend” more than a small amount under a concentrated heavy load. There are elevator cabs that are designed to meet these minimum requirements but they are usually much more expensive so they are not chosen in most construction
budgets.

As for installing tile in these most common elevator cabs that are not designed for such, it is risky and not recommended.

There are products available that may reduce the risk of cracking tile and grout joints such as epoxies, but no warranties from these manufacturers are available. I hope this information helps.

Gerald Sloan, NTCA Trainer

QUESTION

I’m a San Diego handyman. I hired a licensed tile contractor to tile some shower enclosures standard 32” x 60.” I have 15 years experience and installed floors and showers myself.

ATE-1015The installer basically put large +/- 2”x 2” by 2-1/2” high blobs of thinset on the back corners and center of the tile (5) and pushed it onto the wall, leveling the tile with the adjacent pieces as he went. It does not stick out proud from the finished wall because he used 1/4” backer board on the studs. I have only seen 1/2” used but the manufacturer’s website does “approve” 1/4” for walls. Nowhere in the code could I find mention of substrate thickness.

I am concerned about the structure and more importantly the grout. It’s expected to just rely on the thin edges of the tile to hold it. I won’t be using him again but the union guy backing this installation method has me confused. Is this an approved type of installation?

ANSWER

You are correct to be concerned about this issue.

Industry and manufacturer standards recommend 80% coverage at dry areas and 95% coverage in wet areas and exteriors (both with all edges and corners supported). It is almost impossible to achieve these high coverage percentages using the “five spot”
method.

Unfortunately “five spot” usage has become more prevalent in the tile industry in recent years due in part to the choice of large-format tile for the project, as well as the installer trying to install these large-format tiles over substrates that are not within proper flatness tolerances.

These choices by many installers are causing an inordinately high percentage of job failures. As far as using 1/4” backer directly over studs 16” o.c., I am uncertain whether that is an allowable practice according to the manufacturer.

Michael Whistler, NTCA Trainer

Ask the Experts – September 2015

0915-asktheexperts

SponsoredbyLaticreteQUESTION

I’m contacting you regarding talc on the back of tiles. Since there are no standards or guidelines regarding talc on the back of tiles from the manufacturer, what does your organization suggest for the tile installer? Are they required to clean this off, or can it be installed as is?

ANSWER

The talc is actually called “kiln release” and is used to stop tiles from fusing to the conveyor belts in tile firing kilns. Usually there is not enough to create a problem, but when there is too much, which will create bonding failures, you have two choices: wash the backs of all the tiles and allow to dry, or back butter all the tiles with the flat side of the trowel.

– Michael Whistler, NTCA presenter

QUESTION

I have a question regarding the TCNA Handbook. Is it required to have a soft joint between the floor tile and the vertical tile bullnose base?

ANSWER

According to Method EJ- 171 in the TCNA Handbook, you must provide movement accommodation at all perimeters as well as all changes in plane. So if you install your floor tile first, you must provide an open space (or sealant-filled joint) between the floor tile and the wall (or cabinet, toe kick, tub, etc.). Then set the tile base on top of the floor tile, thereby covering the visible gap.

If you are installing the base first, you still must have perimeter movement accommodation, accomplished by leaving the joint empty of mortar and grout and filling with compressible backer-rod and sealant, or use a pre-manufactured perimeter movement joint (available from a number of manufacturers). These details are shown in Method EJ-171 in the TCNA Handbook.

– Michael Whistler, NTCA presenter

QUESTION

We are dealing with a 70-plus hollow-tile issue. Our villa was built and the tile installed in 2011. The hollow tile started in January 2015 with two hollow tiles. As of May 2015, there are 70-plus hollow tiles. We would like to know the cause of the problem and the appropriate resolution.

ANSWER

Hollow tile is usually caused by bond loss. The timeline you describe is relatively common when tile is not provided with appropriate movement accommodation, an important part of any tile installation.

– Dave Gobis, CTC, CSI, Ceramic Tile Consultant

INQUIRY, continued

The original installer concluded the installation was good but the concrete settled, therefore the tile detached and became hollow. With this being the situation, he said this is what is supposed to happen (meaning the tile should become hollow rather than cracking) and that we are lucky we don’t have more cracked tile (about 10 now). He wants to inject the 70-plus hollow tiles with epoxy and replace the cracked grout and drill holes from the injection. This view is supported by the builder with whom the floor is under warranty until December 2015.

The two independent tile companies both concluded that the tile was improperly installed and needs to be replaced to address the underlying problem and that when tile is installed properly this should not happen (meaning 70 hollow tiles).

Our villa is in Venice, Fla. There is about 900 sq. ft. of ceramic tile. There are hollow tiles in all six tiled rooms with one room not being connected to the others. The hallway is where two hollow tiles started and now nearly all the tile in the hallway are hollow with cracked grout.

If you could advise as to the proper procedure to correct this tile issue, we would greatly appreciate it. Please contact us if you have any questions or need any clarifications. Thank you for your help.

ANSWER, continued

Your original installer is uneducated, ill informed, and incorrect.

I can’t speak for the other two tile contractors but they know more than the first one.

Injecting is something done to mask installation shortcomings. Based on your pictures, there is minimal bond to the surface, plus I still believe, a lack of movement accommodation. This is a very common problem and one that occurs frequently in Florida. I have been to Florida numerous times for this issue for several years now. Based on what I see replacement is probably appropriate.

– Dave Gobis, CTC, CSI, Ceramic Tile Consultant

0915-asktheexperts

Ask the Experts – August 2015 “Green Issue”

thermal-heat

SponsoredbyLaticreteQUESTION

I was referred to you through my tile supplier. I am a general contractor and I would like to ask you a question regarding a former project of mine.

I took on a tile job for a person in an electric wheelchair. The chair weighs several hundred pounds (plus the amount of the person, probably 170 lbs-180 lbs). Before I started, the old tile in her hall, kitchen and entryway had broken, resulting in loose tiles. She had told me that her wheelchair was the cause of the damage. Those tiles were 12” x 12”, installed long ago. She wanted new tile installed throughout the house. I installed 18” x 18” ceramic tiles. I used flexible thinset, and 1/4” cement board. I staggered the board and used screws (in the correct sequence) as recommended by the manufacturer’s instructions. The joists are 24” center. Expansion joints were used throughout.

I have installed many jobs with these specs in the past without any issue whatsoever. The customer has said some of the tiles have loosened and the grout is cracking. I suspect this is due to the wheelchair (which is, of course, out of my control). I am looking for your opinion if you can share it with me based on this information.

ANSWER

There is no industry method for 1/4” backer over 24” centers. I understand it is done often and if all the stars are aligned and everything done correctly it might work. However, with a rolling wheel load extra precautions would be required. The PSI of a wheel is much greater than normal foot traffic. The deflection between 24” centers is too great. Flexible thinset doesn’t compensate for lack of a supporting structure. You need another layer of plywood at a minimum and I would consider some bridging as well to stabilize the truss/joist.

David M. Gobis CTC CSI, Ceramic Tile Consultant

QUESTION

I’ve been setting tile on and off for the past 11 years, and it wasn’t several years after getting started that I learned about the importance of using expansion joints in tile. That’s thanks to working under Mike Hearn, one of the few Certified Tile Installers in Atlanta, Ga.

I’d like to get your opinion on one project. I just moved to Guayaquil, Ecuador with my wife to be closer to her family. My father-in-law is in the final stages of building a house here where all the flooring and bathrooms are tile. They are nearly finished installing 24” x 24” rectified porcelain upstairs and 24” x 24” non-rectified porcelain downstairs. Each level is approximately 1000 s.f. and is tiled continuously throughout the entire floor.

On the rectified tile, the joint looks like maybe 1/32” and on the non-rectified it looks like about 1/16”. I emphasized to my father-in-law on several occasions the importance of expansion joints.  I’ve even pointed out how you can see them used here in malls and many commercial applications.  Well, they did not use any – and they grouted in hard around the perimeter.

thermal-heatThe subfloor is concrete and the walls are concrete as well. The first thing he said when I walked in was that he checked on it, and because here the temperature variations are minimal, there was no need for expansion joints. This is frustrating because they could have at least left a gap around the perimeter without any aesthetic change since it will be covered by base.

So I did some research on temperature variations here in Guayaquil. The average monthly temperature variation is only 5 degrees Fahrenheit, that’s the difference between the lowest average monthly temperature and the highest average monthly temperature. The average daily variation, and also the max, from day to night is 16 degrees Fahrenheit.

The only thing I could think to do about it now would be to cut out expansion joints around the perimeter of the rooms, but I’d like to get your opinion before I confront my father-in-law.

I know in the end this is his problem, but having worked in the industry I hate to see so much money invested into projects that will likely fail prematurely.

ANSWER

I had an argument like this on a project in Hawaii. They said the other projects had been in more than 20 years with no problems and chose to not use soft joints. A few years later one of those projects lost bond.

Temperate climates are helpful, but:

• Soils do move

• Tile gains size long term with moisture absorption from the slab, and cleaning.

• Sun exposure creates unequal thermal mass.

• Large tile has a fraction of the grout joints smaller tile does. Compression strength of grout is, maybe 1,500 lbs to 3,000 lbs. Compression strength of tile, laterally, is 25,000 lbs – 30,000 lbs. Big tile, fewer sacrificial grout joints. My experience is if you have a 12” x 12” and a 24” x 24” in the same installation, like a border, the 24” will go first. I see this a lot on malls where they have a fair amount of footage to observe.

• Small joints or butt joints have nearly no buffer of sacrificial grout.

Based on temperature range alone, this is likely not a problem. But, everything in a building moves and it all moves at different rates. My opinion would be this is low risk – not no risk – unless it is wet soil and sunny, then raise it a few notches. The picture attached shows the different temperature early in the morning on a floor that received sun exposure (yellow) and the shaded area (purple).

I have been down to Mexico a half dozen times in recent years in the Southern part of the country for bond loss due to expansion issues.

– David M. Gobis CTC CSI, Ceramic Tile Consultant

Ask the Experts – July 2015

1-ate-0715

SponsoredbyLaticreteQUESTION

I have a new construction (2008) post-tensioned slab where very small cracks have developed in my travertine tile flooring (ground floor). I had a contractor come out and he said that the standards recommend installing a slip sheet before applying the tile. Is there a professional article that I can use to back up my assertions to the original tile contractor that there should have been a slip sheet?

1-ate-0715ANSWER

Since your installation was done in 2008, that year’s industry standards must be consulted. The 2008 TCNA Handbook for Ceramic, Glass and Stone Tile Installation states in method F113-07 in the Limitations section that “Method F111 is the preferred method over precast concrete floor systems, post-tensioned concrete floor systems and other floors subject to movement or deflection.”

Method F111 is an unbonded (includes cleavage membrane) wire-reinforced mortar bed, minimum 1-1/4” and maximum 2” thick. Hope this helps.

Michael Whistler, NTCA presenter

QUESTION

Could you direct me to a simple method to calculate the regulated flexural strength of cementitious floor tiles (i.e. equation or formula) for various areas of application (i.e. residential use vs. commercial use vs. industrial use)? There must be an ASTM standard for these floor coverings and a simple way to determine these flexural strengths depending on the length/width/thickness of the tiles. European standards use EN 14411 with the following formula: Breaking force F(N) = 2 x ß x h² x b /3 x L in which:

1. ß is flexural tensile strength of the tile (N/mm2)

2. h is tile thickness in mm

3. b is tile width in mm

4. L is tile length in mm

Thank you for the time that you will allocate to this information request.

ANSWER

There is no standard for cement floor tile, though there have been discussions over the years.

Relative to your question about flexural value, the U.S. does not address that issue in ceramic tile well. In addition to EN 14411, there is EN 14617 for agglomerated stone. I have found the 14617 standards of greater value when considering cementitious floor tile, primarily in the area of dimensional stability. On flexural value, architects typically put the cementitious tile in section 09300 and treat it as floor tile. When I get a claim on cement tile, one of the tests I often use is ISO 10545-4 because it has a standard for flexural value for ceramic tile. While ceramic is >30 N/mm2 and porcelain is 35 N/mm2, I often find cement tile anywhere from 10 to 17 N/mm2. This requires a surface with less curvature than a conventional tile to be successful. I have had well over a dozen large claims on cementitious floor tile. In the majority of them this was an issue and the dimensional stability was a problem as well.

David M. Gobis CTC CSI, Ceramic Tile Consultant

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