Tech Tip Tuesday: Q & A With NTCA Training Director Mark Heinlein

Consumer Question:

Hi! Recently, our new tile floor began cracking. Our builder took up the damaged areas, fixed deflection, and replaced damaged tiles. Now, more tiles in other areas are cracking. Is it standard practice to continue piecing the floor together or is it better to rip out the whole floor?

Answer:

Thank you for contacting the National Tile Contractors Association.

It is not at all standard to have to make repairs like this to a new tile installation.

What is standard is to ensure the structure including the subfloor and substrates that will support the tile installation are properly engineered, designed and constructed before the tile installation begins. There are standard requirements to meet tolerances for deflection.  When deflection and substructure requirements are met, tile installations can be designed and installed using additional tile industry standards, methods, best practices and techniques.

The primary tile industry standards are found in these publications:
American National Standards Institute Specifications for the Installation of Ceramic Tile (ANSI A108)
American National Standards Institute Material Specifications (ANSI A118)
Tile Council of North America (TCNA) Handbook
In addition to deflection, there may be other factors that could be leading to this failure in your tile system.  Tile installations are complex.  Every aspect of the installation must be performed according to industry standards and material manufacturer instructions to ensure a long lasting successful installation.

Ask your tile installer which standards and methods from the above listed publications they followed to install your project.

Is your tile contractor a Ceramic Tile Education Foundation Certified Tile Installer (CTI)?  CTIs are recognized by the tile industry to have the necessary knowledge of these industry standards along with the proven skills and experience to construct long lasting tile installations.  You can search the list of CTIs in your area at this link:  https://www.ceramictilefoundation.org/find-certified-tile-installers

Is your installer an NTCA member or an NTCA 5 Star Contractor?  NTCA member contractors can be located here:http://www.tile-assn.com/search/custom.asp?id=2759  Membership in the NTCA is a valuable resource for any professional tile contractor or any contractor who installs tile.  NTCA is committed to improving installations and performance of contractors throughout the tile industry.  Our primary mission is training based on the tile industry standards I described above.

NTCA 5 Star Contractors that employe CTIs can be located at this link:  http://www.tile-assn.com/search/custom.asp?id=2838

Every installer should own and be familiar with the standards, methods and details that guide the tile industry.  If your contractor is not familiar with the standards or if they are not an NTCA member or Certified Tile Installer, I would be happy to discuss with them the importance of these programs.  Please feel free to have them contact me, or Jim Olson at [email protected] for more information.

The NTCA and the entire American tile industry want you to have a beautiful and functional and safe installation that will stand the test of time and that will make you happy and comfortable and proud to own. Employing Certified Tile Installers and NTCA member contractors is a step in the right direction to ensure a successful tile installation based on tile industry standards.

I hope this helps.

Mark

Ask the Experts – August 2017

QUESTION

An architect has requested my input relative to developing a labor and material specification for installing new porcelain floor tile over existing granite floor tiles in a high-traffic lobby in a commercial office building. Can you direct me to any relevant literature or information that addresses such applications? Thanks.

ANSWER

I suggest referring your architect to the 2016 TCNA Handbook methods TR611, TR711 and particularly TR712. Please note that if the installation is not, or cannot be made acceptable for tiling over with a thin bed system, Method F111, or another method, may be required.

As described in TR712, it is critical that the existing installation be sound, well bonded and without structural cracks. It must be determined if the existing installation will properly support the new installation. The existing tile and its bond to the substrate and the condition of the substrate will all reflect on the performance of the new installation. If there are existing structural cracks, their cause will have to be explored before using the existing surface as a substrate. It is advisable to consider the need for a partial or full crack isolation membrane. Those methods are F125-Partial and F125-Full in the TCNA Handbook.

Any existing expansion in the substrate beneath the existing installation must be honored in the new installation. TCNA Handbook Method EJ171 will be the reference to all expansion and other types of joints that must be honored and designed and installed into the new system. Note that EJ171 states the architect shall specify the location of any expansion joints and other soft joints throughout the field and other locations such as the perimeter and any change in plane. Have the architect specify in writing (via drawings) where these are to go and which materials and EJ171 details should be used to construct them.

Checking for the ability to bond to the existing tile is imperative. If there are sealers or oils or waxes, etc., on the existing sur- face, they must be removed. If the tile is highly polished, it will likely require mechanical abrasion to allow the bond coat to adhere. I suggest doing a simple bond test by mixing and placing (including keying in) the mortar that will be used for the project onto the surface of the existing tile. Do this in several representative locations. Allow the mortar to cure for several days then remove it to determine how well it was able to bond to the substrate. You can select the trowel you will use for the job, comb the mortar and place a tile on top of the bond coat as a means of checking your coverage and inspecting the overall performance of the bond coat at the same time. Document everything about this test in writing and with photographs. Repeat the test with other materials and

tools if needed.
Depending on the results of the

bond test, it may be advisable to apply a primer that will facilitate bonding. Some setting-material manufacturers have specific primers designed for this purpose. They can recommend their best products (including mortar) for this application. I suggest using a system approach from one manufacturer that includes any primers, membranes, mortars, grouts, sealants, sealers, etc. I advise you to contact the technical representative of your preferred manufacturer about this job. They will be happy to assist you in writing a system warranty specific to this job.

Please also refer to ANSI A108.01 2.6.2.2 as an important reference for this installation.

It is necessary to ensure the substrate meets industry standard flatness requirements found in the ANSI Standards and TCNA Handbook. Please refer specifically to ANSI A108.01 2.6.2.2.

Generally speaking the standard is:

  • 1/4” in 10’ for tile with any side 
less than 15”
  • 1/8” in 10’ for tile with any side 
15’ or longer
  • Flatness can be checked with a 
10’ straight edge.

Financial allowances must be included in the specification, and proposal for labor and materials to flatten and otherwise prepare the substrate must be included in the specification and proposal. 
Tiling over sound existing tile as a substrate is an excellent way to proceed. As with any tile installation, careful research, proper planning, using the recommendations of industry standards, following manufacturer instructions, using a system approach, good communication and documentation before you proceed will mean a great and long-lasting installation and will make all parties happy with the end result. You are already on the right path. I hope this helps!

Mark Heinlein, NTCA Trainer/Presenter

Ask The Experts: July 2017

QUESTION:

I have a client with glass tiles cracking on an install. The GC admitted to not installing with a crack suppression membrane. They also drilled pilot holes for a door install that resulted in cracking. The tiles associated with the holes were installed before drilling. The final comment by the client was the cracking was from the back, and did not come through the face.

In your opinion, is it likely the lack of a crack isolation membrane created the opportunity for all of these tile cracks?

 

ANSWER: 

It appears to me that the crack at the window wall may be related to structural stresses within the framing or deflection in the substrate. The crack at the control valve may be related to structural stresses such as deflection within the substrate that was not well supported at the valve location. The cracks from the drill holes are likely related to the physical and heat stresses placed on the tile during the drilling process and may also be related to deflection in the substrate if the substrate was not well supported in this area. A crack isolation membrane would likely not have prevented the cracking.

There are other potential issues that can cause large-format glass tile to crack. They would include: Incorrect mortar or adhesive selection; mortar cure time (which will vary based on the mortar used and whether a waterproof membrane was used); thermal expansion from light or hot water; lack of expansion joints; deflection in the substrate; etc.
– Mark Heinlein,
NTCA technical trainer/presenter

QUESTION:

I’m dealing with customers who are unhappy about their recent tile installation. They feel the tile has too high a color variation. Could the installer have laid out the tile incorrectly? Whose responsibility is this – the installer’s, or mine? Thanks for your help.

ANSWER:

Per our conversation, on page 2 of the 2016 TCNA Handbook there is a section that deals with aesthetic classification. It specifically talks about variations in color, texture and appearance, and how tile suit- able for TCNA Handbook installations must meet specifications out- lined in ANSI 137.1. This ANSI standard sets performance and aesthetic criteria for many types of tile. Using tile that meets ANSI 137.1 ensures a degree of quality and consistency among tiles.

This chart from CTDA illustrates the ranking of shade variation levels, from the most uniformly shaded V1 to V4, which represents a tile with the highest degree of shade or color variation. A V0 tile is very uniform in appearance and smooth in color, with a color difference of less than 3 Judds when measured by a colorimetric spectrophotometer.

Tiles can have a V (variation) designation from V0 to V4. V0 tiles are very uniform in color and shade. V2, V3, V4 tile all increase in their randomness of color with V4 being the most random. Is the tile in question an ANSI 137.1 tile and what is its V designation?

The TCNA Handbook says that tile should be installed from several boxes in a random fashion to avoid aesthetic issues. Are you aware if the installer did this? How much was installed before the variations were noticed? How quickly did the installer report this to you?

It is common practice in our industry to report any defects or issues with the tile prior to installation. Many tile manufacturers even have disclaimers on their boxes explaining that claims against the tile must be made prior to installation. Let me know the answers to these questions and I will try to help you further.

– Robb Roderick,
NTCA technical trainer/presenter

 

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Ask the Experts – June 2017

QUESTION

I was on a walk-thru today and attached are photos of a chip on an installed tile wall at the World Trade Ctr.  There are numerous chips like this on the job from damage by other trades after we finished installing.

The architect is calling out these tiny chips on the punchlists and I’m arguing about with him considering the tiny size.

Sure we can remove and replace chipped tile, but I think there would be more of a mess than they might want to deal with.

Is there any criteria for this?  Like if a chip is less than  1/16” it stays?

Please let me know, and thanks in advance.

 

ANSWER

There are no criteria that I am aware of that states what size chip is acceptable.  It is extremely unfortunate when other trades do not respect our installations.  There is some debate as to whether it is a tile contractor’s responsibility to protect our work, or whether it falls to the trade that comes behind us to use a modicum of precaution and protection.  Perhaps you will be able to bill the contractor that damaged your work for your time to repair the damage they caused.

Please refer to these standards:

  • ANSI A108 is the Tile Industry Standard Specification for the Installation of Ceramic Tile.
  • ANSI A108.02 is the General Requirements for Materials, Environmental and Workmanship.
  • ANSI A108.02 4.3 is the section that discusses Workmanship, Cutting, Fitting and Grout Joint Size.
  • ANSI A108.02 4.3.3 states “Smooth cut edges. Install tile without jagged or flaked edges.”

Other tile industry standards include:

  • TCNA Handbook (2016 Edition)
  • ANSI A108 / A118 / A136 (Installation and Material Standards)
  • ANSI A137.1 (Ceramic Tile)

In addition, you will want to have:

  • ANSI A137.2 (Glass Tile)
  • A137.3 (Gauged Porcelain Tile / Panels – standard just approved at Coverings in April)

I hope to see you later this year when I am in the area.  – Mark Heinlein, NTCA technical trainer

QUESTION

I have a customer who wants wanted to use pebbles on the floor of the shower with grout joints washed really low. Are there standards or guidelines that relate to this type of installation that you can share with me?

ANSWER

The NTCA always encourages our members to use the standards and methods found in the TCNA Handbook for Ceramic, Glass and Stone Tile Installation, and the guidelines in The American National Standards Institute (ANSI).

In response to your question about the depth of grout in a grout joint: refer to ANSI 108.10 Installation of Grout in Tile Work.

In section 5.3.3 it states to “force a maximum amount of grout in the joint.” In section 5.3.4 it says, “All joints are to be uniformly finished.”

Part of the service we offer to members is technical support. We have in the past seen many instances where uncut pebbled stones have inhibited the flow of water in showers even with properly sloped assemblies, which in turn leave small puddles behind the stone affecting the uniformity of grout color. Also these small puddled areas — when not properly and regularly cleaned — can encourage mold growth when organic materials from soaps and shampoos are added to them. This is a significant enough problem that I’ve heard the 1/4 “per foot slope minimum requirements for shower floors may be changed to 1/2 “per foot slope to alleviate some of these issues. Not filling the joints full as directed by the ANSI standards previously cited could increase theses issues. – Robb Roderick, NTCA technical trainer

Low grout joints in a pebble shower floor go against standards and guidelines and can lead to problems. (Photo of correctly grouted pebbled floor courtesy of Stoneman Construction LLC).

Ask the Experts – May 2017

Several questions have been directed lately to our technical team concerning installing tile in elevators. Here are several responses:

QUESTION

I’m interested in installing tile on an elevator floor. Are there industry guidelines or standards for doing so? I have 3/4” of available depth to work with between the bottom of the elevator door and the floor.

ANSWER

There is no method for installation of tile on an elevator floor in our industry guidelines.

The elevator cabs chosen for some construction projects are not designed for tile or stone floor finishes. The manufacturer of these elevator cabs will list acceptable floor finishes, which 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 the most common elevator cabs that are not designed for it, 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 the warranties come strictly from the manufacturers.  – Robb Roderick, NTCA technical trainer/presenter 

We are not aware of any documents or standards but can offer you some cautionary advice. 

The majority of elevator floors are designed to carry a specific number of passengers or maximum weight load.  This design criterion focuses solely on how many people the car will carry rather than the stiffness or rigidity of the steel floor.  A flexing floor is not a good environment for a tile installation.  The fact that the architect is specifying a plywood underlayment may help, but unless the architect is willing to guarantee that this floor structure design will meet a MINIMUM of l/360, the risk for success will rest with you.

Some contractors have had success in getting approval from manufacturers to use their epoxies to install tile in elevators. Make sure you get their warranty and recommendation in writing.

You mentioned you had 3/4” of available depth.  When completed, the elevator floor must meet ADA guidelines.  This means that the finished floor must be flush with the adjacent sill or not exceed the maximum rise allowed within ADA regulations.  Most times the addition of the plywood would exceed  that allowance and be non-compliant.– NTCA technical trainers Mark Heinlein and Robb Roderick, with CTEF’s Scott Carothers

Ask the Experts

QUESTION

We had an issue recently with a White Thassos mosaic where the individual pieces on the sheet had inconsistencies in spacing on the mesh, with a few pieces exceeding a 2mm joint. The factory specification was made to a 1.5mm joint, but I’m told from our vendor that various factors (handling,

Thassos White Marble Mosaic

shipping, etc) can cause shifting to occur over time.

Can you confirm if there’s an industry standard tolerance for deviation on these types of mosaics? I’m sure the Marble Institute of America has something to this effect, but I don’t have access to their documentation to verify.

ANSWER

I am able to provide the specification for ceramic mosaic tile from ANSI A137.1.  Table 6 of ANSI A137.1 states the specifications for mosaic ceramic tile, including mounting/crooked tiles and for mounting/wide & narrow joints.  Those specifications are:

  • Mounting/Crooked Tiles:  Individual joint range <30% of the average joint width of the sheet.
  • Mounting/Wide & Narrow Joints:  Average joint widths for each tile must be within +/- 25% of the average joint width of the sheet.

ANSI A137.1 section 6.2.2.1.11 describes this a bit more:

The tile shall be uniformly mounted and in patterns specified.  Joints between tile shall be in accordance with manufacturer’s specifications.  For all mounted mosaics, the range of an individual grout joint shall be no more than 30% of the average joint width for the sheet.  For sheets containing mosaics of the same color, the individual average joint widths shall also be within +/- 25% of the average joint width for the sheet.  Sheets shall be accepted or rejected (for grout joint variations) based on the number of grout joints in the sheet.

As you stated, the manufacturer specification for the tile in this installation was for a nominal joint width of 1.5mm.  Some of the joints exceed 2mm.

When we apply the tolerance of <30% of the average joint width of the sheet for the mounting of Crooked Tiles, the acceptable narrowest part of the joint adjacent to a crooked tile would be 1.05mm.

When we apply the tolerance of +/- 25% for Wide & Narrow Joints the acceptable range becomes 1.125mm to 1.875mm.  2mm would be outside the range of tolerance.

Section 9.5 of ANSI A137.1 describes the laboratory testing method for variations in mounted mosaic ceramic tiles.  That is where we learn how many tiles and grout joints are to be examined and how many variations are acceptable based on the size of the individual tiles on the sheet and overall size of the sheet.  I am not certain if the specifications for stone mosaics are similar, but I am able to refer to the following.

In the Marble Institute of America’s “Q&A Manual (Expert Answers to Technical Questions About Working with Natural Stone)” the following is stated with regard for a reasonable tolerance for joint width:

“Tolerance is normally correct at a variation from true (specification) of 1/4 of the specified joint width. With a joint width of 3/32”, a tolerance of ± 1/32” is reasonable. A 3/32” joint is correct at 1/16” wide and at 1/8” wide. The joints should “eye up” straight and true. Be careful though, if the joint is specified at between X and Y.” *

To paraphrase the first sentence of the MIA’s statement, “a variation tolerance of 1/4 of the specified joint width” may be equivalent to +/- 25% for ceramic mosaics.

I have seen many instances where inadequate adhesive has been applied to the mesh allowing individual tiles to become loose or shift.  I have seen instances where the adhesive has dried out and allowed the individual tiles to become loose and shift on the sheet.  Many of these adhesives are water based; when they become damp they re-emulsify and lose their bond.  I personally have received a shipment of tile that had become damp at some point during the fabricating, mounting, packaging, shipping, storage and delivery process to such a degree that the mesh adhesive had lost most of its bond to the back of the tiles and the tiles themselves were mildewed.  I rejected that entire shipment.

When installing any type of mesh- mount mosaic, an installer should inspect each sheet for broken, loose or very inconsistently spaced tiles.  These should be cut off the mesh and individually placed or replaced.  Depending on the size of the installation, I always expect to repair at least several throughout the installation.

Some types of mesh used for mounting are less rigid than others.  Some mesh material used has thinner strands or larger spaces in the mesh fabric that make it flimsier.  This makes it more difficult for the installer to achieve consistent spacing when setting individual sheets and throughout the installation.

I hope this helps.  For more specific guidance, perhaps the Marble Institute of America would be willing to comment on your question. — Mark Heinlein, NTCA Technical Trainer / Presenter

* Quoted from Marble Institute of America “Q&A Manual (Expert Answers to Technical Questions About Working with Natural Stone)”  www.stonesofnorthamerica.com/technical/Expert_Answers_to_Technical_Questions_about_Working_with_Natural_Stone.pdf

Ask the Experts – March 2017

QUESTION

I have a school cafeteria with marble thresholds, all of which are broken. Is there something more stable that I can use to replace them? There are several:  3′, 4′ and up to 8’ lengths. Thanks.

ANSWER

While marble is among the softer natural stones, if the substrate is sound with no deflection and if the marble is properly bedded, it should hold up well.

As an alternative, I would suggest contacting a stone fabrication shop.  They often have remnant pieces of harder stone, Corian, or composite materials that they can mill to your specifications for length and width.  They can also put beveled or bullnose edges on them for you.  I have found that 2cm thick material works well for this sort of thing.

TCNA Handbook Method TR611-16 is your reference for more information and a schematic detail for proper installation of a threshold.

Any material you install will still require proper preparation of the substrate and proper bedding with appropriate mortar. —Mark Heinlein – CTI #1112 NTCA Technical Trainer / Presenter

QUESTION

Any chance you’ve seen discoloration on grout that’s brownish red? I have a few theories, but I honestly, never seen anything quite as grungy as the discoloration on this client’s shower.  

ANSWER

Sometimes mold that appears on grout is superficial and resides only on the surface of the installation. Most shampoos and soaps contain organic matter, some more than others .When you have organic materials temperatures and moisture, you have a great environment for mold to grow. Proper and regular cleaning of showers removes those materials. When used and not cleaned regularly you can end up with a “grungy” situation. Always use a neutral PH cleaners approved for cleaning the stone or tile in your shower. And always test them in an inconspicuous area to make sure you will have no adverse reactions. Double check for mold or wet areas outside the shower as well to ensure there are no leaks. If water has escaped the shower assembly and has reached the wood substructure this can also provide the organic matter needed for mold to grow. – Robb Roderick, NTCA Technical Trainer/Presenter

Ask the Experts – February 2017

QUESTION

I’m a homeowner in Berkeley, Calif. On my recently completed bath renovation, we’ve found that the shower curb collects water and it takes a long time to dry even with ventilation. I’m trying to determine if this condition meets industry standards or if it would legitimately be considered a defect. Someone online recommended NTCA may be able to provide help.

ANSWER

Thank you for contacting The National Tile Contractors Association. The TCNA Handbook’s wet area guidelines state that horizontal surfaces must be sloped to direct water to the drain. The slope recommended is no less than 1/4” per foot.

I couldn’t tell a whole lot from the picture you sent, but it appears there is metal endstop trimming out your curb. If that endstop edge is above the edge of the tile, it can sometimes act as a dam on curbs that are sloped. Many shower systems incorporate surface waterproofing that lays right under the tile and can be easily damaged by removing tile. I would suggest tiling over the existing curb tile using a chair rail or some type of specialty trim to maintain the integrity of the waterproofing below the surface. Guidelines for tiling over the existing tile are found in the renovation section of the TCNA Handbook in section TR711. Scarification or primers are sometimes needed. And always make sure to use the correct adhesive for tiling over tile in a wet area.

– Robb Roderick, NTCA trainer/presenter

QUESTION, part 2

Thank you very much for the prompt and helpful response! Much appreciate the advice to tile over rather than break tile and risk waterproofing damage.

You are right – there is a stainless steel edge on the curb; it seems to be proud and acting as a dam.

Regarding the tile-over repair – a question. The manufacturer says the 24” x 24” tile we are using is slightly bowed for water runoff. I suspect the current ponding is related to this. Can this type of tile be cut for successful use on a curb like this, and if so are there standards for how to do this correctly so the repair is successful?

ANSWER, part 2

The tile you have selected appears to be pretty typical as far as inherent warpage. A byproduct of the firing process in tile manufacturing is that tiles become bowed or warped. This normally manifests itself with the center of tile being the high point and the edges being the low points. There are ANSI standards for what is and is not allowable for warpage. Considering you purchased the material from a reputable manufacturer, I’m sure it would follow in the acceptable guidelines for warpage, since this company has a great track record of offering quality tile.

As far as doing the repair within standards, the requirements are for the existing installation to be sound, well bonded, and without cracks. All soap scum, wax, or coatings must be removed from the surface prior to installation. You may want to scarify or prime the surface of the tile prior to the installation to increase bond strength. Always select a mortar that is approved for tile-over-tile installations. Incorporate your 1/4” per foot minimum slope in the new assembly. Most curbs are 6” so this would equate to a minimum of 1/8” drop.

– Robb Roderick, NTCA trainer/presenter

Ask the Experts – January 2017

QUESTION

Attached are pictures of an exterior grout leaching problem we are having on concrete, waterproofed with a membrane with a latex-modified thinset mortar and sanded grout with additive. Latex leaching (or efflorescence?) came through the grout not long after installation.
We removed all the grout three weeks ago and covered with plastic as you can see. It never got wet for those three weeks and we had fans on the tile. Yet when a penknife was pulled through the joints, the material was still a little damp and the latex is still coming through.
We feel it is in the mortar we used. A manufacturer rep is supposed to look at it. The manufacturer said for us to use unsanded grout with an additive. I do not feel like that will work at all – the latex is leaching through, even with no grout in the joints.
We felt like an epoxy grout would be the answer to fix this. What is your professional opinion on this?

ANSWER

My suspicion is that this is latex migration coming from the mortar.
This does not necessarily mean it is a problem with the mortar itself. I suspect the latex in the mortar may not have been allowed to fully coalesce and may continue to be an issue. Have you lifted a tile to examine the coverage and condition of the bond coat?
It is good that you have asked the manufacturer for a review. They will be able to assist you in determining whether this is efflorescence or latex migration, and its source. If the residue is powdery and salty it is efflorescence. If it is hard and more difficult to remove it is likely latex migration.
It is important to solve the problem then select the grout. Trying to lock in the migration with epoxy grout is not necessarily a cure for the issue. The source of the efflorescence or latex migration must be determined then remedied to ensure a long term successful solution.
If epoxy is eventually selected as a grout, ensure it is rated for UV exposure on an exterior installation.
– Mark Heinlein
CTI #1112,
NTCA Technical Trainer/Presenter

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