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

Tips for Successful Floor & Wall Tile Installation With No Lippage

Many contractors contact NTCA technical advisers regarding acceptable tolerances for floor tile installations, but our trainers also tell us that with the increased use of large format tile being specified for walls, it is becoming increasingly challenging for tile contractors to successfully install these products without lippage. Contractors should be aware that the tolerances for both floors and walls are the same, and that this issue should be addressed before installing the tile.  Many applications in dry areas are to be installed directly over gypsum board or drywall, and there is little opportunity with the adhesive to make up for imperfections in the surface. Lighting can also wreak havoc on a tile installation on a wall, making the edges appear to be even more uneven and imperfect. Industry tolerances for both floor and wall tile applications state that the substrate should have a maximum variation of /14” in 10’ from the required plane, nor more than 1/16” in 12” when measured from the high points in the surface.  If a builder wants a tile installation to be flush with no or minimal lippage, they need to make sure the framing and drywall contractors are delivering a surface that meets tile industry tolerances.  If the tile contractor doesn’t check for this, and accepts the substrate as is, they run the risk of having a serious issue take place that can cost everyone money and time.  

For more information on this subject, you can order the TCNA Handbook or ANSI A108 Book for tile installation on the NTCA website at www.tile-assn.com

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

NTCA Technical Trainer Robb Roderick on Tile Installation in Elevators

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 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 the warranties come strictly from the manufacturers.

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

Ask the Experts – December 2016

SponsoredbyLaticreteQUESTION

We have a contractor who used two different tiles. He bought the 4” x 4” tile elsewhere but after installation it appears to have changed color. The tile he bought from another source at the bottom, stayed looking like it did prior to installation. What could have caused this?

ANSWER

glazed-wall-tile-ateThe color of some tiles can change with grouting, for example this can occur with soft, natural stones and unglazed, honed or polished through-body ceramic/porcelain or quarry tiles (and/or if grout release wasn’t used).

It appears the tiles shown in this installation are glazed ceramic. You stated the two sizes of tile were procured from two different distributors. It is possible that even if the tiles are from the same manufacturer they may have been manufactured on different dates or in different lots. That being the case, the glaze may have a slight variation between the two. The glaze also appears to be different on the bullnose tile.

If spare, uninstalled 4” x 4” and 3” x 6” tiles from this job, new from their cartons, are placed side by side, I suspect you may notice the difference in color between them. Have you checked to see if the two tiles are from the same manufacturer and what their date of manufacture and manufacturer lot numbers are? This information should be available on the end flaps of the tile cartons. If the manufacturer, date of manufacture or lot numbers differ, there may well have been a difference in glaze color out of the box that wasn’t noticed until the tiles were installed and grouted

It is important to verify that all of this information aligns between all cartons of tile before beginning the installation.

Mark Heinlein – CTI #1112, NTCA Technical Trainer/Presenter

QUESTION

I need to know what the TCNA standard for slope in a commercial kitchen is.

ANSWER

The minimum slope for floor drains is 1/4” as specified by ANSI A108.01 2.2, which directs compliance with ANSI A112.21. The Universal Plumbing Code also specifies minimum slope of 1/4” per 12”.

The mortar bed is to be of a uniform thickness. ANSI A108.01 2.6.1.4 and 2.6.1.5 include a chart and discussion of minimum and maximum mortar bed thicknesses based on the service rating of the floor. For a commercial kitchen rated as Extra Heavy/Heavy, the bed thickness is 2-1/2” minimum to 3-1/2” maximum. Appropriate size and gauge galvanized welded wire mesh (i.e. 2” x 2” 16 gauge) must be suspended as reinforcing wire in the mortar bed. If the mortar bed will be in excess of 3-1/2” thick, heavier reinforcing, larger aggregate, richer mix and greater compaction may be required and must be detailed by the specifier.

To keep the mortar bed from becoming too thick or the slopes to a drain too long, multiple drain locations should be planned based on the layout of the kitchen.

Mark Heinlein – CTI #1112, NTCA Technical Trainer/Presenter

Ask the Experts – November 2016

SponsoredbyLaticreteOne of the benefits NTCA offers is its technical staff, and seasoned know-how that can be tapped to address problems and questions. Here’s an example of the profusion of information from the NTCA technical staff for the questions of one Hawaiian homeowner. – Lesley Goddin

QUESTION:

I am a homeowner in Hawaii looking at installing a large-format porcelain tile floor (planks are ~9” x ~47”). I have two questions.

My first question is what is the NTCA convention for pricing that tile install? Is the convention for an install price per square foot based on the actual footprint of the rooms (actual tile on floor when job is done) or does it also apply to the tile waste?

As an example:

– Lets say I have a simple 25’ x 40’ room: 1,000 sq. ft., once the tile is installed.

– Lets say I plan on 10% waste. So I purchase 1,100 sq. ft. of tile

Would your convention for the installers bid price be X dollars per sq. ft. based on the 1,000 sq. ft. or based on the 1,100 sq. ft.?

My second question is what sort of waste percent should I expect for that large-format 9” x 47” tile?

Thank you for your time and feedback.

plank-tile-ateANSWERS

We have three technical trainers on staff, and they are all coming off of extensive travel dates for training programs, so I am taking a shot here on this question, and they will likely provide additional or a slightly varied response.

In my experience on this subject, the labor bid for the job generally covers the 1,000 actual square footage of the room in the bid. However, if you have a 10% waste factor for materials, you would be charged for the 1,100 sq. ft. of material. My customers usually ordered about 3-5% in a straight-cut square pattern and 7-10% with a pattern design, like what you are describing below. This depended on room size and how it is laid out. I will see if they chime in with a different response but this has been my experience in the past.

Bart Bettiga, 

NTCA executive director

Bart has provided you correct information. I would add that with a plank tile such as your 9” x 47,” I may consider estimating upwards toward 12% depending on the pattern, obstacles, squareness of the room(s), etc. This is especially critical for special-order material to ensure it is all from the same manufacturing lot. Any remaining tile should be retained as “attic stock.”

There is not a standard pricing convention for labor. A contractor may base the labor rate on square footage, hourly or daily rates. A qualified contractor using Certified Tile Installers will be very familiar with the intricacies of installing large-format tile. Large tile is not necessarily faster or easier or less expensive to install. Additional substrate preparation is almost always required to ensure a quality installation based on tile industry standards.

The NTCA does have member contractors in Hawaii. Please search for them on our web site at: http://www.tile-assn.com/search/custom.asp?id=2759

To locate a Certified Tile Installer please search the Ceramic Tile Education Foundation at: https://www.ceramictilefoundation.org/find-certified-tile-installers

I hope this helps.

Mark Heinlein – CTI #1112, NTCA trainer/presenter

In my area, most installers are paid for the amount of material they use rather than the square footage that they cover. They do have to handle, cut, and dispose of that tile and usually will include it in their invoice.

As far as percentage waste to figure, two things should be considered: the layout of the area and the pattern to be installed. One single square room usually requires very little waste, while an installation with many corridor and rooms would require more.  Also a straight-lay pattern requires very little waste, while a herringbone pattern or an installation on a 45-degree would require much more. I figure somewhere between 5 and 15% waste considering all the factors just mentioned.

On a commercial project, the spec book often times calls for 5% attic stock to be left on site at completion. If that’s the case you would also want to add that on to your estimated waste amounts.

Robb Roderick, NTCA trainer/presenter

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