Waterproofing for exterior balcony


I have a customer with an exterior balcony that is tiled on the floor and walls. The space below the balcony is conditioned space (front hall). The waterproofing has failed and he’s getting water in the room below when there’s rain. I don’t know what the existing waterproofing system is. He has asked me to remove and replace everything, but I’m not sure what kind of substrate/waterproofing to use. The rep of the company whose products I usually use tells me that they’re not approved for exterior use. The balcony has walls on four sides, so I need to be able to incorporate drains to let the water out. Is there a product that you can recommend for this application?


I am glad you have asked questions about this installation before proceeding. An exterior balcony over occupied space is among the most critical types of installations a tile contractor can face. There is very much information to consider, more than can be addressed here, so I will begin by listing the applicable reference material and asking you to take a look through the information listed below.

TCNA Handbook (2019 Edition)

  • Wet Areas Guidelines (Page 41)
  • Environmental Exposure Classifications (Page 44). See the definition for Res6 (Residential Exterior) and the charts for Floors and Walls on pages 46 and 47.
  • Methods for Exterior Roof/Deck and Balcony/Deck Floors: F103; F103B; F104; F105 (Pages 60 – 67).
  • Methods for Exterior Walls: W201 (Page 186); W202E (Page 188); W244E (Page 190)
  • EJ171 Movement Joint Guidelines for Ceramic, Glass, and Stone (Page 430)
  • Appendix B. Estimated Weights for Floor Installations (Page 444)

When reviewing the TCNA Handbook methods for Exterior Roof/Deck and Balcony/Deck Floors that I’ve listed above, please make note of this statement in the Preparation By Other Trades section: “Roof drains and membrane by other trades – provide completed drainage at roof membrane level by use of weep holes as shown or other methods.”

Regarding movement joints, please note of the Movement Joint section states: “…architect must specify type of joint and show location and details on drawings” and Method EJ171 states: “Because of the limitless conditions and structural systems on which tile can be installed, the design professional or engineer shall show the specific location and details of movement joints on project drawings.”

ANSI A108 / A118 / A136 (July 2019 Release date)

  • There are multiple sections in A108 and A118 that pertain to exterior and wet area installations, movement joints, thick bed system requirements, etc.

NTCA Reference Manual (2019/2020 Edition)

  • Prerequisites and Considerations for Successful Balconies, Courtyards, Patios, Plaza Decks, Roofs, Exterior Walking Surfaces and Swimming Pool Decks (Pages 156 – 157)

The section I’ve noted in the NTCA Reference Manual is extremely informational – please read it first. At the end of that section you will read this: “DISCLAIMER: The tile contractor is not responsible for the design of the system. To avoid potential liabilities use a general contractor and certified roofing contractor when waterproofing over occupied living space.”

There is no simple product recommendation or set of instructions or solution I can offer. The best advice I can give you is:

  • Follow the guidance of the NTCA Reference Manual and the TCNA Handbook, which recommend employing a general contractor, architect, structural engineer as needed to properly design and specify the structural support; mechanical (drainage) systems; movement/expansion details; waterproofing system and other elements of this very complex installation.
  • Hire a roofing contractor and mechanical contractor to install the primary roofing membrane and the mechanical/drain-waste-vent system.
  • Ensure considerations are made for any railings/balusters to not puncture the primary waterproofing layer unless they can be adequately sealed.
  • Ensure all of the waterproofing and membranes are flashed onto the walls and – since the walls are being tiled – are fully waterproofed or the water managed as outlined in the wall methods I’ve listed.
  • After the project has been engineered and designed by structural and mechanical professionals, contact and involve setting material and membrane manufacturers that will assist you in product selection and ask them to provide you detailed installation instructions for their products and a written system warranty that covers their products in this installation.
  • Follow all manufacturer instructions and guidelines in the TCNA Handbook, ANSI A108 and the NTCA Reference Manual.
  • Clearly communicate the complexity of this project to the homeowner and inform them what it will take to ensure their project is a success.

I hope this gets you started. After reviewing this information please contact me again with any questions you might still have and I will help as best I can. 

Who determines construction joints?


We are on a job won by a flooring contractor who will install sheet vinyl or porcelain tile on a concrete floor. We are trying to determine who identifies where the construction joints are and how they will be treated, if it is not provided in the drawings.


The person with knowledge of the building and structure has to identify where the joints are and how they will be honored or treated depending on the type of joint. 

If there are drawings and specifications for the job, the professional that analyzed the structure to ensure adequacy for a tile installation and who drew up the specifications is the person responsible for providing the tile installation contractor the drawings for location and identification of honoring / treating the structural joints.

You can refer them to TCNA Handbook method EJ-171 where this is further defined. 

Thin brick tips


Thin brick veneer is a popular option because of its light weight and cost.

I am bidding 10,000 to 12,000 square feet of thin brick. And I thought some advice would be prudent!

Would you care to share with me some of the tips and methods you put together? Any advice would be very much appreciated!


The NTCA Reference Manual has an upcoming white paper that deals with grouting thin brick; I will highlight some of those upcoming best practices.

If your project is in an interior dry location, then a standard grout (ANSI 118.6) or a Type S or N mortar may be acceptable, depending upon the environment it’s exposed to. (Please see the Environmental Exposure Classifications page in your TCNA Handbook).

However, since you have said that it is 10,000+ square feet, I am basing the following comments on the assumption that this project will be on an exterior wall location. When grouting thin brick in an exterior environment, installations using a standard cement grout (ANSI 118.6) or a Type S or N mortar have had their share of problems. These types of grout/mortars are easier to install using a grout bag with metal tips and they usually give the installer extended time to tool the joints. The problems are revealed when these installations are exposed to rain or freeze/thaw situations. These problems include the likelihood of efflorescence in wet areas and spalling in freeze/thaw applications. So for these reasons, standard cement grouts and mortars are not the “best” practice when it comes to grouting thin brick.

High-performance grout (ANSI118.7) is typically recommended by setting material manufacturers to minimize efflorescence and block water penetration into and through the grout. Installing these types of grouts has challenges, however, when they’re being used with typical wire cut (rough texture) thin brick.

These grouts usually use rapid-curing cement that gives the grout its high-performance characteristics, but these same qualities make them exceptionally difficult to clean from the face of the bricks. Additionally, the stiff texture and rapid setting of many high-performance grouts don’t lend themselves to being installed with a grout bag. If you soften the grout up by adding additional water to make bagging easier, you weaken the grout and it typically won’t stay in the joint, sagging onto the face of the brick, resulting in the problem you are trying to avoid by using a grout bag – getting grout on the face of the brick. Then you have to scrub the brick to try to clean it, many times resulting in low joints. 

Some contractors have found it helpful to use grout release (sometimes multiple coats are necessary), penetrating sealers, or even applying a sacrificial wax coating prior to installing the thin brick to reduce the absorption of the brick prior to grouting. 

However, each of these methods still has its own costs and challenges. Many will require an acidic type of cleaner and/or pressure washing. And the sacrificial wax coating will need to be removed after grouting and curing is complete by using a hot-water, high-pressure washer.

In view of these many challenges, it is always to your advantage to do a mock up prior to starting the job, as well as working with a setting material manufacturer and using its complete system (usually membrane, thinset, and grout), and consulting the thin brick manufacturer for its recommendations as well. Also ask your grout supplier if using one of their liquid admix products will give you the fluspeffy texture you’re looking for, since in certain grouts they’ve helped.

Some specifications for jobs that I have done require the grouting to be installed using a grout bag and others don’t. Therefore, some tile contractors qualify their bid to include their proposed method for installing the grout, joint treatment/tooling and cleaning method –including that while the face of the brick will be cleaned, the pits in the face of the brick may still contain some residual grout in them after final cleaning.

Hopefully this is some help, if you have any additional questions please feel free to email or call.

Thank you for your support of the NTCA.

Discoloration on shower grout


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.  


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 cleaner 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.

Efflorescence reappearing on stone floor


We just installed a stone tile shower floor. It was sealed twice and shortly after white stuff kept showing on the floor even though the walls of the shower and the bathroom are of the same tile. We then removed the sealant and re-sealed it. Again shortly after this white stuff comes out. I have used an efflorescence cleaner which removed it, but the white stuff keeps coming back. Can you tell me what is happening and how we can fix it?

Thank you in advance for all your help.


Without being there on site and doing several destructive tests to determine the actual cause of the problem, I can give you several of the most common causes for the condition that you have described. First of all, given the cleaning product you have described, it sounds like soluble-salt efflorescence. This soluble salt is a natural product that is present in the Portland cement-based products used most often to produce the setting bed that is under the tile installation and the grout material that is used to fill the grout joints.

Natural stone tile may contain these mineral salts as well, especially if the natural stone is a softer material such as marble or limestone. These mineral salts may, and most often do, migrate when exposed to water or water vapor. As a way to control or minimize this efflorescence, water management is of the utmost importance. Careful consideration of the materials being used should be taken into account. Efflorescence that occurs after the tile or stone installation is in service is very difficult to stop or even control. Time and use will eventually cause all the “free mineral salts” to be exhausted and the problem will go away, but to fix this problem from the beginning will most likely require a removal of the entire shower floor, and may even require removal of portions of the walls or all the walls as well.

Starting fresh with a new shower framed and ready for tile or natural stone, the methods for proper shower assemblies can be found in the TCNA Handbook for Ceramic, Glass and Stone Tile Installation. These methods show pre-sloped shower pan assemblies, weep hole protectors, references to American National Standards Institute (ANSI) for proper mixes and measures for setting beds such as 1-to-4-ratio of Portland cement to washed masonry sand used in many shower pan assemblies. The TCNA list cautions when using soft natural stone products in wet areas – if efflorescence may be of concern – a porcelain or ceramic tile that is made to resemble natural stone may be a safer choice.

A few things the NTCA Reference Manual has to say about the causes efflorescence are as follows:

  • Soluble salts from the Portland cement-based products brought to the surface by capillary action where there is water or moisture present.
  • Contaminated water or sand containing soluble salts.
  • Excessive mineral content in the water used for maintenance.

Is there a method for moving a construction joint using anti-fracture membrane?


I have a small floor install in a basement. A construction joint runs about 1/3 into my floor. I’m installing 6”x36” porcelain tiles over this floor. My plan was to create a soft joint in line with the construction joint. 

Two problems exist with this joint. 

1. It’s out of square 3/4 to the adjacent walls. 

2. If I lay out with full tiles on both sides of where the construction joint is located, I end up with a 1” strip on one of the adjacent walls. 

I was under the impression there is a method for moving the joint using anti-fracture membranes, etc. Whatever the case, would you please advise me as to what would be the best practice based on the situation I described?


Thanks for your question. This is a common concern and I am glad you are addressing it before installing the tile.

Manufacturers of crack-isolation membranes will sometimes allow that one or more products are capable of spanning a construction joint in the substrate. This is a case-by-case, product-by-product, manufacturer-by-manufacturer consideration, since many products have similar properties but different limitations. I suggest you contact your go-to membrane manufacturer and ask which of their products might be suitable for this application and what their instructions are for applying it. Their Technical Data Sheet and Installation Instructions will be very informational.

IMPORTANT NOTE: Membranes designed for crack isolation are only appropriate for in-plane (lateral/side-to-side) movement. They are not appropriate for out-of-plane (up and down) movement of the substrate. If one or both of the sections of substrate that have been isolated from each other move up or down, the membrane likely won’t be able to protect the tile. Crack-isolation membranes have limitations for how much side-to-side movement they can handle. This varies from product to product.

In addition to EJ-171, the TCNA Handbook has two methods for crack isolation (Full Isolation and Partial Isolation). Please use the Method Locator in the back of the Handbook to find these methods. They will provide you with more information. 

– Mark Heinlein, NTCA Training Director

Lighting is causing wall-washing effect


I wonder if you can help me out on a problem we are having based on coved lighting that causes the wall-washing effect.

We have a project we did a year ago where we installed 3” x 6” wall tile at the restroom walls; at the wet walls there is coved lighting. When they turn on the lights, the installation looks horrible at the walls with the light cove. Do you have any information about light placement, and what is the allowable variance in the actual tile-to-tile installation, and also information how to resolve this besides tearing out the walls? Thank you! 


In Chapter 6 of the NTCA Reference Manual there is a section called Critical Lighting, as well as a Lighting and Tile Installations section in the TCNA Handbook for Ceramic, Glass and Stone Tile Installation. They both address this problem. There are also standards in both TCNA and ANSI about allowable lippage. For the tile and grout joint size you are using in this installation, the allowable lippage is 1/32″, which is about the thickness of a credit card.

The sections about lighting explain how installations that meet industry standards for lippage can look poorly under these lighting conditions. Some installers in the same situation will turn off the lights and put a different light source on at a different angle on the same wall. They then document both lighting situations with photos, showing this to their customers to explain the effect light can have on the appearance of the installation. I would check to make sure the installation is in tolerance for lippage. Then, I would take the NTCA Reference Manual and TCNA Handbook to your customer showing them what our industry says about this type of lighting. I hope this helps.

Robb Roderick, NTCA Technical Trainer

Do the typical TCNA standards for expansion joints pertain to GPTP too?


I wonder if I could get some advice from you for this project that we are to start installing in a few weeks. It is a medical office building in San Diego, using large-format porcelain tiles in the nominal size of 30” x 60” x 1/4” thick. The floor is a concrete slab that we are going to install using the thin-set method, and there are some control joints in the slab. We have roll-on liquid crack isolation and will be installing the tile with a crack-prevention mortar. 

My question for you is: Do the typical TCNA standards for expansion joints pertain? In reading literature from a different manufacturer on their thin porcelain slabs, they list 20’-0” o.c. for expansion. And how would you handle control joints in an installation where they will not fall on a grout joint and we are using a roll-on crack-isolation membrane? We have about 7,000 sq. ft. of this flooring.


The answer is yes. The ANSI Standards and TCNA Methods for expansion, movement, change in plane joints, honoring control and contraction joints etc., do pertain to that type of tile, which is known as Gauged Porcelain Tile/Panels/Slabs (GPTPS).

ANSI A108.19 is the installation standard/instructions for GPTPS. Section 18 of this standard refers to the ANSI A108 standard for expansion joints and TCNA Handbook Method EJ-171.

Requirements for placement of the joints, width of the joints and material used to fill the joints are detailed in the standards and in TCNA EJ-171. It is very important to understand that it is the job of the design professional or engineer to specify the placement and width of all joints in the design drawings and specifications. Their calculations for placement will include consideration for substrates subject to deflection, shrinkage, and expansion, etc.

I strongly encourage you to contact the tile manufacturer to ensure their tile is rated for a floor installation. Some GPTP manufacturers have different types and thicknesses of tile, some of which are recommended for wall installations only.

When using any crack-isolation membranes – and especially when using a liquid membrane – it is extremely important for you to:

Ensure the membrane is installed exactly as required by the membrane manufacturer’s instructions. This includes preparation of the substrate, number of coats to be applied, wet film thickness of each coat, cure time, etc.

Contact the membrane manufacturer and request from them the specific requirements for their membrane to bridge control joints. Ask them for a job specific warranty for this installation.

Have you attended a GPTP installation course? 

When to use moisture-resistant gyp-board or cement board


I’m writing with a question that I hope you can either answer or point me to the best resource that would be able to provide some insight.  

We’re doing architectural work for a national chain restaurant and I’d like to confirm that we’re using the appropriate backer board for tile walls. The question is: moisture-resistant gyp-board or cement board?

We use wall tile in food prep areas and restrooms. The walls get wiped down and might get splashed with water, but they don’t get hosed down or soaked.  

Let me know if there’s a simple rule when cement board should be used, as opposed to moisture-resistant gyp, or if there’s a reference standard that would shed some light on this question (I already tried the TCNA Handbook).


Thank you for contacting the National Tile Contractors Association. Industry-recognized wall tile installations are found in the TCNA Handbook

Two methods that use gypsum board are method W242 and W243. In the Environmental Exposure Classification section of each method it notes that they are appropriately used in Residential 1 or Commercial 1 type installations. Commercial 1 areas are described in the Environmental Exposure Classification of the TCNA Handbook as tile surfaces that will not be exposed to moisture except for cleaning and gives examples  such as: floors in areas with no direct access to the outdoors and no wet utility functions; hallways; dry area ceilings; soffits, decorative/accent walls; and corridor walls.

Commercial 2 is described as surfaces that are subject to moisture but do not get soaked or saturated due to system design or time exposure. Examples of Commercial 2 installations are: floors in bathrooms and locker rooms; some backsplashes and other walls such as bathroom walls and wainscot where water exposure is limited and or water is removed. Commercial 3 is described as areas that are soaked, saturated, or regularly and frequently subjected to moisture or liquids. It also lists some commercial kitchen walls.

Method W244 uses cement backer board in the installation and is suitable for Commercial 1,2, and 5 installation. 

Repairing Saltillo tile


I got a call today from a customer who chipped her Saltillo tile and wants to know if it can be repaired. The tile actually has many chips and imperfections, but these particular chips took the outer glaze or sealer off of them, exposing the raw clay. Could I go over the open spots with a high-gloss sealer and close them up? Any ideas or guidance would be greatly appreciated.


Depending on the depth of the chip, the application of a high gloss sealer could work. One important component when using sealers over pre-sealed tile is to make sure that the sealers are compatible with each other. Whenever two sealers are not compatible, it can leave a white cloudy appearance on the tile that is difficult and sometimes impossible to remove. So always do a test area in an inconspicuous place like a closet or behind a refrigerator. If you can identify what was used originally to seal the floor, it would be ideal to use that product. Many times changing the color of the clay underbody that is visible in the chipped area by sealing makes the chip virtually disappear. I hope this helps. 

– Robb Roderick, NTCA Technical Trainer

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