Tag Archives: Ceramic tile

Specifying the Right Grout for the Job

All images courtesy Custom Building Products

All images courtesy Custom Building Products

by Steve Taylor 

Specifiers typically select grout for tile projects based on general performance characteristics, color, warranty, and cost. However, less-than-optimal products are often used. Some design professionals are unaware of the changes in technology, not realizing all grout is not the same. Color and aesthetics are only one small factor in the product’s overall performance.

Specifiers and designers should evaluate each ceramic and natural stone tile project and base the grout decision on the function as well as appearance of the space to be tiled. Some grout perform well in certain situations, while others will fail when not specified correctly.

Before selecting a grout, some questions to consider about the area and installation are:

  • Is it a lightly trafficked office foyer or a mall food court installation, with heavy traffic and exposure to a tough cleaning regimen?
  • Is the tile project likely to be soiled with foods (i.e. from commercial kitchens or food-processing) that can stain the grout? What about caustic materials (i.e. acids or alkalis) from factories that will deteriorate standard grouts, or harsh cleaning chemicals that may damage the grout?
  • How soon will the tiled area be opened to service and traffic?
  • Is this a remodel that must be returned to service the next day?

Further, there are many colors from which to choose and, therefore, many choices of grout based on different chemical technologies to address these concerns and help achieve a durable and aesthetically pleasing tile installation.

Grout background

An understanding of grout is necessary to make educated choices. Traditionally, grout was based on the same technology as bonding mortar—portland cement and sand. Installers were accustomed to using sand and portland cement blends for installing tile and filling joints between tiles. Today, these cement-based tile grouts are divided into two categories: standard cement grout and high-performance.

Standard cement grout for tile installation

This type of grout meets the requirements of American National Standards Institute (ANSI) A118.6, Specifications for Standard Cement Grouts for Tile Installation, which establishes the performance of basic polymer-modified and non-modified portland cement grouts. These grouts can contain sand for filling joints greater than 3.17 mm (1/8 in.) or be non-sanded for joints that are less than 3.17 mm wide. ANSI A118.6 establishes minimum performance levels for compressive strength, flexural strength, shrinkage, and water absorption. These have been commonly used in the industry for 50 years.

Knowing the surface and what it will have to sustain is important in selecting grout. Specifiers should evaluate each ceramic and natural stone tile project and base the grout decision on the space’s function.

Knowing the surface and what it will have to sustain is important in selecting grout. Specifiers should evaluate each ceramic and natural stone tile project and base the grout decision on the space’s function.

High-performance cement grout for tile installation

Meeting the performance requirements of ANSI A118.7, Specifications for High-performance Cement Grouts for Tile Installation, a grout is generally polymer-modified to reduce water absorption from 10 percent (i.e. standard grout) to less than five percent. This is important, since staining of the grout is more likely with more absorbent material. Tensile and flexural strength are both increased in these grouts. This results in higher durability. As these high-performance grouts are highly modified, it allows the manufacturer to add other benefits such as quicker curing, reduced shading, and efflorescence control.

The advent of high-performance cement grout with modern technology has eliminated many of the concerns installers have with the standard cement grout. In many cases, these high-performance grouts are necessary to complement advances in ceramic tile technology.

It is generally accepted by the ceramic tile industry the lifecycle of a ceramic tile installation is 60 years. High-performance cement grout has high strength and a hard finish like the surrounding tile. When these installations are properly sealed and maintained, they will hold up for the life of the tile installation. However, if they are not properly maintained and cleaned, acids from contaminants and cleaning agents will break down the grout’s portland cement component and weaken its internal structure. After a few years, the affected grout in the joints will sufficiently degrade and have to be replaced. This problem with cement-based grouts led to the development of chemical-resistant grouts.

Chemical-resistant grouts

The first chemical-resistant grouts were based on epoxy resin because it could be easily mixed at the jobsite and cure at the same rate as the traditional cement-based grout. Epoxy resists many chemicals, such as solvents and strong acids, and can be easily pigmented in factories to produce an array of colors. Factory-controlled coloring of the epoxy allowed manufacturers to produce a more consistent batch-to-batch appearance.

There are many choices of grout, based on different chemical technologies, to address concerns of achieving a durable and aesthetically pleasing tile installation.

There are many choices of grout, based on different chemical technologies, to address concerns of achieving a durable and aesthetically pleasing tile installation.

The curing of portland cement based grout relies on the hydration of the portland cement to build strength. The amount of hydration also affects the color/shade of the grout. Fully hydrated portland cement grouts tend to be lighter in color than the partially hydrated cement. If the grout is not uniformly hydrated, it will show shading (i.e. light and dark areas) across the tile installation. Higher performance grouts have been developed to address shading. The curing of the epoxy does not affect the color, so the appearance throughout the installation remains uniform throughout the curing process.

Standards were developed to classify the epoxy resin-based grouts into two categories: chemical-resistant, water-cleanable tile-setting and grouting epoxy, and modified epoxy emulsion mortar/grout.

Chemical resistant, water cleanable tile-setting and grouting epoxy meeting the requirements of ANSI A118.3, Specifications for Chemical-resistant, Water-cleanable Tile-setting and Grouting Epoxy and Water-cleanable Tile-setting Epoxy Adhesive, was established as a minimum performance requirement for water-washable 100 percent solids epoxy grout.

Modified epoxy emulsion mortar/grout with performance meeting ANSI A118.8, Specifications for Modified Epoxy Emulsion Mortar/Grout, is available for addition to standard cement grout. The modified epoxy emulsion grout was developed to be mixed with traditional cement-based grout in place of water. While this improved the strength and stain resistance of the standard cement grout, it did not completely eliminate its chemical sensitivity. Today, this grout type is not commonly found for sale.

Replacing the portland cement binder with epoxy resin made the original ANSI A118.3 epoxy grouts hard to install and spread across the face of the tile. Installers found it difficult to clean during the installation. This resulted in additional labor cost and a less-than-acceptable looking tile installation.

Over the years, there have been many advances in the chemistry of epoxy resins. Manufacturers of epoxy grouts have taken advantage of these chemical breakthroughs and develop 100 percent solid epoxy grouts meeting the requirements of ANSI A118.3.

Many grout choices depend on location, among other things, to achieve a durable installation.

Many grout choices depend on location, among other things, to achieve a durable installation.

These grouts were formulated for easy spreading and filling of the joints in tile assemblies. They contain non-sag and non-slump properties, allowing installers to fully fill joints on both horizontal and vertical surfaces. Further, they are designed to clean off the tile’s surface during installation. They are also chemical-resistant and suitable for commercial installation. While epoxy grout fills the need for chemical resistance in most installations, some industrial applications need even greater resistance to harsh chemicals.

The need for even more chemical- and heat-resistant materials in industrial applications resulted in the development of less-common furan resin-based grout. Chemical-resistant furan mortars and grouts meet the performance characteristics of ANSI A118.5, Specifications for Chemical Resistant Furan Mortars and Grouts for Tile Installation, unfortunately, when these grouts are installed they cannot be removed from the face of the tile with ordinary water. The installer must use solvents, like alcohol, to remove excessive grout form the face of the tile and his tools.

Installation of furan resin grout requires special techniques, including the coating of the tile with wax. Besides having extremely good chemical resistance, furan resin is known to produce a high bond to ceramic surfaces. To prevent permanently bonding to the face of tile, the tile face must be coated with wax that has to be removed once the grout is fully cured. Due to the difficulty in installation, furan-based grouts are used in areas demanding the highest resistance to chemicals (i.e. battery manufacturer that use strong acids).

Manufacturers of maintenance cleaners continue to improve products, making them more effective and easier to use. The latest developments in cleaners include agents to help break down the common greases that end up on floors of commercial kitchens caused by deep fryers. When these greases break down by the action of the cleaner, they convert an organic acid (i.e. fatty acid) detrimental to the grout and should be removed from the surface. These acids are aggressive on cement grouts and normal epoxy grouts; if left in contact with the grout for extended periods, they will begin to break down the epoxy resin in the grout.

Furan grout has a higher chemical resistance to the organic acids and would be a good choice for commercial kitchens. However, the expense and difficulty in installation make them less attractive to the installer. Recently grout manufacturers have developed improved 100 percent solids epoxy grouts meeting the performance of an ANSI A118.5. These grouts are easier to install, with the same characteristics of an ANSI A118.3 epoxy grout, but have higher chemical and temperature resistance. They will hold up to the latest commercial cleaners for 15 to 20 years in commercial kitchens. While these epoxy grouts do have an industry standard, they are labeled by their manufacturer as industrial-grade epoxy grout meeting the performance of ANSI A118.3 and A118.5.

The latest development in grout for the installation of ceramic and natural stone tile is single-component, ready-to-use, and premixed. These grouts are water-based and use polyurethane, acrylic polymer, and/or silicone resin for the binder, in place of portland cement or epoxy. Industry standards have not yet been developed for these grouts, so there are many performance differences between them. It is important to confirm with the manufacturer this type of grout is suitable for the particular installation; some are suitable for wet areas and others are not.

Design professionals need to be aware of the changes in grout technology. Color and aesthetics are only small factors in the product's overall performance.

Design professionals need to be aware of the changes in grout technology. Color and aesthetics are only small factors in the product’s overall performance.

The most recent developments produced grouts with many of the desirable properties of portland cement grout and 100 percent epoxy grout. They are easy to install, cure rapidly, and have chemical resistance of an epoxy grout. Some are the most stain-resistant grouts on the market and never have to be sealed to prevent being stained.

Conclusion

There are many choices in finishes for the architect, specifier, and designer to choose from. When it comes to selection of ceramic tile one should not overlook the grout. It is important to select a color of grout that complements and works with the project; it is equally important to select the right type of grout to meet the function of the tiled area. The majority of the projects will only require a standard or high-performance cement grout.

Today, there are a growing number of areas, like commercial kitchens, where ceramic tile is used and would greatly benefit from an industrial grade of epoxy. One should not overlook the up-and-coming single-component grout in many installations. The various types of grout available have been discussed, and it should be easy to specify the right type with the correct ANSI standard identification. Many suppliers have grouts performing above the standards—in these cases, it is important to specify a performance level in addition to the minimum ANSI standard. Following these guidelines helps ensure a long-lasting, attractive ceramic tile installation.

Steve Taylor is director of architecture and technical marketing for Custom Building Products. He has more than 30 years of experience developing products for the construction industry. A member of Tile Council of North America (TCNA) and Materials & Methods Standards Association (MMSA), he helps determine proper tile installation methods and standards. Taylor can be reached by e-mail at stevet@cbpmail.net.

Specifying Movement Joints and Sealants for Tile and Stone: Reviewing current industry standards and design options

Photo courtesy Florida Tile

Photo courtesy Florida Tile

by Donato Pompo, CTC, CSI, CDT, MBA

In one way or another, all tile and stone assemblies move. Whether due to thermal or moisture movement, shrinkage, freezing, or dynamic structural movements, tile and stone installations are subjected to them all. To ensure a long-lasting installation, architects must specify the requirements for movement joint design and placement, along with the correct type of sealant for filling those joints.

A ‘movement joint’ is a general term used for all types of joints seen in construction materials that control and allow movement. Most commonly, they are known as ‘expansion’ or ‘control’ joints, but there are various categories. Generally, they contain an appropriate pliable sealant for the intended application, which is often referred to as a ‘soft’ joint.

Movement joints allow for the material in which they are placed to move without restraint; they control where the movement manifests to avoid random cracking in finish materials. An example would be the joints or separations in a concrete sidewalk. If there were no movement joints in the concrete sidewalk, then it would crack at a random point as it is subjected to shrinkage during curing, or to expansion when it is exposed to moisture (and then contraction again as it dries). Rising temperatures cause expansion, lowering temperatures cause contraction, and wet freezing conditions cause both, as the temperature drops and the moisture freezes.

There are other types of structural movement from the ground or its foundation that can cause various kinds of movement in the form of deflection. These stresses, and the resulting deformations, are compounded by adjacent materials that have a different coefficient of movement properties—the differentials can lead to serious problems, particularly over time as the respective materials go through various degrees and combinations of cycles from wet to dry or hot to cold, and so forth. Movement joints are also designed to isolate different materials from each other so they do not affect adjacent materials.

More often than not, when there is a tile (e.g. ceramic, porcelain, stone, or glass) failure a contributing factor is the lack of properly installed movement joints. In some cases the failure could have been avoided, or damage limited, if there had been properly installed movement joints. Just like concrete sidewalks, slabs, and bridges, tile and stone need to have movement joints to control the anticipated movements within a structure and the various climatic conditions it will be subjected to throughout the years.

Small horizontal movements can result in exponentially larger vertical movements. When one end of a ruler is restrained and the other end moved toward the center 3.2 mm (1/8 in.), there is a 51-mm (2-in.) rise at its apex. Photos courtesy Ceramic Tile and Stone Consultants

Small horizontal movements can result in exponentially larger vertical movements. When one end of a ruler is restrained and the other end moved toward the center 3.2 mm (1/8 in.), there is a 51-mm (2-in.) rise at its apex. Photos courtesy Ceramic Tile and Stone Consultants

Figure1b

Troubles with tile and stone
This author has seen tile floors that did not have adequate movement joints—where a portion of the floor was tented (i.e. debonded and raised) several inches off its substrate during the heat of the day, but was lying flat at night when it cooled down. For a good example of how small horizontal movements can result in exponentially larger vertical movements, one can take a 1219-mm (48-in.) metal ruler and lay it on a horizontal surface. When one end of the ruler is restrained and the other end moved toward the center 3.2 mm (1/8 in.), there is a 51-mm (2-in.) rise at its apex. In effect, this is what happens to tile floors when they tent. They are constrained at their perimeters with no movement relief, the tile is typically insufficiently bonded, and it expands for one reason or another.

Well-bonded tile floors tend to crack to relieve the stress rather than lose their hold. Properly placed movement joints allow the tile to move and control where the movement manifests (i.e. within the joint where the tile is not restrained).

Tile and stone installers may have practiced their trade and honed their skills, but they are not engineers. In other words, while installers have some responsibility in ensuring movement joints are included in the tilework, it is ultimately up to the architect to specify the appropriate design, materials, and locations.

The Tile Council of North America (TCNA) provides general movement joint guidelines for tile and stone applications in its TCNA Handbook for Ceramic, Glass, and Stone Tile Installation, listed under Detail EJ171, “Movement Joint Guidelines for Ceramic, Glass, and Stone.” TCNA states:

because of the limitless conditions and structural systems on which tile can be installed, the architect or designer shall show the specific locations and details of movement joints on project drawings.

There are industry standards that help design the appropriate movement joint layout and design for the intended application:

  • ASTM C1193, Standard Guide for the Use of Joint Sealants, which provides guidelines on how to use and install sealant joints; and
  • ASTM C1472, Standard Guide for Calculating Movement and Other Effects When Establishing Sealant Joint Width, for determining appropriate movement joint width relative to the intended application and conditions.
These two photos of the same spot show what happens when transition joints are fi lled with a hard grout rather than the soft movement joint sealant. The cementitious grout and stone crack due to expected movements within the stone and the structure. It is a good example of why we need movement joints in tilework.

These two photos of the same spot show what happens when transition joints are filled with a hard grout rather than the soft movement joint sealant. The cementitious grout and stone crack due to expected movements within the stone and the structure. It is a good example of why we need movement joints in tilework.

2CrackedGroutDueToMissingTransitionMovemtJoint

Ensuring adequate design
The appropriate design of a movement joint is based on the tile assembly’s configuration and substrate type. The substrate must be structurally sound, meet relevant code requirements, and not exceed maximum deflection limitations (ranging from L/360 to L/720, depending on the material and the application). The general rule is these movement joints should be placed at the perimeters of tile and stone installations, at all transitions of planes or different materials, and within the field of tile.

Tiles at perimeters of rooms should have movement joints. Inside and outside vertical joints on framed walls should have movement joints and not be hard-grouted (as they so commonly are, alas). Bathtub or shower receptor to wall transitions should have a movement joint. In wet areas, movement joints are important not only to control movement, but also to act as a water-stop at those transitions, providing another layer of protection.

Whether due to thermal or moisture movement, shrinkage, freezing, or dynamic structural movements, all exterior stone assemblies—like this limestone fountain surrounded with granite paving—are going to move.

Whether due to thermal or moisture movement,  shrinkage, freezing, or dynamic structural movements, all exterior stone assemblies—like this limestone fountain surrounded with granite paving—are going to move.

TCNA states movement joints for interior applications should be placed at least every 6.1 to 7.6 m (20 to 25 ft) in each direction unless the tilework is exposed to direct sunlight or moisture, which would then require the movement joints placed at least every 2.4 to 3.7 m (8 to 12 ft) in each direction. For exterior applications, movement joints should be placed at least every 2.4 to 3.7 m in each direction.

TCNA recommends the movement joint width be a minimum of 9.5 mm (3/8 in.) wide for exterior applications when the field movement joints are 2.4 m on center (oc), but recommends a minimum of 12.7 mm (1/2 in.) wide joints for exterior applications when the field movement joints are 3.7 m oc. TCNA states:

minimum widths of movement joints must be increased 1.6 mm (1/16 in.) for each 9.44 C (15 F) tile surface temperature change greater than 37.8 C (100 F) between summer high and winter low.

The aforementioned ASTM C1472 is valuable because it provides the coefficient of linear thermal movement for different materials, along with the temperature range of various geographic areas and mathematical formulas to determine the required joint widths for the respective conditions.

To ensure a longlasting limestone installation, architects must specify the requirements for movement joint design and placement, along with the correct type of sealant for fi lling those joints.

To ensure a longlasting limestone installation, architects must specify the requirements for movement joint design and placement, along with the correct type of sealant for filling those joints.

To what degree the respective substrate needs movement joints depends on the standards the substrate must meet. For instance, a plaster substrate per ASTM C1063, Standard Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-based Plaster, requires control joints installed in walls to delineate areas not more than 13.4 m2 (144 sf). The distance between control joints shall not exceed 5.5 m (18 ft) in either direction or a length-to-width ratio of 2.5 to 1.

Concrete also has standards that vary depending on its structure, thickness, and design mix.

Detail EJ171 states all underlying movement joints in the substrate need to continue through the tile assembly. Typically, this means that in addition to honoring the substrate movement joints, the tile assembly needs additional movement joints within its assembly.

If there is a mortar bed over the substrate, then the movement joint has to be continuous through it to the tile surface, which is considered an expansion joint. If the tile is being bonded to the substrate, then the movement joints not continuing up from a substrate movement joint are generic movement joints. These are often the same width as the grout joints if it was designed to work at that width. The movement joint widths within the tilework should never be narrower than the substrate joint on which it is placed.

Crack-isolation membranes
Some manufacturers of products meeting American National Standards Institute (ANSI) A118.12, Specification for Crack-isolation Membranes for Thin-set Ceramic Tile and Dimension Stone Installations, allow their membrane to cover non-structural movement joints (i.e. those that move horizontally, but not vertically) such as saw-cut or cold control joints. However, TCNA does not recommend this.

Structural expansion joints can never be covered with membranes as the vertical displacement cannot be mitigated with a crack-isolation membrane. (The membrane manufacturers require movement joints be installed within the tile assembly, and some allow those joints to not line up exactly over the substrate joints.)

The appropriate design of a movement joint is based on the tile or stone assembly’s confi guration and substrate type.

The appropriate design of a movement joint is based on the tile or stone assembly’s configuration and substrate type.

Each manufacturer of crack-isolation membranes may have different recommendations and limitations, so it is always important to follow the accompanying instructions. Some membranes are made of a bitumen material that is incompatible with certain types of sealants used to fill the movement joints.

TCNA’s Detail F125, “Partial- and Full-crack Isolation Membrane,” provide guidelines for isolating non-structural cracks with an ANSI A118.12 product. It is important to note this detail for both ceramic tile and stone applications recommends a movement joint be placed at one or both ends of the tile bridging the underlying crack, as recommended by the membrane manufacturer.

Types of movement joints
The different types of movement joints are shown in the TCNA Handbook in the EJ171 section. Expansion joints are normally considered structural joints that can possibly move vertically. They are found in concrete substrates to isolate one portion of the slab from the other, and in mortar beds as either an extension of the concrete expansion joint or just to isolate one portion of the mortar bed from the other.

A cold joint is the dividing point where two adjacent concrete pours were placed at different times. These weak points are more likely to develop cracks and have to be treated as a movement joint.

Construction or contraction joints are saw-cut concrete control joints that must also be treated as movement joints. The concrete is saw-cut at this predetermined spot, making it a weak point where the concrete will crack (rather than having it crack at a random location). There are also various types of perimeter movement joints, which are found at restraining walls or transition points from one plane to another that are all more likely to be subjected to some type of movement. Tile must be allowed to move to avoid damages.

Sealant considerations
Not only is the design of the movement joints important to a tile installation’s success, but so is the type of sealant or caulking used to fill those joints. TCNA EJ171 states a product meeting ASTM C920, Standard Specification for Elastomeric Joint Sealants, must be used to fill movement joints of all types. Such sealants include high-quality silicone, urethanes, and polysulfide materials. These types of sealants are normally rated as highly weather-resistant with high elongation properties, and high adhesion characteristics that come with 20-year commercial warranties. Too often, one finds installers using some type of acrylic, latex, or siliconized sealant, because they are easier to work with, but these sealants have low performance values and basically no warranty.

Various sealants have different physical properties and performance capabilities. TCNA and the referenced ASTM standards provide guidelines and nomenclature for designating the appropriate type, grade, class, and use for the intended application. For instance, some sealants are not suitable for foot or vehicle traffic, so one must specify “Use T” for those applications.

A traffic sealant should have a Shore A hardness of 35 or greater, which is critical because otherwise the surface could be dangerous to those who wear high heels. (Found on data sheets, Shore A is a physical property of all sealants; it indicates how hard it is in terms of resistance to penetrations or point loads.) High heels will penetrate a softer sealant and can cause a tripping hazard.

There are sealants with fire or acoustical ratings that are required for certain applications; some cannot be used in a submerged application, while others cannot be subjected to certain chemicals. Not all ASTM C920 sealants are compatible with natural stone and could cause the stone to stain. Some sealants require the surfaces to be primed after cleaning the joints and before installation. These are all important concerns to be addressed in the specification to ensure the correct material is used for the intended application.

Various sealants have different physical properties and performance capabilities. Traffi c sealants need a Shore A hardness of at least 35 to ensure those with high heels do not dig into the material, leading to trips and falls.

Various sealants have different physical properties
and performance capabilities. Traffic sealants need a Shore A hardness of at least 35 to ensure those with high heels do not dig into the material, leading
to trips and falls.

highHeelMarkOnSealant3highHeelMarksOnSealant01

It is important movement joints be properly constructed per industry standards. There are also numerous requirements sealant manufacturers specify in order for their products to perform as advertised. Sealants require only ‘two-point contact,’ meaning they are only to adhere to the two opposite sides of the movement joint for optimal performance. They are not to bond to the bottom of the joint, otherwise the sealant will not achieve the published elongation characteristics. A bond-breaking polyethylene tape or foam must be inserted into the joint prior to installing the sealant so the sealant will not bond to it.

To ensure the sealant achieves its published elongation characteristics, care must be taken to ensure it is applied neither too thin nor thick into the joint; the foam backer, installed at the prescribed depth, helps with this. The sealant must be at least 6.4 mm (1/4 in.) thick, and the width to depth ratio should be 2:1 for optimal performance. Generally, sealant companies want a minimum 6.4-mm wide joint, but 3-mm (1/8-in.) is acceptable for non-moving joints (e.g. adhered tile applications).

Additionally, movement joints must be completely filled with the appropriate backing below the sealant, so there are no voids to collect moisture. It is generally best to use closed cell foam, but some sealants require open cell to manage the sealants’ off-gassing while curing. For thin tiles—such as the 6.4-mm thick mosaics—or some of the newer large 3-mm thin porcelain tile panels, it is more problematic to try to install a bond-breaking tape in the movement joint. It is better to leave it out, since it is an adhered non-moving joint that will not require higher performance.

There are prefabricated movement joints made of metal sides and legs with plastic inserts adhered under the tiles on either side of the movement joint. There are also metal L-shapes that can be installed under the tiles on either side of the movement joint and then filled with the appropriate sealant. On one hand, these provide protection to the tile edges and the plastic inserts are conveniently replaceable; on the other hand, they restrain the tile movement since the metal angles are bonded to the substrate. This may not be a big problem if the tile is bonded well and they are installed frequent enough, but this author has seen cases where the tile was not sufficiently bonded, the movement joints were properly spaced, and the tile tented. Since tile assemblies move one way or the other, movement joints should not restrain movement.

Keystone Fashion Mall (Indianapolis, Indiana) has a striking tiled fl oor that benefi ts from having adequate consideration placed into the location and type of movement and expansion joint. Photo © Adam Novak Photography. Photo courtesy Crossville Inc.

Keystone Fashion Mall (Indianapolis, Indiana) has a  striking tiled floor that benefits from having adequate consideration placed into the location and type of movement and expansion joint. Photo © Adam Novak Photography. Photo courtesy Crossville Inc.

Circumventing aesthetic problems
Too often, movement joints are left out of installations with the common excuse being the owner did not want those ‘ugly’ joints marring their tiles. (Of course, their absence can cause even uglier failures.) When specifiers take the time to design the movement joints into the installation, they can accentuate features to make joints virtually unnoticeable.

Manufacturers of one-part silicone sealants have a broad range of colors available and on large jobs they will make custom colors to match the grout. Two-part urethane sealants can be mixed on the job by experienced sealant installers and can easily match the color of the tile grout. By placing the movement joints more frequently, they can be made narrower, matching the width of the grout.

For tile patterns with staggered joints, the designer can use the staggered grout joint (referred to as a saw-tooth joints or zipper joints) as a generic movement joint to make it less noticeable. When done well, movements are not noticeable and can enhance the installation features.

Specifying strategies
Architects should write the sealant specification for the tile and stone applications in Division 07 under “Sealants.” Still, detailed information should be provided in the Division 04 and 09 sections (for stone and tile), particularly if the tile installer is expected to install the sealant.

The following key points, as related to movement joints in tile or stone assemblies, should be included in the specification:

Part 1−General Requirements

  1. Refer to Division 07 for Movement Joint Sealants.
  2. Call out the key industry standards, which are: ANSI A108.01, Requirements for Movement Joints; TCNA Handbook for Ceramic, Glass, and Stone Tile Installation; Marble Institute of America (MIA) Dimension Stone Design Manual for Expansion Joints; ASTM C1242, Standard Guide for Selection, Design, and Installation of Dimension Stone Attachment Systems; ASTM C1193, Standard Guide for the Use of Joint Sealants; and ASTM C1472, Standard Guide for Calculating Movement and Other Effects When Establishing Sealant Joint Width.
  3. Prepare a specific quality assurance (QA) section to verify performance of the ASTM C920 sealant material and to verify it will be suitable for the intended application. Test sealant for performance per ASTM C719, Standard Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants Under Cyclic Movement. Test the peel adhesion of the sealant per ASTM C794, Standard Test Method for Adhesion-in-peel of Elastomeric Joint Sealants. For stone applications, test for staining per ASTM C1248, Standard Test Method for Staining of Porous Substrate by Joint Sealants.
  4. Require a letter from sealant manufacturer stating its product is suitable for the intended use, and outlining its warranty.
  5. For larger projects, specify a sealant installation company that specializes in installing sealants on a full-time basis.
  6. Require a mockup for approval of sealant color and application.

Part 2−Products

  1. Be sure to write performance specifications. Reference specifications only call out products that meet the minimum requirements—in other words, the least-expensive products with the lowest acceptable level of performance.
  2. Call out ASTM C920 sealants. Identify the application and the respective type, grade, class, and use to the intended application. Require a primer if sealant manufacturer requires it with the sealant. Call out the appropriate polyethylene backer foam. Specify the sealant color is to be approved by the architect or owner from the mockup.

Part 3−Execution

  1. Specify the specific movement joint details, for the respective application, from Detail EJ171 in the TCNA Handbook for Ceramic, Glass and Stone Tiles.
  2. Request installers properly clean and prime movement joints as required by the sealant manufacturer. The movement joints need to be completely open and free from any obstructions.
  3. Specify movement joint layout plans, and types of movement joints and sealants, as referenced in TCNA’s Detail EJ171. Tile installers should submit Requests for Interpretation (RFIs) if they are unclear with the requirements.
  4. Specify sealant product installation as per manufacturer’s instructions and industry standards. Similarly, products must be mixed following the manufacturers’ requirements. Further, temperature limitations must never be exceeded. Shading or heat should be required, and the work protected from weather and other trades.
  5. Specify the required sealant surface profile, such as “flush,” “concave,” “recessed,” or “fillet.” Vertical surfaces can be specified to be oriented vertically, horizontally, or at any angle in between so it can control water shedding.
  6. Provide a detailed quality control (QC) plan to be implemented by a third party.
Not only is the design of the movement joints important to a tile or stone fl oor installation’s success, but so is the type of sealant or caulking used to fi ll those joints. Photo courtesy Daltile

Not only is the design of the movement joints important to a tile or stone floor installation’s success, but so is the type of sealant or caulking used to fill those joints. Photo courtesy Daltile

Conclusion
To ensure a long lasting installation, it is critical architects specify and provide the requirements for movement joint design and placement, along with the correct type of sealant or caulking for filling those joints.

In more than three decades, this author has never investigated a tile or stone failure to find all the industry standards and manufacturers’ instructions were followed. Further, the failure is never due to one deficiency, but rather many compounding ones.

The industry standards represent years of experience and scientific testing from a consensus group of industry professionals who volunteer their time and efforts to help architects, installers, and owners have successful tile and stone installations. The key to a successful tile and stone installation is to follow industry standards and to write good specifications. CSI’s MasterFormat and SectionFormat provide the structure for this. When the resulting construction documentation is used correctly and thoroughly, it limits both the designer’s and client’s risk and liability in ceramic tile, glass tile, and stone applications.

Donato Pompo, CTC, CSI, CDT, MBA, is the founder of Ceramic Tile and Stone Consultants (CTaSC), and of the University of Ceramic Tile and Stone (UofCTS). He has more than 35 years of experience in the ceramic tile and stone industry from installation to distribution to manufacturing of installation products. Pompo provides services in forensic investigations, quality control (QC) services for products and installation methods, training programs, testing, and onsite quality control inspection services. He received the 2012 Construction Specifier Magazine Article of the Year Award. Pompo can be reached at donato@ctasc.com.