Section 6 – Tile Installation Preparation and Equipment

6.1 Installation Equipment, Substrate Preparation and Installation Procedures

The construction equipment, substrate preparation process and installation procedures required for each project and region of the world are unique, and therefore it would not be possible to list all the types and combinations of tools, equipment and procedures involved in the installation of wet area and submerged tile applications. This section will present the most common tools, equipment and installation procedures required for each phase of construction. Tool and equipment requirements are determined by the phase of the installation shown below, and further defined by the type of construction, type of finish material, and the type of adhesive installation.

Installation Procedures, Tools and Equipment for Wet Area and Submerged Installations;

Substrate and Finish Material Surface Preparation

Inspection and Evaluation

Access for Preparation and Installation (Rolling Scaffolds for Vertical Work)

Mixing of Adhesives

Installation of Adhesives

Installation of Finish Material

Installation of Joint Grout/Sealants

Substrate and Finish Material Surface Preparation – The first step in substrate preparation is the evaluation of the type of substrate and its surface condition. This includes the levelness (plane or flatness deviation), identification of general defects (e.g. structural cracks, shrinkage cracks, laitance, etc…), the presence of curing compounds or surface hardeners, and contamination. Concrete should have a wood float or light steel trowel finish for proper adhesion of thin-sets or membranes. Over finishing a concrete surface can close the pores and may inhibit proper adhesion of thin-sets and membranes.

The ability of a substrate to be wetted by an adhesive is essential to good adhesion and important in determining the performance of the adhesive in bonding to the substrate. This means that not only should the substrate possess a balance between porosity and texture, but also that the surface must be clean of any contamination such as dust, dirt, oil, paint, curing compounds, sealers, and other bond inhibiting substances that could prevent bonding of an adhesive. The levelness tolerance or smoothness of a substrate surface can also play an important role in allowing proper contact and wetting of an adhesive. Typically, the greater the surface area to which the adhesive is in contact, the better the adhesion.

Adhesive Compatibility – Compatibility plays an important role in determining adhesion between the substrate and the tile or membrane being installed. The substrate material must be compatible not only with adhesive attachment, but also with the type of adhesive under consideration. This means that the substrate material must have good cohesive qualities to resist tensile and sheer stress and not have an adverse reaction with the proposed adhesive or membrane. Similarly, the tile being installed must also be compatible with the adhesive. A general consideration in determining compatibility with adhesives is as follows;

The installation of any finish material with an adhesive will only be as good as the setting materials and the substrate to which the finish material will be bonded. The highest strength adhesives and most careful application with the best quality tile will not overcome a weak or dirty substrate.

This section provides information on the identification of common substrate characteristics and defects, and the preventative and corrective actions necessary for proper surface preparation.

6.2 –Inspection and Evaluation.

6.2 Inspection and Evaluation

Site Visit and Pre-Construction Conference – Prior to commencing ceramic tile work, the tile contractor shall inspect surfaces to receive tile and accessories, and shall notify the architect, general contractor, or other designated authority in writing of any visually obvious defects or conditions that will prevent a satisfactory tile installation. Installation work shall not proceed until satisfactory conditions are provided. Commencing installation of tile work typically means acceptance of substrate and job site conditions.

Job Site Conditions – The following items are examples of potential issues that may need to be addressed prior to commencing the installation:

Contamination – The surface to which tile or stone installation materials will be bonded must be structurally sound, clean and free of all dirt, dust, oil, grease, paint, concrete sealers, curing compounds, and any other material that can act as a bond inhibitor. Dry, dusty concrete and other surfaces should be swept and then dampened with a sponge and water. Any excess water should be allowed to evaporate or be swept off prior to installation of tile setting materials. See Sections 6.4 and 6.7 for more information.

Surface and Ambient Temperatures – During the placement of concrete and installation of other types of substrates, extreme cold or hot temperatures may cause numerous surface or internal defects, including shrinkage cracking, a weak surface layer of hardened concrete caused by premature evaporation, or frost damage. Once the concrete is cured, extreme temperatures of both the ambient air and surface of the substrate can also affect the normal properties of tile adhesives.

Elevated ambient air and surface temperatures (>90°F [32°C]) will accelerate the setting of cement, latex cement and epoxy adhesives. Washing and dampening floors and walls will serve to lower surface temperatures for latex cement mortars and epoxy adhesives. Shading the substrate, if exposed to sunlight, is also effective in lowering surface temperatures, but if ambient temperatures exceed 100°F (35°C), it is advisable to defer work with adhesives and membranes to a more suitable time. Humidity may also have an effect on the curing of membranes and portland cement based adhesives and grouts. Higher humidity will work to slow down cure rates while low humidity will accelerate the curing process.

Weather Conditions and Substrate Protection – The optimum conditions for installation of ceramic tile and stone are temperatures between 60° and 80°F (15° and 25°C), with 50% relative humidity. However, these conditions are atypical, so provisions must be made for variations in climate conditions. Protection applies to the substrate, the installation of adhesives and joint grouts, and also the storage and handling of the finish material.

Hot Temperatures – Protection or corrective action is required if either ambient air or surface temperatures of substrates/finishes go above certain thresholds during installation. Temperature thresholds vary with the types of adhesives and installation accessories, but generally, elevated ambient air (80–100°F [25–35°C]) and surface temperatures will accelerate setting of cement, latex cement, epoxy and silicone adhesives. Washing and dampening floors and walls will not only remove some contaminants, but also serve to lower surface temperatures by evaporative cooling for cement latex mortars and moisture insensitive epoxy adhesives. Shading surfaces that may be in direct sunlight by erecting temporary tents is also effective in lowering surface temperature, but if ambient air and surface temperatures exceed 100°F (35°C), it is advisable to defer work to another time. If work cannot be deferred, it is also possible to cool additives (water, latex, epoxy liquids) in conjunction with the above techniques.

Cold Temperatures – Protection or corrective action is required if either ambient air or surface temperatures of substrates go below certain thresholds during installation. Temperature thresholds are different for various types of adhesives. Protection and corrective actions to elevate air and surface temperatures to optimum range typically involve enclosing or tenting of work areas, augmented by temporary heating. If temporary heating is employed, it is very important to vent units to the exterior of enclosures to prevent exposure to toxic fumes, and also to prevent build-up of carbon dioxide, which can cause carbonation of cementitious materials. This condition typically occurs when ambient temperatures during installation are around 40°F (5°C) and only affects exposed surfaces. The length of exposure is a function of time and temperature. Cement hydration stops at 32°F (0°C) surface temperature, when water necessary for hydration freezes, and the cement hydration process is severely retarded starting at 40°F (5°C).

Concentration of carbon dioxide can be elevated when temporary heating units are not properly vented outside of any protective enclosure during cold temperatures. As a general rule, air abd surface temperatures should be maintained above 50°F (10°C) during installation of cement, epoxy, and silicone-based products. Some cement adhesive product formulations may allow installation in temperatures close to 32°F (0°C) and rising, however, at this critical ambient air temperature threshold, it is likely that surface temperatures are below freezing due to thermal lag, and hydration or other chemical reaction may not occur at the adhesive interface.

As a simple rule of thumb; for every 18°F (10°C) above 70°F (21°C) cement based and epoxy based materials cure twice as fast. For every 18°F (10°C) below 70°F (21°C) cement based and epoxy based materials take twice as long to cure.

Dry and Windy Conditions – These conditions can cause premature evaporation of water necessary for hydration in cementitious materials, and result in loss of strength. Latex additives are formulated to significantly reduce this drying effect by coating cement with a latex film. However, in extreme dry, windy conditions coupled with high temperatures >90°F (30°C), even latex additives do not provide adequate protection. It is recommended to provide temporary protection against rapid evaporation of moisture during hot, dry, windy conditions in the initial 36 hours after installation of cement mortars, screeds, plasters/renders and cement grouts, and to augment by damp curing with periodic daily water misting. Cement based adhesives are only susceptible to premature drying between the spreading of adhesive and the installation of the finish, and requires only temporary protection from dry, high wind speeds during the open or exposed time of the adhesive.

Wet Conditions – Certain materials used in ceramic tile and stone assemblies can be moisture sensitive. For example, the strength of cementitious adhesives can be reduced from constant exposure to wet or damp substrates. Some materials, such as waterproofing membranes, may not cure properly or may delaminate from a continually wet or damp substrate. A damp substrate may also contribute to the formation of efflorescence. This is a particular concern not only from normal rain exposure during construction, but also in areas of an installation, which may be exposed to rising dampness at ground level, or in areas where leaks from poor design or construction cause continual dampness in the substrate. When specifying liquid latex or a dry redispersible polymer adhesive mortar, verify with the manufacturer that the polymer formulation is not water soluble. However, even formulations that are not soluble when dry are vulnerable to rain during the initial set period (typically 12–24 hours). Therefore, it is essential to provide protection from any significant rain or washing within this period to avoid loss of strength and prevent possible fluid or latex migration staining.

6.3 Moisture Content of Concrete

Materials used in tile and stone installation applications can be affected by moisture during the installation and curing phase. For example, the strength of cementitious adhesives can be reduced from constant exposure to wet or damp substrates. Some materials, such as waterproofing membranes, may not cure properly or may delaminate from a continually wet substrate. A damp substrate may also contribute to the formation of efflorescence. Concrete with a high moisture vapor emission rate (MVER) may also have an impact on a tile or stone installation.

There are generally three tests that are used to determine moisture content in concrete. The three tests are:

1. Calcium Chloride (ASTM F1869 – Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloors Using Anhydrous Calcium Chloride).

The Calcium Chloride test involves placing a Petri dish of calcium chloride (covered by a plastic dome adhered to the concrete) on the concrete and allowing the Petri dish to remain in place between 60–72 hours. The calcium chloride absorbs any moisture vapor that transmits through the concrete within the plastic dome. The results of a calcium chloride test measures the amount of moisture absorbed and results are stated in pounds per 1,000 ft2 (92.9 m2) in a 24-hour period. Please note that the ASTM F1869 test should only be conducted in interior conditions when the building is completely enclosed and the air conditioning or heating system is turned on, unless otherwise instructed by the test kit manufacturer.

2. Relative Humidity (ASTM F2170 – Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes).

The Relative Humidity test involves placing probes in the concrete and taking readings with a hygrometer. A relative humidity reading of 75% or below is acceptable for most tile applications. Please note that the ASTM F2170 test should only be conducted in interior conditions when the building is completely enclosed and air conditioning or heating system is turned on, unless otherwise instructed by the probe manufacturer.

3. Plastic Sheet Method (ASTM D4263 – Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method).

The Plastic Sheet Method involves taping an 18" × 18" (450 mm × 450 mm) piece of plastic on the concrete and allowing the plastic to remain in place for 18 - 24 hours to determine if any moisture has accumulated under the plastic when it is removed. Please note that the ASTM D-4263 test should only be conducted in conditions as stated in the ASTM D4263 document.

Both ASTM F1869 and ASTM F2170 are quantitative tests (stating approximately how much moisture is present) while ASTM D4263 is a qualitative test (stating that moisture is present but not how much), and all are a “snapshot” of moisture vapor emission during the testing period.

Figure 6.1 – ASTM F1869 Calcium Chloride Test Kit and ASTM F2170 Relative Humidity Meter (Photos courtesy of George Donnelly Testing & Inspections at www.moisturetesting.com).

Concrete Curing and Age of Concrete – The age of a concrete substrate is important based on the fact that as concrete cures and loses moisture, it shrinks. A common misconception is that concrete completes shrinking in 28 days. This is not true. Thick sections of concrete may take over 2 years to reach the point of ultimate shrinkage. Under normal conditions, 28 days is the time that it typically takes for concrete to reach its full design strength. At that point, concrete will have maximum tensile strength and can better resist the effects of shrinkage and stress concentration.

Depending upon the curing techniques and exposure to humidity or moisture, there may be very little shrinkage in the first 28 days. Flexible adhesives, certain latex or polymer fortified thin-set mortars (e.g. LATICRETE® 254 Platinum or LATICRETE 211 Powder gauged with LATICRETE 4237 Latex Additive), can accommodate the shrinkage movement and stress that may occur in concrete less than 28 days old. In some cases it may be recommended to wait a minimum of 30–45 days to reduce the probability of concentrated stress on the adhesive interface. Some building regulations or codes may require longer waiting periods of up to 6 months. After this period, resistance to concentrated stress is provided by the tensile strength gain of the concrete, and its ability to shrink as a composite assembly. The effect of the remaining shrinkage is significantly reduced by its distribution over time and accommodated by the use of flexible adhesives.

Cracking – Freshly placed concrete undergoes a temperature rise from the heat generated by cement hydration, resulting in an increase in volume. As the concrete cools to the surrounding temperature, it contracts and is susceptible to what is termed “plastic shrinkage” cracking due to the low tensile strength within the first several hours after the pour.

Concrete also undergoes shrinkage as it dries out, and can crack from build-up of tensile stress. Rapid evaporation of moisture results in shrinkage at an early stage where the concrete does not have adequate tensile strength to resist even contraction. Concrete is most susceptible to drying shrinkage cracking within the first 28 days of placement during which it develops adequate tensile strength to resist a more evenly distributed and less rapid rate of shrinkage. It is for this reason that it is recommended to wait 30–45 days before direct application of adhesive mortars.

Plastic shrinkage occurs before concrete reaches its’ initial set, while drying shrinkage occurs after the concrete sets. These types of shrinkage cracks generally do not produce cracks larger than 1/8" (3 mm) in width.

Treating Shrinkage Cracks – There are two different ways to treat shrinkage cracks. The first way is detailed in the LATICRETE Architectural Guidebook – ES-F125 (available at www.laticrete.com/ag) or TCA Handbook for Ceramic Tile Installation – F125. This method only treats the individual crack and not the entire area. This method may suffice for areas that are not completely submerged (such as pool decks or natatorium locker rooms). However, it will not be appropriate for areas that are constantly submerged and require full waterproofing/anti-fracture membrane treatment to create a complete waterproof installation.

The second method of treating the shrinkage crack would be detailed in the LATICRETE Architectural Guidebook – ES-F125A (available at www.laticrete.com/ag) or TCA Handbook for Ceramic Tile Installation – F125A. This method uses the anti-fracture/waterproofing membrane over the entire floor. Following this method will help to protect the finished installation from cracks currently in the concrete substrate and any cracks which may develop over time. This is the preferred method for constant wet area and submerged applications.

Structural Cracks – There is no tile installation practice or method for treating any crack over 1/8" (3 mm) wide or cracks that experience differential vertical movement. These cracks are considered structural in nature and would require determination of the cause of the crack. Once the cause of the structural movement is determined, it must be remedied prior to the installation of the tile system. Repair techniques can vary and a structural engineer should be consulted prior to any remediation or installation of a tile system.

Excessive foundation settlement and movement can be caused by building on expansive clay, compressible or improperly compacted fill soils, or improper maintenance around foundations. Whatever the cause, settlement can destroy the value of a structure and even render it unsafe. In any case, water is the basic culprit in the vast majority of expansive soil problems. Specific components of certain soils tend to swell or shrink with variations in moisture. The extent of this movement varies from soil type to soil type.

When unstable soils are used as a base for a foundation, the tendency for movement is transmitted to the foundation. Since soil movement is rarely uniform, the foundation is subject to a vertical differential movement or upheaval. If all the soil beneath a foundation swells uniformly, there usually is no problem. Problems occur, however, when only part of the slab settles. Then, differential movement causes cracks or other damage. Once again this condition must be corrected before any tile installation can occur.

6.4 Potential Bond Breaking Materials

A tile installation is only as good as its adhesion to the substrate and the tile. An adhesive, in any form, will bond to the first thing it comes in contact with. If that material is dirt, dust, paint, or any other impediment that is lying on a surface, the adhesion to that substrate can be compromised. The importance of a good, clean surface cannot be over emphasized, regardless of the substrate or tile adhesive.

Laitance – Laitance is a surface defect in concrete where a thin layer of weakened portland cement fines have migrated to the surface with excess “bleed” water or air from unconsolidated air pockets. Once the excess water evaporates, it leaves behind a thin layer of what appears to be a hard concrete surface, but in reality is weakened due to the high water to cement ratio at the surface. Laitance has a very low tensile strength, and therefore the adhesion of tile will be limited by the low strength of the laitance.

The removal of laitance by mechanical methods, including the use of chipping hammers or scarifying machines, is recommended. The contaminated concrete surface should be removed until sound, clean concrete is encountered. Measurement of surface tensile strength and the absence of loose material are good indicators of sound concrete.

Abrasive blasting by means of a dry or wet blasting process, or, bead/shot blast methods are also acceptable for the removal of laitance on new and fully cured concrete. Compressed air used in these methods must be oil free. Since wet abrasive blasting reintroduces moisture into the concrete, sufficient drying time must be allowed.

Curing Compounds, Sealers and Form Release Agents – Liquid curing compounds and sealers are topically applied spray-on materials, which are designed to keep moisture in the slab. The constant amount of water kept in the concrete by the curing compounds helps accelerate the curing time and improve the performance of the concrete. Curing compounds and concrete sealers are frequently used in all types of construction, especially in fast track jobs. Unfortunately, all types of curing compounds, concrete sealers and surface hardeners must be completely removed from substrates prior to the installation of tile or any installation accessories, including waterproofing membranes. The preferred methods to remove these curing compounds from the surface would be to bead-blast or shot-blast the horizontal concrete surface, and to high pressure wash vertical concrete surfaces.

There is a very simple and effective test to identify the presence of curing compounds, sealers or other bond breaking conditions. Simply sprinkle a few drops of water onto the substrate and see what happens. If water absorbs into the slab then it is usually suitable for the direct adhesion of tile. On the other hand, if the water beads up on the concrete surface (like water on a freshly waxed car) then there is something present on the concrete surface that can inhibit proper adhesion of the tile adhesive. While the water test is commonly used to determine the presence of bond inhibiting msubstances, it may not always be accurate.

In addition, to determine if bond inhibiting contamination such as oil or curing compounds are present on concrete, conduct the following test: taking proper safety precautions, mix a 1:1 solution of aqueous hydrochloric (muriatic) acid and water, and place a few drops in various locations. If the solution causes foaming action, then the acid is allowed to react freely with the alkaline concrete, indicating that there is no likely contamination. If there is little or no reaction, chances are the surface is contaminated with oil or curing compounds. Acids do not affect or remove oily or waxy residue, therefore, mechanical removal may be necessary.

Any surface to receive tile will always be exposed to varying degrees of contamination, especially normal construction dust and debris. Tile is often the last phase of the construction of a building. Imagine all other trades have been in and finished their certain part of the construction, (i.e. sheet rock, plumbing, painting, and many other trades). There is often paint, drywall compound, oil and other materials on the concrete from prior trades that need to be removed. One of the most difficult tasks for any installer is the preparation of the surface before the installation of the tile commences. However, it is one of the most important steps, if not the most important step, to providing for a successful, long lasting tile installation. Cleaning the surface is mandatory before tile is placed, and sometimes multiple washings will have to take place before tiling. Just sweeping the floor is not good enough!

6.5 Substrate Preparation Equipment and Procedures

Contamination Removal – If contamination removal is required, or if surface damage or defects exist, bulk surface removal may be necessary to prepare the substrate. There are several methods of removal, but it is important to select a method that is appropriate to the substrate material and will not cause damage to the sound material below the surface.

Methods of Removal – There are several methods for removing contamination from a substrate to better prepare for the application of tile and stone installation materials. These include;

Mechanical Chipping, Scarifying and Grinding – Mechanical chipping, scarifying or grinding methods are recommended only when substrate defects and/or contamination exist in isolated areas and require bulk surface removal greater than 1/4" (6 mm) in depth. Chipping with a pneumatic square tip chisel or grinding with an angle grinder is a common mechanical removal technique.

Figure 6.2 – Saw Tec® Dustless Grinding. This method is ideal for spot preparation and solves localized problems.

Shot-blasting and bead blasting – This is a surface preparation method, which uses proprietary equipment to pummel the surface of concrete with steel pellets or ceramic beads at high velocity. The pellets of varying size, are circulated in a closed, self-contained chamber, where the pellets and debris are separated. The debris is collected in one container and the pellets are re-circulated for continued use. This is the preferred method of substrate preparation when removal of a thin layer of the concrete surface is required, especially the removal of surface films (e.g. curing compounds or sealers) or paint.

Figure 6.3 – Shot-blasting is ideal for areas outside of pool tanks and water features and for areas where access by the equipment is not an issue.

Water-Blasting – High pressure water blasting using pressures over 3,000-10,000 psi (21–69 MPa) will remove the top surface layer of concrete and expose aggregate to provide a clean, rough surface. Thorough rinsing of the surface with water after water blasting is necessary to remove any laitance. Water-blasting is only recommended on fully cured concrete because of the high pressure. Proper allowance must be made to allow for the excess water in the slab to dry. This method is commonly used on vertical surfaces and is ideal for preparation of pool tanks, water features and vertical surfaces.

Figure 6.4 – High pressure water wash (water-blasting) will remove the required amount of contaminated concrete. Photo courtesy of Turtleskin, Inc. (protective clothing and gear for use with water blasting) Blastrac® Inc. Shot Blasting Machinery. This method is ideal for preparation of pool tanks, water features and vertical surfaces.

Acid Etching – Acid etching or cleaning is never recommended to clean a surface prior to receiving tile. If an acid is not neutralized or cleaned properly after the cleaning takes place, it can continue to weaken the portland cement in the concrete and tile installation materials when in the presence of moisture. Acid must be neutralized with Tri-Sodium Phosphate (TSP) or baking soda mixed with water and then completely rinsed to ensure all the acid is removed from the surface. Again, acid is not recommended for cleaning concrete, since it has an adverse affect on portland cement. A chemical reaction occurs when portland cement and acid are introduced to each other that can destroy the cement matrix. The interaction between the acid and the portland cement exposes the concrete aggregates and weakens the concrete.

Acid can also leave a white powdery substance on the surface which can act as a bond breaker for any tile installation material. To avoid any potential problems it is best to avoid the use of acids as a substrate preparation method.

6.6 Substrate Tolerances

Flatness and Levelness – A flat, plane substrate is an important concern for any tile installation requiring a direct bond adhesive application. According to industry requirements (ANSI A108.01 – 3.2) the following are the requirements for flatness of concrete slabs;

ANSI A108.01 3.2.1.1 – Where the mortar bed for the tile floors to be bonded to the concrete slabs; “Screed finish concrete slabs that are to receive ceramic tile. Maximum permissible variation in the plane or slope is 1/4" in 10' (6 mm in 3 m) from the required plane when measured with a straight-edge… Properly cure slabs without using liquid curing compounds or other coatings.”

ANSI A108.01 3.2.1.2 – Where tile is to be bonded directly to concrete with one of the thin-set methods; “Steel trowel and fine-broom finish concrete slabs that are to receive ceramic tile. Maximum permissible variation of 1/4" in 10' (6 mm in 3 m) from the required plane. Cure concrete slabs that are to receive tile before tile application. Do not use liquid curing compounds or other coatings that may prevent bonding of the tile setting materials to slabs. Slab shall be dry at time of tile installation. Since any cracking of the concrete slab will be transmitted to the finished surface, take all precautions to prevent cracks in the concrete. Use control joints through the slab and tile finish as specified or where cracks are anticipated.”

Large format tile and stone applications may require a tighter tolerance of 1/8" in 10' (3 mm in 3 m) from the required plane. Greater deviations prevent the proper installation of tile into the adhesive, which may result in numerous problems, including loss of bond or excessive lippage.

If levelness tolerance is exceeded, then it may be necessary to employ remedial work, such as re-construction, patching, grinding, or installation of leveling mortars, screeds, or renders (e.g. LATICRETE 3701 Fortified Mortar Bed; or, LATICRETE® 3701 Fortified Mortar Bed or LATICRETE 226 Thick Bed Mortar mixed with LATICRETE 3701 Mortar Admix).

If the tolerance is within specifications, then the use of a medium bed mortar and a larger size notch trowel can alleviate any minor defects in the substrate. Please note that while a medium mortar may be used to correct minor substrate defects, it is important to stay within the product manufacturers guidelines for thickness of the setting material.

With most adhesives or cement leveling mortars/renders, such as latex cement mortars or moisture insensitive adhesives, the substrate can be damp during installation; however, it cannot be saturated. The objective is not to saturate the floor, but to make sure all the dust and debris is removed before tiling.

6.7 Final Surface (Residue) Cleaning

Once all corrections to the substrate have been made, the final and most important step of substrate preparation is the final cleaning, not only of the residue from contamination and bulk removal processes described above, but also cleaning of loose particles and dust from airborne contamination.

The final cleaning is considered minimum preparation for all substrates. Final cleaning can be accomplished by pressurized water as mentioned above, but can also be accomplished with standard pressure water and some agitation to eliminate the bond breaking effect of dust films. In some cases, airborne contamination is constant, requiring frequent washing just prior to installation of cement leveling plaster/renders, adhesive mortars, or membranes.

There is no exception from this general rule; and the only variation is the drying time of the substrate prior to the application of the adhesive. Drying time is dependent on the type of adhesive being used. With most adhesives, the substrate can be damp, with no standing water. A surface film of water will inhibit grab and bond of even water insensitive cement and epoxy based adhesives. The use of a damp sponge just prior to installation of tile is an industry accepted method to ensure that the substrate is cleaned of any dirt and construction dust on the properly prepared substrate.

Monitor the pH level of the substrate prior to laying tile. Do not install tile until the pH has a value less than 10. Properly balance the pool water immediately upon filling.

6.8 Finish Material Preparation

Cleaning of the tile back and substrate surface prevent contamination from inhibiting adhesive bond. While careful consideration is often given to the preparation of the substrate, preparation and cleaning of the finish material bonding surface is an often overlooked specification item or quality control checkpoint. Considerations are dependent on the type of finish material.

Types of Finish Materials

Ceramic or Porcelain Tile – The bonding surface of the tiles may be contaminated with dirt or dust from normal manufacturing, storage and handling. Porcelain tile may have a coating of a release agent (known by terms such as bauxite, engobe) which prevents fusion of the tile to kiln surfaces during the firing process. The type, amount, and degree of removal of release agent prior to shipping will vary according to manufacturer or production batch. It is recommended to wipe each tile with a clean, damp towel or sponge during or just prior to installation to maximize adhesive bond. Redispersible polymer cement and latex cement adhesive mortars can be applied to a damp, but not dripping wet surfaces.

Stone – Fabrication dust from cutting, polishing and detailing may leave a dusty residue on the bonding side of the stones. The back of the stone should also be wiped down with a clean damp sponge or cloth and allowed to dry prior to installation for maximum adhesive bond.

Glass Tile – The preparation of a glass tile prior to installation will vary by glass tile manufacturer. Therefore, it is important to follow the glass tile manufacturer’s written installation instructions. In many cases, the glass tiles should be wiped and cleaned of any dust or residue with clean water and then should be wiped dry with a clean cloth prior to installation.

6.9 Adhesive Mixing Equipment and Procedures

Equipment and tools required for mixing of adhesives are primarily dependent on the type of adhesive and construction site conditions such as the size of project.

Types of Adhesives

Latex Cement Based Adhesive Mortars

Manual Mixing

Bucket, Trowel and Mixing Paddle

Mechanical Mixing

Low Speed Drill (<300 rpm) and Non-Air Entraining Mixer Blade (Figure 6.6)

Rotating Blade (Forced Action) Batch Mortar Mixer (Figure 6.7)

Note: Rotating drum type concrete mixers are not suitable for mixing adhesive mortars. In mixing cement adhesive mortars, always add the gauging liquid (water or latex additive) to the mixing container or batch mixer first. Begin mixing and add the dry cement based powder gradually until all powder is wet, then continue mixing continuously for approximately one minute or until mortar is wet and plastic. If using site prepared powder mixes of portland cement and sand, add the sand first until it is wet, and then add the cement powder. Take caution to prevent over-mixing by blending only until the mortar is wet and plastic in accordance with the manufacturer’s instructions. Over-mixing can entrap air in the wet mortar and result in reduced density (high absorption will reduce freeze thaw stability) and strength.

Epoxy Adhesive

Manual Mixing

Bucket and Trowel

Mechanical Mixing

Low Speed Drill (<300 rpm) and Non-Air Entraining Mixer Blade

The mixing instructions for epoxy adhesives vary according to the manufacturer’s formulations. The most common epoxy adhesives are three component products, which involve mixing two liquid components (resin and hardener), and a powder component (silica filler). The liquids are mixed together first and fully blended before adding filler powder. There are several important considerations in mixing epoxies. First, the chemical reaction begins immediately upon mixing the epoxy resin and hardener. Because the “pot” or useful life of the adhesive is relatively short (1 hour) and can be further reduced by ambient temperatures above 70°F (21°C), all preparation for mixing and installation of the epoxy adhesive should be made in advance. Mixing should also be made in quantities that can be installed within the prescribed useful life under installation conditions. Most epoxy adhesives cure by an exothermic or heat generating chemical reaction beginning with the mixing of the liquid components. The useful life of the epoxy not only begins before adding the filler powder, but the heat generated may accelerate the curing process in many formulations. Removal of the mixed epoxy from the mixing container is one technique used to dissipate heat generation and minimize set acceleration. Liquid components may also be cooled if anticipated ambient or surface temperatures will significantly exceed recommended use temperature range. Conversely, epoxy adhesive cure is retarded by cold temperatures, and the curing process will slow significantly at temperatures below 40°F (5°C); the curing process will continue unaffected if temperatures are raised.

Figure 6.5 – Variety of Mixing Paddles used for Drill Type Mixers.

Mortar Beds

Aluminum Straight Edges and Screeds

Concrete/Mortar Bed finishing trowel

Wheelbarrows

Square Edges Shovels

Steel Rakes

Walking Boards

Mortar Bed / Tile Shoes

Mortar Mixer

Figure 6.6 – Rotating Blade Type Mixer.

6.10 Installation Equipment and Procedures

The following are the basic tools and equipment used for the installation of ceramic tile, porcelain tile, glass tile and stone finishes:

Equipment for Application and Bedding of Adhesives and Grout Joints

Notched Steel Trowel

Flat Steel Trowel

Margin Trowel

Hawk

Metal Applicator Gun (Silicone Sealant)

Rubber Mallet

Wood Beating Block

Spacer Shims and Wedges

Grout Float (Cement or Epoxy)

Cutting/Fitting of Finished Materials

Wet Saw (See Figure 6.8)

Ceramic Tile Cutter and Accessories

Figure 6.7 – A commercial grade wet saw is ideal for cutting all types of tile and stone in swimming pool, fountain or water feature applications.

Measurement

Carpenter’s Level

Laser Level

Straight Edge (4'/1200 mm)

Clean-Up

Sponges, Towels

Water Bucket

Solvents (Epoxy or Silicones)

Safety Equipment

Safety Glasses

Rubber Gloves

Dust Mask/Respirator

Safety Belts and Harness

Functions of a Notched Trowel

Gauges the Proper Thickness of Adhesive

Provides Proper Configuration of Adhesive

Aids in Efficient Application of Adhesive

Notched steel trowel – This is the primary and most fundamentally critical installation tool for the thin bed method of installation. The proper thickness of the adhesive layer is dependent on the type and size of finish, the cladding and substrate bonding surface texture, configuration and tolerance from consistent thickness. A “gauged” or “calibrated finish" is one with a consistent thickness and a specified tolerance for deviation; an “ungauged” cladding is not consistent in thickness. Even gauged large format tile and stone can experience thickness tolerances of up to 1/8" (3 mm). Notched steel trowels are available in several sizes and configurations to control thickness of applied adhesive mortar. The configuration of adhesive application is critical to performance of the tile or stone installation. In addition to controlling final thickness of adhesive, the notched configuration results in “ribbons” or “ribs” of adhesive separated by spaces that control bedding or setting of the finish into the adhesive. The spaces allow the ribs of adhesive to fold into one another to decrease the resistance to pressure required for proper contact, and provide a controlled method of filling all air voids and allowing escape of air parallel to the ribs. This function is critical in assuring full contact and coverage of adhesive, not only to ensure maximum bond strength, but also to eliminate air voids or channels, which can harbor or transport water.

Notch Chart

Figure 6.8 – Notched trowel sizes for installation of adhesive mortars.

It is important to maintain the specified notch depth and configuration of notched steel trowels throughout the project. The angle of application can have a significant effect on the height of adhesive ribs, which in turn can affect the height to width ratio necessary for control of thickness and elimination of air voids. Therefore, it is recommended to prohibit the common use of severely worn trowels and to require frequent cleaning and specification of application angle as part of the specification and quality control inspection program. A flat steel trowel is a tool used in applying an initial thin layer of adhesive in positive contact with both the bonding surface of the tile, also known as back-buttering, and the surface of the substrate. The opposite side of a notched trowel typically has a flat edge for this purpose. A rubber mallet (or wood beating block, or hard rubber grout float for smaller tiles) can be used to beat-in the tiles after they are placed to assure full contact with the adhesive, and eliminate any voids in the adhesive layer (Figure 6.10).

Thin Bed Installation Procedure

The following is an abbreviated step-by-step process for the application of thin bed adhesive mortars. Follow the explicit manufacturer’s installation instructions for detailed information. For full installation specifications for thin bed, thick bed and membrane instructions – see section 7.

1. Apply a thin skim coat (1/16"/1.5 mm thick) of thin-set or epoxy adhesive to the properly prepared dampened substrate with the flat side of the trowel; ensure good contact by scratching the edge of the trowel against the surface.

2. Additional thin-set or epoxy adhesive is then applied with the notched side of the trowel. Comb the mortar on the surface with the notched trowel holding it as close as possible to a 90° angle to the substrate. This will ensure the proper size of notches.

Figure 6.9 – A notched trowel has several important functions that contribute to a successful installation of ceramic tile and paver tiles.

3. The ribs of thin-set or epoxy adhesive should be troweled in one direction only, and not in a swirl pattern. If additional thickness of adhesive is needed, add to the back of the tile or stone using the same procedure as on the substrate, making sure that the direction of the combed mortar is identical to the one on the substrate, otherwise, you will end up with notches in two directions that disturb each other and consequently will not allow full contact between the mortar and the back of the tile.

4. As a rule, tile sizes larger than 12" × 12" (300 × 300 mm) should be back buttered. Back buttering not only improves the contact between the mortar and the back of the tile, but also helps to ensure complete coverage. Another important consideration for back buttering is that if the tile is not fully bedded by proper beat-in, the ribs of thin-set or epoxy adhesive, which are not flattened, are being sealed by the coat applied to the back of the tile.

5. The tile should be pressed into place, and either twisted and pressed into position, or for tile sizes 12" × 12" (300 × 300 mm) and greater, slide into position with a back and forth motion perpendicular to the direction of the thin-set or epoxy adhesive ribs.

6. The final step is to beat-in with a rubber mallet to ensure thin-set or epoxy adhesive contact and make surface level with adjacent tiles.

6.11 Grout and Sealant Materials, Methods and Equipment.

Purpose of Grout or Sealant Joints – The joints or spaces between pieces of tile serves several important purposes. Aesthetically, joints serve as a design element, primarily to lend a pleasing scale with any size tile module. Functionally, joints prevent water infiltration, and compensate for varying dimensional tolerances of the tile or stone. More importantly, though, joints lock the tiles into place and provide protection against various delaminating forces. Depending on the joint material, a joint may also act to dissipate shear stress caused by movement.

Compensate for Tile Thickness Tolerances – The joints between tiles compensate for allowable manufacturing or fabrication tolerances, so that consistent dimensions (from center to center of joints or full panel dimensions) can be maintained. As a result, joints must be wide enough to allow variations in the joint width to accommodate manufacturing or fabrication tolerances in the tile without being evident.

Prevent Water Infiltration – Filled joints between tiles allow most surface water to be shed. This helps prevent infiltration of water, which can lead to saturation of the setting bed and substrate, freezing, strength loss and efflorescence. Depending on the grout or sealant material used, and the quality of installation, no grout or tile will be 100% effective against water penetration, so there may always be a small amount of water infiltration by capillary absorption. Therefore, the use of a waterproofing membrane is strongly recommended in wet area applications.

Dissipate Movement Stress -– Probably the most important function of grout or sealant joints is to provide stress resistance and stress relief. The composite locking action with the adhesive layer allows the tile finish to better resist shear and tensile stress. Joints serve to provide stress relief of thermal and moisture movement that could cause delamination or bond failure if the edges of the tiles were butted tightly. Further isolation of movement is handled by separating sections of tile with movement joints (see Section 7.6 – Sealant and section 10 – Movement Joint Specifications and Details). This ensures that the grout or sealant joint will always fail first by relieving unusual compressive stress from expansion before it can overstress the tile finish or adhesive interface. The dissipation of stress provides an additional safety factor against dangerous delamination or bond failure.

Grout Installation Procedure – The following is an abbreviated step by step process for the installation of grout. Follow the explicit manufacturer installation instructions for detailed information. For full grout installation specifications – see section 10.

1. Prior to grouting, it is essential to conduct a test panel (preferably as part of the pre-construction quality assurance procedures) to test the grouting installation and clean-up procedures under actual climatic conditions. During this test, you may determine the need to apply a grout release or sealer to the tile prior to grouting in order to aid in clean-up and prevent pigment stain and absorption of cement paste (especially latex cement or epoxy liquids) into the pores of the tile. This test may also determine if additional adjustments are necessary, such as saturation of the finish with water to reduce temperature, lower absorption, and aid in installation and cleaning. Conducting a test panel will also allow for final determination of the grout color in relation to the tile, lighting and other environmental factors to which the finished installation will be exposed.

2. Wait a minimum of 24 hours after installation of tile before grouting.

3. Before commencing with grouting, remove all temporary spacers or wedges; rake any loose excess adhesive mortar from joints. Remove any hardened thin-set or epoxy adhesive which is above half the depth of the tile. Insert temporary filler (rope, foam rod) in movement joints to protect from filling with hard grout material. Wipe the tile surface with a sponge or towel dampened with water to remove dirt and to aid in cleanup.

4. Apply the grout joint material with a rubber grout float, making sure to pack joints full.

Figure 6.10 – Grout joint installation equipment – floats.

5. Remove excess grout by squeegee action with the edge of the rubber grout float diagonal to the joints to prevent pulling of grout from the joints.

6. Allow grout to take an initial set and follow the appropriate cleanup process for the specific grout type used as stated in the manufacturer’s written installation instructions.

7. Any remaining weakened grout haze or film should be removed within 24 hours using a damp sponge or towel.

Silicone or Urethane Sealant Joint Fillers

Installation procedures for sealant joint fillers are the same as for movement joints

(see Section 7 – Sealant and Section 10 – Expansion Joint Specification and Details).

6.12 Post Installation Cleaning

Most clean-up should occur during the progress of the installation. Hardened adhesive and grout joint residue may require more aggressive mechanical or chemical removal methods than required while still relatively fresh. Water based cement and latex cement adhesives clean easily with water while fresh, or may require minor scrubbing or careful scraping together with water within the first day. Epoxy and silicone adhesives and joint sealants may require more aggressive scrubbing and solvents if residue is greater than 24 hours old.

6.13 Mechanical Means and Methods

As an alternative to the common traditional means and methods of installation, swimming pool and natatorium applications lend themselves to the use of mechanized means and methods due to the size and uniqueness of the application. In many cases, mechanized equipment can greatly improve productivity and lower labor and installation costs. Generally, the set up and clean up time of the equipment factors into the decision of whether to use the mechanized equipment. The following sections provide an alternative to the traditional means that are typically used in most ceramic tile installations.

Power Screeds – Power screeds are used as an alternative to the conventional wood or aluminum straight-edge methods of leveling and “pulling” of mortar beds. The power screeds run on small electric powered or gas powered engines. The vibration that is caused helps to facilitate the screeding. The power screed sits on aluminum ribbons that set to the desired height. The power screed is pulled over the ribbons to compact and level the mortar faster and more efficiently than manual methods.

Power Grouting – Power grouting is accomplished by using a mechanized grout spreading machine. The grout is spread by using rubber blades mounted on a powered, rotating floor machine. This equipment will spread both latex portland cement based and epoxy grouts in an effective manner. These machines pack the joints and strike the excess grout from the face of the tiles. The rubber blades can be changed when excessive wear is noticed. The mechanized power-grouting machine has interchangeable pads to easily convert to the cleanup process. Traditional methods and equipment will still need to be used in small areas where the use of the mechanized equipment becomes impractical.

Figure 6.11 – Raimondi USA – Power Grouting Machine and Accessories.

Figure 6.12 – Raimondi USA – Power Grouting Machine.

Figure 6.13 – Raimondi USA – Low Speed Power Mixing Tub.

Mortar Mixers and Pumps – Mortar mixers and pumps are used as an alternative to conventional mortar mixers. The pump and mixer apparatus effectively mixes and pumps the mortar through a 3" (75 mm) hose to the desired location. The strength and style of these machines varies greatly depending on the amount of mortar to be mixed, the distance to place the mortar, and the amount of mortar to be placed.

Figure 6.14 – Putzmeister USA Pumps.

Figure 6.15 – Mortar is mixed and pumped to area in a combination mortar mixer/pump combination.

Spraying Waterproofing Membranes – Liquid applied waterproofing membranes are typically applied with heavy nap paint rollers. However, on large natatorium and water feature projects, certain liquid applied waterproofing membranes (e.g. LATICRETE® Hydro Ban) can be effectively sprayed to increase productivity. In addition to the conventional means of applying LATICRETE Hydro Ban, (see Data Sheet 663.0 and How To Install Data Sheet 663.5) the airless spraying technique can be used as an alternate means of application. The following are the guidelines for this procedure. Most airless spray units can be used to apply the LATICRETE Hydro Ban.

This procedure will refer to the use of Graco’s Mark IV Electric Airless Sprayer® and the 5900 HD Gas Powered Airless Sprayer. These sprayers are designed for spraying the contents from a 5 gallon (19 pail. Many airless sprayers are similar in design and will accomplish the same purpose.

Figure 6.16 – Graco Company airless spray equipment. A good understanding of the equipment, set up, delivery and cleanup procedures are required in order to effectively spray LATICRETE® Hydro Ban.

Airless Spray Tip Characteristics – It is important to remember that the spray tip orifice size, in conjunction with the fan width size, determines the spray characteristics of the tip.

Examples: As the spray tip orifice size increases, while maintaining the same fan width size, the greater the volume of coating will be applied to the same area. Conversely, the larger the fan width size, while maintaining the same orifice size, will result in the same amount of material being applied over a greater surface area.

Figure 6.17 – Graco Company Typical LTX Sprayer Nozzle.

Tip Size: LTX521 – has an orifice of 0.021"(0.5mm) and a fan width of 10" (250 mm) holding the nozzle 12" (300 mm) away from the substrate.

Tip Size: LTX631 – has an orifice of 0.031" (0.8 mm) and a fan width of 12" (300 mm) holding the nozzle 12" (300 mm) from the substrate.

The use of a spray tip with a smaller orifice will result in less product being delivered to the substrate requiring multiple passes to ensure a complete coating with optimum thickness.

Understanding Tip Wear – Choosing the right spray tip is essential for ensuring a quality finish. When beginning a project, choosing the right tip size and fan width will determine how effective the spraying process will be. The correct tip size will have a direct bearing on how much material is dispensed. However, spray tips will wear with normal use. When a tip wears, the orifice size increases and the fan width decreases so delivery time and product consumption will increase. This causes more liquid to hit a smaller area, which wastes waterproofing membrane and slows productivity. It is important to replace a tip when it gets worn to ensure a precise spray pattern, maximum productivity and a quality finish. Therefore, changing the spray tip often will result in greater productivity.

Tip life varies by coating, so if a tip is worn, replace it. Extend tip life by spraying at the lowest pressure that breaks up the coating into a complete spray pattern (atomize). Do not increase the pump pressure; it only wastes waterproofing membrane and causes unnecessary pump component wear.

Figure 6.18 – The example demonstrates the spray pattern of new and worn spray tips. As wear occurs, the pattern size decreases and the orifice size increases. As a rule of thumb, it is best to replace the spray tips after spraying 30–45 gallons (114–171 liters) of LATICRETE Hydro Ban.

Spray Guns – Follow the specific airless sprayer and spray gun manufacturer’s written instructions when using their specific equipment. Graco Silver Gun Plus® is depicted in the following photo. This spray gun can be used for both vertical and horizontal applications. Some Spray Guns will allow filtering in the gun handle. The filters will need to be periodically cleaned and changed to ensure proper liquid flow through the spray gun and tip.

Figure 6.19 – Graco Company Silver Gun Plus.

Application of LATICRETE® Hydro Ban Follow all surface preparation requirements outlined in Data Sheets 663.0 and 663.5. The sprayer should produce a maximum of 3300 psi (22.8 MPa) with a flow rate of 0.95 to 1.6 GPM (3.6 to 6.0 LPM) using a 0.521 or a 0.631 reversible tip. Keep the unit filled with LATICRETE Hydro Ban to ensure continuous application of liquid. The hose length should not exceed 100' (3000 cm) in length and 3/8" (9 mm) in diameter.

Apply a continuous LATICRETE® Hydro Ban film with an overlapping spray. The wet film has a sage green appearance and dries to a darker olive green color. When the first coat has dried to a uniform olive green color, approximately 45 – 90 minutes at 70°F (21°C), visually inspect the coating for any voids or pinholes. Fill any defects with additional material and apply the second coat at right angles to the first. The wet film thickness should be checked periodically using a wet film gauge to ensure that the appropriate thickness and coverage is achieved. Each wet coat should be 0.015" – 0.022" (0.4 – 0.6 mm) thick. The combined dried coating should be 0.020" – 0.030" (0.5 – 0.8 mm) thick or 0.029" – 0.043" (0.7 – 0.11 mm) wet. Bounce back and overspray will consume more of the LATICRETE Hydro Ban. To achieve the required film thickness, the coating must be free of pinholes and air bubbles. Do not back roll coating. Allow the LATICRETE Hydro Ban to cure in accord with the instructions in Data Sheets 663.0 and 663.5 prior to the installation of the tile or stone finish.

It is important to note that areas not scheduled to receive the LATICRETE Hydro Ban should be taped off and protected from any potential overspray. Expansion and movement joints should be honored and treated as outlined in product Data Sheets 663.0 and 663.5.

NOTES: The operator of the spray equipment must have a working knowledge of the equipment used and be able to adapt to the project conditions as the spraying takes place. As the spray tip wears, adjustments will need to be made. Spray tip selection, pressure adjustments and hose length will have a direct bearing on the results achieved.

Spray Equipment Setup, Clean Up and Maintenance – Follow the airless sprayer manufacturer’s instructions on set up, operation, clean up and maintenance of their equipment. The airless spraying unit should be flushed, clean and free of any contaminants prior to use with LATICRETE Hydro Ban.

Health and Safety – Follow all applicable health and safety requirement when applying LATICRETE® Hydro Ban. The use of protective clothing, safety glasses and a dual cartridge respirator are recommended. See MSDS Sheet on LATICRETE Hydro Ban for complete information.

Airless spray equipment can be purchased by contacting:
Bob Zaffino
The Paint Project, Inc.
Industrial Spray Equipment & Systems
71 West St.
Medfield, MA 02052
Tel. +1.508.359.8003
Fax +1.508.359.8463
e-mail bob@paintproject.com

or

Graco Inc.
Sales/Distribution/Service
P.O. Box 1141
Minneapolis, MN 5540-1441
Tel. 1.800.690.2894
Fax 1.800.334.6955
www.graco.com

1. TCA Handbook for Ceramic Tile Installation, Tile Council of North America, Inc., Anderson, SC.

2. Materials and Methods Standards Association, Bulletins, #3,5,6,9,11,12, 13,16, 1988 edition.

3. American National Standard for the Installation of Ceramic Tile, ANSI A108 series, A 118 series, American National Standards Institute, NY, 2005.

4. Raimondi Tools USA – Mechanized Tools.

5. Putzmeister USA – Mortar Pumps.