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Tile Flooring Technical Information

Caring for Ceramic Tile

Cleaning
All ceramic tiles are stain resistant and require very little maintenance. A basic maintenance program would be to dust mop and spot-mop as necessary, then mop with a cloth-mop and neutral cleaner on a regular basis. However, some tiles will have better dirt hiding capabilities than others, and some will be easier to maintain than others.

Dirt hiding capabilities
Tiles with texture and multiple colors will hide dust and dirt better than tiles with smooth, monochromatic colors.

Slip resistance
A ceramic tile surface is more slip resistant than almost any other flooring surface. However, be aware that an abrasive surface will require an occasional deep cleaning.

Sealing
Glazed ceramic tile floor will never need sealing, waxes or coatings of any kind. Some through body porcelain tiles may; check with the porcelain manufacturer to verify requirements.

Sweeping
Tracked in dirt is abrasive and can damage your floor tile. Sweep floor regularly to prevent loose dust & abrasive particles from scratching your floor. Sweep floor with a dust mop or vacuum sweeper (without a beater brush or bar).

Mopping
Mop floor weekly to maintain appearance using a string or cloth-type mop. Sponge mops can streak your floor and shouldn’t be used. Clear water or neutral pH cleaners are recommended for ceramic tile and grout surfaces. Follow manufacturer instructions on cleaning and rinsing for best results. Protect your investment

– Equip furniture legs with felt floor protectors. Dirt and sand imbedded into plastic or wooden legs act as sandpaper as furniture is moved across your floor.
– Place rugs or mats both inside and outside of exterior entryways.
– Place rugs or mats at areas around kitchen sinks and dishwashers to prevent impact damage from dishes and utensils.
– Damaged ceramic tile floor can usually be replaced and restored to original condition if you have extra tile available from your specific shade.
– Purchase several extra pieces to keep on hand for repairs.
– Contact a licensed tile contractor to make the repair.

Never, Never, Never
– Never seal or wax your ceramic tile. These coatings are unnecessary. They will attract and hold dirt on your floor surface.
– Never use vinegar or bleach for regular cleaning. They can adversely affect the tile and grout with continual use. – Never use steel wool or abrasive cleaners for ongoing maintenance. They can mar your tile surface if used repeatedly.

Keep this in mind
Your ceramic tile can be maintained with minimal effort. Follow these basic care and maintenance guidelines and your floor will retain its beauty for years to come.

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Caring for Stone

Natural stone is an investment that will give you many years of beautiful service. Stone is a natural product and simple care and maintenance will keep it looking beautiful. These are recommendations from the Marble Institute of America

Precautions
Use coasters under all glasses, particularly those containing alcohol or citrus juices. Many common foods and drinks contain acids that will etch or dull the stone surface. Use trivets or placemats under china, ceramics, silver or other objects that can scratch the surface.

All stone surfaces
Clean stone surfaces with neutral cleaner, stone soap (available at hardware stores or from your stone dealer) or a mild liquid dishwashing detergent and warm water. Use a clean rag mop on floors and a soft cloth for other surfaces for best results. Too much cleaner or soap may leave a film and cause streaks. Do not use products that contain lemon, vinegar or other acids on marble or limestone. Rinse the surface thoroughly after washing with the soap solution and dry with a soft cloth. Change the rinse water frequently. Do not use scouring powders or creams; these products contain abrasives that may scratch the surface.

Floor surfaces
Dust mop interior floors frequently using a clean, non-treated dry dust mop. Sand, dirt and grit do the most damage to natural stone surfaces due to their abrasiveness. Mats or area rugs inside and outside an entrance will help to minimize the sand, dirt and grit that will scratch the stone floor. Be sure that the underside of the mat or rug is a non-slip surface. Normally, it will take a person about eight steps on a floor surface to remove sand or dirt from the bottom of their shoes. Do not use vacuum cleaners that are worn as the attachments or the wheels may scratch the surface. Bath and other wet areas In the bath or other wet areas, using a squeegee after each use can minimize soap scum. To remove soap scum, use a non-acidic soap scum remover or a solution of ammonia and water (about 1/2 cup ammonia to a gallon of water). Frequent use of an ammonia solution may eventually dull the surface.

Vanity top surfaces
Vanity tops may need to have a penetrating sealer applied. Check with your installer for recommendations. A good quality marble wax or non-yellowing automobile paste wax can be applied to minimize water spotting.

Food preparation areas
In food preparation areas, the stone may need to have penetrating sealer applied. Check with your installer for recommendations. If a sealer is applied, be sure that it is non-toxic and safe for use on food preparation surfaces. If there is a question, check with the sealer manufacturer.

Outdoor pool & patio areas
In outdoor pool, patio or hot tub areas, flush with clear water and use a mild bleach solution to remove algae or moss.

Do’s and Don’ts
– Do dust mop floors frequently
– Do clean surfaces with mild detergent or stone soap
– Do thoroughly rinse and dry the surface after washing
– Do blot up spills immediately
– Do protect floor surfaces with non-slip mats or areas rugs and countertop surfaces with coasters, trivets or placemats
– Don’t use vinegar, lemon juice or other cleaners containing acids on marble, limestone, travertine or onyx surfaces
– Don’t use cleaners that contain acid such as bathroom cleaners, grout cleaners of tub & tile cleaners
– Don’t use abrasive cleaners such as dry or soft cleansers .
– Don’t mix bleach and ammonia; this combination creates a toxic and lethal gas. sealing and maintenance

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Grout Sealing:

Always follow manufacturer’s instructions on the specific sealer being used.

Some sealers breath naturally so a “still wet” installation can be allowed to dry out even after the sealer is applied. However, some sealers lock in the moisture as they lock out the stains, so make sure which type of sealer you are selecting and the proper technique of application.

Your choices in grout sealers are a topical sealer that can offer a wet look, or a penetrating sealer that has a natural look, which protects the grout but does not change the look of the grout.

When sealing the grout there are various techniques to apply the sealer.

Always follow the manufacturer’s directions, but generally the best methods are to apply only to the grout joints and buff off any excess that happens to get on the tiles.

Another method is to apply all over the surface with a sponge or cloth and then buff off the excess with a terry cloth or cheesecloth rag.

Some sealers protect against everyday dirt and minor staining elements; others protect against harsh staining elements like hot grease. Look for warranties and protection information on the label from the manufacturers.

A little time spent on this can save a lot of grief later.

Grouts can also be re-colored by applying topical coatings much like painting. There are special products made just for this technique and the best news is, they work! If you have damaged grout that is discolored, you can fix it.

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Grout Cleaning

Cementitious grout, as you may have observed, is porous – it can absorb a stain. Looked at under a microscope, there is a large surface area to absorb stains. For this reason, many owners choose to seal their grout … usually the better the sealer, the more the grout joint is protected. Even better, if epoxy grout is used, it is virtually as stain proof as the tile.

Removing stains from cementitious grout is similar to removing stains from clothing. The same cleaners you might use on clothes to get out a stain should also work on grout.

Keep in mind though, that grout is based primarily of cement and sand. Sand, like glass, is unaffected chemically by most cleaners. Cement is not; rather it is alkaline based and is dissolved by acids. As baking soda and vinegar react, so do grout and vinegar.

Accordingly, it is better to clean grout with an alkaline cleaner (Spic and Span, Mr. Clean, etc.) than an acid based cleaner. There are also specialty cleaners available at most tile retailers that are designed for tile and grout. There are also cleaners with enzymes that attack stains similar to enzyme pre-soaks for laundry.

The same cleaner that works on the grout generally will work well on the tile. In fact, since the tile is usually so easy to clean, the tile can often be cleaned with water.

Just a few more important points: As the grout can absorb the soap as well as a stain – do not clean with oil or wax based cleaners – Murphy’s Oil soap, Pine Sol, etc. These products will leave a waxy or oily film in the grout… And, even good alkaline cleaners if not properly rinsed, will leave a sticky soap film. This usually attracts dirt. In fact, truly clean ceramic tile without any sticky soap film will stay very clean as tile does not tend to hold an electrostatic charge (which can attract some kinds of dirt).
The absolutely best way to clean grout is to apply the cleaner and then vacuum (“shop vac”) up the dirty water. This lifts the dirt off the joint. Apply rinse water and vacuum that water up. This lifts off any remaining soap film.

Just to mention it, there are tile installers that remove very stubborn stains on grout with an acid (like straight vinegar or a stronger acid). There they have elected to dissolve the top layer of grout molecules so the stain is no longer attached to anything. While this works, it is not recommended by the grout manufacturers – needing to regrout is sometimes the result. Also, extreme care should be used when handling any acids.

Should you be unable to get your grout clean through conventional methods, you may also want to try steam. Some stains that do not respond to conventional cleaners will come clean when subjected to pressurized steam. As a last resort, some installers elect to cut out the grout and regrout. This is possible although care must be taken to not damage or loosen the tile. Generally it is not possible to grout directly over the old grout without cutting the old grout out. The same contaminants that made the old grout dirty may prevent new grout from sticking properly.

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Cracked Grout

There are many things that can cause excessive deflection in your subfloor (and consequent cracking in the tile) or you may have a perfectly sound subfloor but not have prepared the floor properly for tile.

Here are a few of the most common questions:

1) Is the subfloor plywood over joists 16″ on center? If not, has the installation system been designed to work with the actual type of subfloor present?

2) What is the span of the joists? – Are they suitably sized for the span to achieve the L/360 deflection standard under the expected live and dead load? Are there any cracked, rotted, or termite damaged joists?

3) Was the subfloor screwed to the joists – is there any possibility of movement between the subfloor and the joists themselves?

4) Does the thinset used match the conditions present (was a polymer additive used and if so was it appropriate for the subfloor?)

5) Was the thinset coverage satisfactory? What was the notch size of the trowel used?

6) Were expansion joints used in the installation to allow for normal movement

7) Are any dimensionally unstable or questionable materials also in the tile/subfloor/joist sandwich? How about cushion vinyl, luaun, water-soluble patching compounds or mortar materials.

8) Were all layers present installed according to the applicable ANSI standards?

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What causes cracked or loose grout?

There are several things that can cause cracked grout and we would be guessing as to the cause. It could be that a field inspection is needed to determine why your grout is cracking.
Typically the most common causes are as follows:

1) Excessive deflection in the substrate – this movement can cause the grout to crack, and if sufficiently severe, can cause tile to crack.

2) Grout that is insufficiently packed into the joint. This most often occurs with wall tile. If insufficient force is used while grouting wall tile, it is easy to “bridge” the joint where the grout does not penetrate to the back of the joint. This is especially true if sanded grout is used in joints narrower than 1/8″. The sand grains can easily bridge a narrow joint – in this case the grout may be only on the surface and have little strength.

3) Grout made with an excessive amount of water or polymer additive – the liquid that goes into the grout ultimately must evaporate (except for that consumed by cement hydration). This evaporation can cause pinholing in the grout and a weak grout structure.

4) Grout packed after cement hydration started. All cement based materials have a pot life – if water is added to the mix after the grout begins curing in the bucket, the grout will be sufficiently plastic to pack but will not cure into a hard homogeneous block – rather it will be crumbly and weak.
Does your installer have any idea as to the cause? The least likely cause would be defective grout. Some other possible things to look for:

a) Spacing of joists.
b) Type and size of floor joists.
c) Span of floor joists.
d) Direction of the plywood sheets and placement of gaps.
e) Were there gaps between the sheets of plywood?
f) Type of adhesive and coverage of that adhesive.
In some cases even the type of tile can affect this (high or low water absorption tile bodies can vary the methods and materials needed).

Therefore you can see this can be difficult to assess without an on-site inspection. Usually minimum requirements are 16″ o.c. (on center) joists (2X10 or better depending on span), 3/4-inch subfloor with 1/2″ underlayment (or backerboards made for tile). The plywood sheets should be run with the long side parallel to the joists (both layers). The top sheet should be installed so that the joints don’t fall over the lower layer gaps nor above the joists. The adhesive needs to coverage at least 80% in the dry areas. The grout should be very dry and well packed into the joints. The joints should not be flooded with water when they are being cleaned.

Joints cannot be “grouted over” successfully. At least 2/3 by depth of the old grout needs to be removed when replacing or repairing grout.

Generally grout fails because of movement of the substrate or improper mixing and installation of grout. A ¾”-subfloor with 3/8″-underlayment may not fail but it is marginal and could cause problems. Stapling the two layers together could be problematical. The best method is to screw and glue the two sheets together. The underlayment should be plywood designed for that purpose too not just any plywood will do.

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Lippage

Variation in the height of adjoining tiles is called lippage. This is defined in the ANSI (American National Standards Institute) standard A108 A-3.3.7: “Lippage refers to differences in elevation between edges of adjacent tile modules.”

The ANSI standard notes that the perception of lippage is influenced by many factors such as:

A) The allowable thickness variation of the tile modules when judged in accordance with manufacturing standards.

B) The allowable warpage of the tile modules.

C) The spacing or separation of each tile module, which would influence a gradual or abrupt change in elevation.

D) Angle of natural or manufactured light accentuating otherwise acceptable variance in modules.

E) Highly reflective surfaces of tile modules accentuating otherwise acceptable variance in modules.

Additionally, variations in the plane of the substrate will also affect lippage. In many cases, when tile is installed by the thinset method over an uneven substrate, the installed surface will not meet lippage standards.

The table below is the ANSI A108 guideline for identifying acceptable lippage – note: any inherent warpage of the tile may add additional acceptable lippage.

Tile Type Tile Size Joint Width Allowable Lippage
Glazed Wall/Mosaics 1″ x1″ to 6″ x 6″ 1/8″ or less 1/32″
Quarry 6″ x 6″ to 8″ x 8″ 1/4″ or greater 1/16″
Paver All 1/8″ to 1/4″ 1/32″
Paver All 1/4″ or greater 1/16″

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Mineral Deposits in white grout.
Generally there are a few possible causes for white residue on colored grout. When there is a whitish mineral residue on the grout, commonly this is caused by efflorescence. Similar to the white powder left in a drinking glass when a glass of water is left to evaporate, efflorescence is caused by minerals that are soluble in water being dissolved and transported to the surface of the grout as the water evaporates.

Typically, the minerals originate in the cement slab below the tile or in the ground below the slab.
Except in the rarest of cases, efflorescence does not occur from the small amount of minerals in water used to wash a floor. Nor when tile is installed with thinset (tile cement), are there enough soluble salts in the thinset to cause efflorescence.

Occasionally, when tile is installed over a thick mortar bed, the mortar could provide a sufficient amount of soluble salts to cause efflorescence but only if moisture is regularly passing through the mortar bed.
The next question must be where is the water coming from? Similar to the glass of water analogy, it takes a lot of water to dissolve enough minerals to be noticeable. As previously stated, typical cleaning does not provide enough water to cause efflorescence. Even saturating the grout joints with water during periodic cleaning generally does not cause efflorescence.

In exterior installations over concrete, rain can cause efflorescence over time when other conditions are right – especially with poorly compacted or porous grout.

More commonly, there can be moisture in the ground below the slab that is always evaporating. Even when a vapor membrane is installed below the slab, penetrations in the membrane may allow sufficient moisture to cause efflorescence. This moisture, invisible to eye, is steadily traveling through the slab, the tile cement, and the grout. More efflorescence will be observed if the concrete and grout are more porous.

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Porcelain Vs. Non Porcelain Tile
Porcelain tiles are also ceramic tiles. Rather, the question should be, “What are the differences between porcelain tiles and non-porcelain tiles?”

Porcelain tiles are typically made with “porcelain” clays that have specific properties. Typically, these tiles are dense and by definition, they have water absorption of 0.5% or less. Non-porcelain tiles have water absorption greater than 0.5%.

Because porcelain tiles have a low water absorption, they are usually frost resistant – although, not always. To know if a tile is frost resistant, you should check the manufacturer’s literature.
There are also many non-porcelain tiles that can be used in freeze thaw environments and that are manufactured with properties similar to porcelain tiles.

There are both glazed and unglazed porcelain tiles – it is important to know the difference, as the glazed variety is usually a little easier to clean. Typically, glazed porcelain tiles have filled in microscopic holes that could be present in the unglazed tile. On the other hand, unglazed porcelains may have better slip resistance.

Non-porcelain tiles cover a wide range of properties – typically they are glazed (although unglazed quarry tile is the exception) and the glaze layer can be extremely durable. However, as there are differences from one glaze to another, it is important to check if the tile has been tested and to make sure the glaze hardness is suitable for your application.

In general, non-porcelain tiles are easier to bond to the floor and usually easier to cut. Porcelain tiles are harder to bond and harder to cut. While this can be relevant to the tile installer, it generally makes little difference to the end-user, so long as the installer uses the right materials.

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Thru Body Tile
Some people refer to unglazed porcelain tile as “through body” – i.e. the color on the top goes all the way through. Even in extreme applications, these tiles tend not to show wear as the porcelain is quite durable (harder than granite) and the color goes all the way through.

Many glazed porcelains also have extremely good durability. Although the color in the glaze layer may be different from the body, the surface is usually sufficiently resistant to abrasion to not show wear in typical applications.

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Tiling Over Exterior Decks and Balconies
We are often asked about tiling exterior decks. The TCA Handbook contains two details for decks, F103 (Roof decks) and F104 (Balcony decks). Additionally, many manufacturers of setting materials also make roof deck drainage systems. Often, these proprietary systems are highly modified versions of the F103 system, allowing precipitation to drain away from the tile.

There are no backerboard systems in the handbook for exterior decks – however, under some circumstances and with appropriate waterproofing, backerboard manufacturers may authorize such an installation. For details, you will need to speak with manufacturers directly as such methods tend to be highly product specific.

Many issues must be considered when tiling exterior environments:

  1. The tiles must be rated by the manufacturer for exterior use. In addition to certain industry tests, such as freeze-thaw, crazing, and water absorption, the manufacturer also considers other properties of the clay body and how the tile was fired. Additionally, some manufacturers have proprietary testing protocols and field testing they use to further assess the suitability of tile for exteriors.
  2. Satisfactory exterior installations must be able to drain water from the system before it gets a chance to absorb into either the tile or the layers below the tile. Since most tiles are water impermeable, the only water that can get into the system goes through the grout joints or though the substrate itself. The installation and the proper slope to drain will determine the extent to which the system saturates itself and in turn its ability to remain intact over time in freeze/thaw or high temperature environments.
  3. The setting materials and substrate must also be appropriate for the exterior conditions present. Freeze/thaw resistant mortars and non-redispersible polymers are often necessary. Expansion joints must also be designed into the system to allow for the movement typical with large temperature variations and exposure to water.
  4. The system must be able to accommodate wind and snow loading and other building movement. Commonly, exterior forces acting on the tile layer can be much greater than a comparable interior job. Accordingly, the installation must be suitably rigorous – methods developed for interior installations are not necessarily appropriate for exterior installations.
    Remember that exterior tile systems over inhabited space need a waterproof substrate below the tile. Without such, water will be able to penetrate below the tile layer and could cause damage. Even when tiling over areas not over inhabited space, serious consideration must be given to controlling where the water will go and how it will affect the tile and substrate.

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Can I tile over existing ceramic tile?
This is done regularly where there is not a floor height or wall thickness limitation and where the existing tile is well-bonded. To insure a good bond to the existing tile, certain procedures need to be followed; these are described in theTCA Handbook for Ceramic Tile Installation in detail TR712 and TR-713.

Note: Not all thin-sets (nor polymer modified thinsets) are capable of bonding directly to tile – please consult the grout and mortar manufacturers specified for their recommended thinsets. Also, depending on the tile already installed, in some cases the tile must be mechanically abraded to insure a good bond – this is usually best determined with a “bond test”.

Caution: Mechanical or chemical abrasion to tile can release fine particles which could cause harm if inhaled or ingested. Mineral analysis of the tile and glaze should be performed before performing any operation. Appropriate saftey equipment should be worn at all times.

There are many labs including the TCNA lab that can provide toxic metals analysis as well as shear bond testing.

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Can I tile over other types of flooring?
Guidelines for tiling over other surfacing materials are covered in the Renovation section of the TCA Handbook. TheTCA Handbook detail that covers this application is TR711. When tiling over other surfaces always make sure to check with the mortar and grout manufacturers to find the right material for bonding to the surface in question.

The manufacturers’ of tile cement (thinset) have developed specialty formulations for setting tile that are designed to bond well to specific surfaces. However, as with all tile installations, the entire substrate below the tile is important – not only the layer to which the tile is bonded.

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Crack Isolation Membrane

What is reflective cracking?
Whenever tile is bonded to concrete, cracks occurring in the concrete can cause cracks in the tile layer – this is often called “reflective cracking”.

What about tiling over control joints?
The Tile Council of North America Handbook recommends that control joints in concrete carry through the tile. Clearly, this is an industry-approved, nearly foolproof, and very safe way of making sure that movement in the control joints does not cause a reflective crack.

Due to a lack of consensus in the industry regarding competing anti-fracture products and the standards of performance for such, TCNA does not, at present, recommend a method for tiling over control joints with an anti-fracture membrane. This is not to say this process will not work – it can if the right products and methods are used and the slab does not continue to curl.
If the slab does curl at the control joint (which is not uncommon), any curling that occurs after tiling may damage the tile.

Can you tile over control joints using an anti-fracture membrane?
Some manufacturers have proprietary products where they will guarantee a tile installation (when their products are used in accordance with their methods) over control joints, so long as vertical deflection does not occur. However, expansion joints must be used in the tile layer.

It is a frequent misconception that anti-fracture membranes allow you to eliminate movement joints – they do not. There always must be soft joints in the tilework to allow for expansion and contraction.
Typically the joints in the tile installed over an anti-fracture membrane must be placed near the joints in the concrete but not necessarily directly in line with the control joints.

What about tiling over small cracks in the concrete?
Even small shrinkage cracks in concrete can be dimensionally active; continued curing of the slab can cause these cracks to expand or propagate. This type of cracking can be easily avoided in the tile layer – either by installing the tile on a mortar bed set over a cleavage membrane (method F111 for example), or by installing the tile over a crack isolation membrane using a thinset method.

In the mortar bed installation, the mortar bed is not bonded to the concrete – rather it is isolated from cracks in the concrete by the cleavage membrane. This allows the tile to “float” over the concrete.
In the thinset installation, a crack isolation membrane is bonded to the concrete. Tile is bonded (with thinset) to the surface of the membrane.

What is an anti-fracture membrane?
The internal make-up of this membrane is such that movement in the concrete is not directly transferred to the tile. Although the membrane is bonded to the concrete and the tile to it, the membrane stretches where needed to prevent or reduce force transference. These membranes are either trowel applied or sheet applied. In many cases multiple components or steps are part of the system. Performance varies also – it is important to check with the crack isolation membrane manufacturer regarding their installation instructions and intended use.

Can roofing felt or scribing felt be used as an anti-fracture membrane?
Some contractors have used felt paper as an inexpensive type of anti-fracture membrane. Unfortunately, this type of installation generally does not provide suitable bond strength between the tile and the floor, does not hold up to moisture, and can promote fungal growth.

What are the uses of crack isolation membranes?
Products made specifically for crack isolation are sold for everything from isolating the tile from shrinkage cracks to tiling over control joints to protecting the entire floor from potential cracking in the concrete.

When used to cover the entire floor, many manufacturers will warrant the entire floor installation, including the cost of replacing and installing new tile.

As noted previously, it is a frequent misconception that anti-fracture membranes allow you to eliminate expansion joints – they do not. There always must be soft joints in the tilework to allow for expansion and contraction. Guidelines for expansion joint placement are given in the Tile Council of North America Handbook. The exact placement of expansion joints is a function of many items including exposure to sunlight and the range of high to low temperature, moisture, aging of the concrete (where relevant), structural movement, expected loading, and other design criteria. The manufacturer’s recommendations should also be consulted and followed.

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What is thinset mortar, dryset mortar or drybond mortar?
Thinset mortar is a blend of cement, very finely graded sand, and a water retention compound that allows the cement to properly hydrate. Tile set by the thinset method is adhered to the substrate with a thin layer of “thinset” cement. The terms thinset cement, thinset mortar, dryset mortar and drybond mortar are synonymous. This type of cement is designed to adhere well in a thin layer – typically not greater than 3/16th thick. For example, a 3/8″ notch trowel will produce a 3/16th inch thick coating after the tiles are pressed in to the cement. While very minor adjustments in height can be made, this method is not appropriate for adjusting the level or flatness of a surface – rather the tile will follow the plane of the substrate.

The American National Standards Institute (ANSI) defines the properties of thinset mortar in the A118.1 specification.

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Movement Joints, Expansion Joints or Control Joints

Why are movement joints needed?
Recognizing that tile is a facade, movement joints are needed to eliminate stresses that can occur between the substrate and the tile due to differing amounts of expansion and contraction.

Where should movement joints be placed?
The Tile Council of North America’s TCA Handbook recommends allowing for expansion and contraction in every tile installation. In small rooms, a gap at the perimeter of the room (often hidden by baseboard or shoe molding) is sufficient. For larger areas, the movement joints will be visible.

We can not specify the exact location nor frequency of movement joints as there many site related conditions that must be addressed – however, we do offer guidelines in Detail EJ171 in the TCA Handbook. It is especially important to note for interior installations, movement joints are placed more frequently when moisture or direct sunlight is expected. For exterior installations, the range of temperature from summer highs to winter lows must be considered.

Why do rooms with more sunlight need more movement joints?
The intent of the guideline regarding sun exposure is to recognize that areas that get warm (or wet) may experience greater amounts of differential expansion. If the areas exposed to sunlight are warmer than surrounding areas, movement joints should be used more frequently. If the tile surface is not appreciably affected, no accommodation is needed in the joint spacing.
Only the area subjected to increased temperature needs to have movement joints more closely placed, not the entire floor if elsewhere the floor is an even temperature.
What other things should be considered when determining spacing for movement joints?
Many things can subject the tile layer to shear forces in addition to temperature and moisture. The following is a partial list:

  • Continued curing of the concrete substrate can put the tile in compression
  • Deflection and vibration of the substrate – particularly with suspended slabs
  • Seismic activity
  • Changes in the plane of the substrate
  • Location of weight-bearing columns
  • Type of tile or glass

From what is a movement joint made?
Movement joints are filled with material that allows for contraction and expansion. For floor applications, urethane, neoprene, or polysulfide are most often used in traffic areas and silicone sometimes where traffic is not a concern. Traffic areas require a sealant with a shore hardness of 35 or greater.

Tented Tile

What causes tile to tent?
Tile heaved off the floor, or tented, and sometimes cracked is often a sign that movement joints were not used sufficiently. For tile over concrete, the curing of the concrete places the tile under compression.

Why do installations tent after a number of years?
How long it takes tile to tent is directly a function of at least three variables – the rate of concrete shrinkage, the shear strength of the thinset, and any expansive forces applied to the tile layer (heat for example). When the tile is poorly bonded, the tile can tent very quickly. If there is a strong bond, often the grout will compress significantly before the tile will lose its bond. Of course the type of tile is important as well – thinset has a harder time bonding to porcelain than most other tile. At the other extreme, I have seen a saltillo installation where the tile did not tent but rather spalled as the thinset and grout were stronger than the tile.

When tile fails with a loud report, this certainly indicates that a good bond was present. Only when the shear force exceeds the strength of the bond, will the tile let go. Frequently, either the tile or the concrete will be without thinset residue – as if the thinset was not applied correctly originally. Usually, if the tile is tenting years after the installation, this was not the case. Had the thinset not been applied correctly originally, the tile would have tented long before. Rather, it is important to consider that the cleavage plane will usually occur at the thinset transition – either the bond to the concrete or the bond to the tile, depending on the relative permeability and exact composition of each.

Hence, it is common to see one surface or the other sheared clean of thinset. Even in “explosive” failures where the tile cracks and “jumps” off the floor, usually one surface is free of thinset. Clearly a good bond had been established.

With organic bonding agents and some of the polymer-modified thinsets, continued shear forces degrade the bond over time. So even when tile tents without an explosive report, the original installation may have had sufficient adhesive.

In summary, every installation should allow for movement. Properly designed installations, where expansion and contraction do not create shear forces, should have no problem for the tile to stay well adhered.

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Oriented Strand Board (OSB) & Engineered Wood

What is Oriented Strand Board (OSB)?
OSB is a sheathing product manufactured from wood strands glued together with waterproof, heat-cured adhesives. Sheets are assembled in cross-oriented layers, similar to plywood. Many applications where plywood was used now use OSB. APA Voluntary Standard PS 2-92 specifies performance standards for OSB and plywood.

Is Oriented Strand Board acceptable as a part of a tile system?
The most current ANSI standards for tile installation (A108 – 1999) specifically exclude OSB. This is not to say that tile cannot be installed reliably over an OSB subfloor – however, there is significant debate in the tile industry regarding the conditions necessary for a long-lasting successful installation. The allowable ambient moisture level, extent of moisture related swelling before tiling, blocking and bracing and many other issues are still being debated. Each installation materials manufacturer has their own criteria and proprietary methods and requirements. Some backerboard companies will warrant installations using their products over OSB – however, their specific methods must be followed. Note, thinset manufacturers do not recommend installing ceramic tile directly to OSB. Refer to the TCA handbook for recommended systems that include OSB and follow manufacturer’s literature for instructions and cautions.

As with all installations, movement joints are necessary to allow for expansion and contraction in the tile layer.

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Steam Rooms

What are the requirements for installing a steam room in a residential or commercial application?
Installation guidelines are included in the TCA Handbook for Ceramic Tile Installation. Please visit the publications section to order the Handbook and ANSI Installation Standards.
Once you have picked out the materials for your installation you should consult the manufacturer for their proprietary application procedures and warranties.

Why do I need a membrane for a my steam room?
While glazed tile is vapor impermeable, the grout is not. In fact cementitious grout easily transmits water and vapor. It is highly likely in a steam room assembly that vapor can pass through the grout. It may also be necessary to insulate the wall cavity due to differential temperatures on both sides of the wall possibly causing condensation. Each manufacturer may specify a different application of the membrane. Always check with the manufacturer’s instructions.

Do I need a specific type of membrane for my steam room?
A waterproof membrane meeting the standards of ANSI A118.10 (as well as being rated and recommended by the manufacturer for the steam room application) should be used where ceramic tile is specificed (bonded directly to the membrane or otherwise incorporated into the system). Always refer to the manufacturer’s instructions and TCA guidelines.

This is not at all the same as waterproof coatings used on building foundations or as might be used on wood decking. Rather, this is a specialty membrane which bonds to the substrate and to which tile can be bonded.

If using cement board should the waterproof membrane go on top of or behind the board?
For thin-set applications (TCA Handbook detail SR614), you will see that a waterproof membrane can be installed on top of, or behind, the cement board. However, some manufacturers require that the waterproof membrane be used on the front and a vapor membrane on the back – this tends to vary according to the manufacturer.

A surface application of the waterproof membrane has the advantage that the cement board fasteners do not puncture the membrane.

Can gypsum wallboard or “dry wall” be used in a steam room?
There are no details in the TCA Handbook that incorporate gypsum wallboard in a steam room assembly. In general, the industry cautions against the use of gypsum wallboard in a steam room environment.

What kind of tile should be used in a steam room?
Virtually all tiles work will in steam room applications. However, as with all installations, it is worthwhile to discuss your intended use with a knowledgeable representative of the manufacturer.

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