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FAQs
 

Problems with Grout

 

 

 

Problems with Grout

When do you use caulk instead of grout?
Technically, anywhere there is a change in substrate or backing surface such as the joint between walks and floor and wall joint, caulk should be used in place of grout since these surfaces move independently of each other. However, it is important to recognize and make the end user aware of some important points.
Often, installers use grout in place of caulk for these reasons:
1)  The caulk may not exactly match the grout color
2)  Even when the caulk exactly matches the grout color when installed, it may not match 6 months later (Caulk will "age" differently from the       grout.)
3)  Caulk will need to be maintained more often than grout
4)  Mold may grow more easily on caulk (except caulk treated with mildewcide) than on grout
5)  Acrylic caulks break down in horizontal wet applications - silicone, urethane, or multi-polymer caulks are better choices but can be       harder to apply
      However, when grout is used in place of caulk, the grout can cause structural and aesthetic problems:
1)  The grout will crack allowing moisture to penetrate
2)  Where the grout is sufficiently strong, movement in the walls, floor, or countertop can damage the tile
3)  Grout cannot hide corner cuts as well as caulk
      In summary, caulk is the better choice - but the customer needs to understand its limitations.

What is the difference between epoxy grout and mortar and conventional grout and mortar?
We are often asked about epoxy grout and mortar versus conventional grout and mortar.
Epoxy grout (meeting ANSI A118.3) is quite different from cementitious grout and epoxy emulsion grout. Made from epoxy resins and a filler powder, the grout is extremely hard, durable, and nearly stain proof. Often times the bond between tiles is stronger than the tile itself.
You might wonder why this type of grout is not used all the time. First, most installers find it harder to use than cementitious grout. Also, it has a more plastic appearance which, as with all matters of aesthetics, some people like and some don't. Also, it is much more difficult to shape and slope; this can be done easily with cementitious grout and is often needed to transition from one tile to another. It may also slump in the joint hours after the floor is finished because the grout becomes less viscous initially as it heats up and cures. Lastly, it generally takes days longer to cure and must be kept rigorously clean. And it can cost 3 to 8 times as much as cementitious grout.
There are even epoxy grouts on the market impregnated with Teflon that are both stain proof (nearly) and wipe clean incredibly easily.
It is also possible to smooth epoxy grout (with or without Teflon) before it cures in a way that leaves the surface with an extra slick plastic finish to which it is very difficult for dirt to adhere.
These "100% solids" epoxy grouts should not be confused with epoxy emulsion grouts which are a mixture of cement and epoxy resins (ANSI A118.8). Epoxy emulsion grouts are not stain proof and generally will absorb liquids and stains. They are more similar to polymer fortified cementitious grout (ANSI A118.7) but may have better chemical resistance than some polymer fortified grouts.
Epoxy thinsets offer greater bond strength and chemical resistance than polymer modified cementitious thinset. This performance comes at a price as epoxy thinset is much more expensive than regular thinset. Typically, they are only used to bond to difficult substrates or where extraordinary chemical resistance is needed.

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Why is my grout and tile cracking?
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.
Our subsidiary consulting company, TCA-Team, LLC is available for site consultations and failure analysis on a fee basis should you desire an investigation.

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Repair & Removal of Grout

How do you remove grout that is adhered to a tile floor?
Removing grout that is adhered to a tile floor can be difficult. The type of tile greatly affects the difficulty of grout removal; also, if the grout was polymer modified, it may be more difficult to remove.
In general, the more porous the surface, the better grout will adhere - conversely, grout is more easily removed from dense impervious tiles (e.g. porcelain).
To remove the grout, start with an alkaline cleaner and a nylon scrub pad. Make sure to check that the scrub pad is not damaging the tile. Normal floor tile will not be affected by a using a scrub pad, but some decorative tiles do not have the same surface hardness. It is best to check your decorative in a secluded area.
If the scrub pad is not effective, there are specialty cleaners on the market that chemically attack the grout. Typically these are weak acids. As with all acids, follow the manufacturers warnings carefully and use caution. Always check the tile in an inconspicuous spot first in case the cleaner affects the tile.
Again, these specialty cleaners will not affect most floor tiles - however, it is prudent to check.
Some tile installers use stronger acids that they carefully dilute. While experienced professionals can do this, there are great risks in doing so. There is the possibility of bodily harm as well as damage to the surroundings.

Can I paint over grout?
Changing grout color is more commonly done but again the results are generally not as good as the original item. The color in grout, unlike tile, comes from liquid dispersed pigments. Obviously, these are not fired but rather become part of the cement/sand matrix. Grout is usually colored with an epoxy paint made for the purpose and sold in tile shops. When the grout is new, has not been sealed, and the edge of the grout joint is neatly defined and when the adjoining tile surface is very smooth, sometimes good results can be achieved. However, if the grout is not porous (from sealer or dirt), or the adjoining tile is rough or absorptive, it may be impossible to get a satisfactory result.

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Can I correct the color of my grout?
When grout has been stained to the point that it cannot be maintained or returned to its natural color, you can return the grout back to near its original color or any other color through the use of a "grout stain". Some grout manufacturers make grout colors, others will recommend specific brands that they know work with their grout to correct color.
However, grout colorants work best with grout that has not been sealed. Grout that has been sealed, or has been washed with oil-based soaps (Pine Sol, Murphy's Oil, etc.) can be very difficult to color.
Grout Stains are epoxy-based products that are specifically designed to penetrate into the grout and seal the surface with a permanent color. Once the grout has been stained there is no need to seal it any further with a penetrating/impregnating sealer.
Prior to staining, the grout joint should be cleaned thoroughly to remove any dirt, oils, grease or sealers with a professional strength Tile & Grout Cleaner. This can be purchased from most Home Centers or through your local Professional Floor Covering Dealer.
The edge of the tile also makes a difference in the success of the colorant - tiles with well-delineated edges are easier to treat than tiles with a large bevel or textured edge. When the colorant is applied, some will get on the tile - the easier it is to remove from the tile (and the better it sticks to the grout), determines in part how good the finished result appears.
Also, you will want to try a test area since grout treated with a colorant does not look the same as originally colored grout. On the plus side, grout colorants also seal the grout and protect it with an "epoxy-like" finish. Typically, grout that has been treated with a colorant does not need to be sealed.

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Cleaning Grout

How do I clean grout?

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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How can I prevent my grout from staining?
To prevent staining in the future, you should seal the grout.
Generally, sealer is a very good idea for cementitious grout (regular grout - not epoxy grout). For glazed floor tile it is not a good idea to spray anything on the tile - the glaze of the tile will be easier to clean and longer lasting than any coating. For unglazed tile, generally sealers are recommended although it is important to follow the recommendations of the tile manufacturer.
For cementitious grout, there are two broad classes of sealer: Penetrating sealer that chemically bonds with the grout and repels water (and water based stains) and topical sealers that coat the surface of the grout and repel almost everything (until they are worn off by foot traffic).
Each type of sealer has its advantages and disadvantages. Additionally there are hybrids on the market combining advantages.
In general the topical sealers are less expensive but give the grout a plastic appearance. Also they are subject to wear and tear and very sensitive to water in the grout while curing. As stated above, the plastic coating does block almost everything…until it is compromised by foot traffic.
The penetrating sealers are more expensive but also more durable. There are also penetrating sealers that repel oil based stains that are even more expensive. They can be applied on the grout sooner than the topical sealers, as they are usually vapor permeable. As they do not coat the grout (but penetrate in), they do not change the large microscopic surface area. While stains don't penetrate, they can be a little harder to remove (just a little) because the sanded texture of the grout hasn't been changed.

Loose/Cracked Tile My tile is bonded to a concrete slab, why do I have cracks?
While it is impossible to speculate on the exact cause of cracks without an inspection some reasons for cracking include but are not limited to: Whenever tile is bonded to concrete, movement in the concrete will cause cracks to occur in the tile layer.
Should cracks occur in the concrete, these cracks will "reflect" through the tile - this is often called "reflective cracking". Similarly, if tile is installed over a control joint (The Tile Council of North America does not recommend this), movement in the control joint will cause a crack in the tile. Even small shrinkage cracks in concrete can be dimensionally active where continued curing of the slab will cause these cracks to expand or propagate - if this occurs, the cracks will show through the tile.
This type of cracking can be easily avoided - either by installing the tile on a mortar bed set over a cleavage membrane, or by installing the tile over a crack isolation membrane using a thinset method.

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What is the difference in a mortar bed and cleavage membrane installation and a thinset installation using an anti-fracture membrane?
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/anti-fracture membrane is bonded to the concrete. Tile is bonded (with thinset) to the surface of the membrane. The internal make-up of this membrane is such that movement in the concrete is not directly transferred to the tile. The membrane compensates 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 manufacturer regarding their installation instructions and intended use.
Are there any other reasons I might have cracked/loose/hollow tile?
There are many factors that can cause tile to lose its bond to the subfloor. Losing bond to the subfloor has the potential to lead to cracking in the tile layer:
1. Expansion and contraction, especially if movement joints were not placed sufficiently in the tile layer - note for outdoor, indoor but sunny,      or moist installations, this is especially important.
2.  Poor quality thinset - especially where some shear forces (from expansion and contraction or deflection) are present
3.  Paint or lacquer overspray on the subfloor
4.  Sealer applied to the subfloor
5.  Moisture induced deterioration of the subfloor
6.  Delamination of the subfloor
7.  Excessive deflection
8.  Poor thinset coverage, thinset applied in "dabs", thinset used beyond its pot life, or thinset that was disturbed as it was curing.
9.  Moisture sensitive adhesive (affected by hydrostatic moisture or flooding)

If the floor sounds hollow does it mean my tile will crack?
Occasionally, a floor will sound hollow even when the tile is well bonded. This can occur when a mortar bed method is used and the mortar has delaminated from the supporting layer or when the subfloor itself is not sufficiently thick or well attached. Other systems that intentionally separate the tile layer from the substrate should be closely examined to ascertain if hollow sounds necessarily imply that the tile is not bonded.
While a tile floor with hollow spots is not ideal, it does not necessarily mean that floor failure is imminent. On the contrary, over concrete if there is no deflection in the floor; grout and gravity will help keep the floor in place (as long as there are sufficient movement joints in the tile and minimal shear forces). Over wood, floor failure is more likely - movement in the subfloor could cause grout to break away from the tile, compounding the instability of the flooring.

Can I inject epoxy under the tile to fix the hollow sound?
Some contractors have tried to inject epoxy to rebond tile without reinstalling it - while this may work in a small area, it is not practical over a large area. Further, any repair that does not address the cause of the failure may not last very long.

Porcelain vs Non-Porcelain Tiles


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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What is a through-body porcelain 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.

How is glaze resistance to abrasion determined?
Since 1999, U.S. and European manufacturers have been using the same testing method for determining glaze wear resistance - with a value of 4 (on a scale from 0 to 5) being good for almost all applications except the most abrasive and dirty environments. However, lower ratings are also fine depending on where the tile will be used and how much traffic and outside dirt (especially sand, because it is abrasive) will be present.
A rating of 4 can be achieved if there is no visible wear (under test conditions) after 2100, 6000 or 12000 revolutions of the test equipment. A value of three can be achieved by passing 750 or 1500 revolutions. Usually the product specifications will indicate which value was passed when the testing was done (for example, one tile might be rated Class 3, passing 1500 revolutions, another tile could be Class 3, passing.

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Services: Tiling Contractors, Installation, Floor Tiling, Wall Tiling, Shower Tiling, Grout, Ceramic Tile, Marble Tile

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