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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 six 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.

  • The grout will crack allowing moisture to penetrate.
  • Where the grout is sufficiently strong, movement in the walls, floor, or countertop can damage the tile.
  • 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 three to eight 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.

    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?

    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. Iif 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:

    • Spacing of joists
    • Type and size of floor joists
    • Span of floor joists
    • Direction of the plywood sheets and placement of gaps
    • Were there gaps between the sheets of plywood?
    • 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 perpendicular 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.

    What is the standard for determining the size of a grout joint?

    We are often asked what is the standard for determining the size of a grout joint - can it be bigger or smaller - does it need to be a specific size, etc.

    There is a relevant standard in the ANSI A108/A118/A136.1 manual. You will see that it is not specific; however this is the only part of the standard addressing joint spacing.

    ANSI A108.02, Section 4.3.8 - Nominal centerline of all joints should be straight and of even width with due allowances for hand-molded or rustic tiles.

    In genera, there is not a specific standard for the size of a grout joint. However, there are many relevant parameters that should be considered.

    1. What is the amount of variation from tile to tile?
    2. Are the edges of the tile linear or irregular (e.g. "hand-molded")?
    3. How big is the tile?
    4. What is the surface of the tile; can it be easily scratched?
    5. Where is the tile being used?
    6. Is the surface lefvel?

    Ultimately, the project owner should choose the grout joint they desire, keeping in mind that a tighter grout joint will show more variation from tile to tile. Many people feel that a joint smaller than three times the average variation from tile to tile (or two times the maximum variation) tends to look irregular and poorly installed.

    Also, grout accommodates differences in the angle of the surface. Where the floor or wall is not level, the grout will slope from one tile to another. When tiling over a hump, the grout joint opens up; and when tiling across a depression, the top of the grout joint narrows.

    For cementitious grout, joints smaller than 1/8" generally should only be grouted with unsanded grout, and joints of 1/8" and larger should only be grouted with sanded grout. Joints larger that 3/8" usually need a more heavily sanded grout to accommodate the large joint.

    Some manufacturers sell a "wide joint" mix (for joints bigger than 3/8"), but you can make the same thing by adding coarse sand to regular grout. For the exact amounts to add, you should check with the manufacturer of the grout you plan to use.

    Generally, sanded and unsanded grout should never be mixed and absolutely never with marble or any other surface that can be scratched by the sand in grout (note: marble is a cut product, manufactured to extremely tight tolerances and usually designed to be installed with 1/16" spacing).

    Tile spacing is measured between tile edges - not from the top edge of the bevel on the tile. The majority of tile made today has a beveled edge and grout should not be installed on the bevel. The bevel is often a glazed surface which is intended to transition from one tile to another. On some tiles, the installer must "hand-tool" the grout to keep grout off the bevel.

    A common mistake is to set the tile too close. Often, the finished results look sloppy due to variations in the floor or wall and in the tile. Even small variations can throw off the pattern of the tile if adjustments are not made in the grout joint. Although 1/16" of an inch may seem unimportant (for example, on a 12" tile), it represents a 50% variation in a grout joint 1/8 inch wide. This would be immediately noticeable and unattractive.

    What is the standard for variations in grout joints?

    When evaluating grout joints, it is important to consider that the grout is used to adjust for differences in the following:

    • Variations in the size of the tile
    • Changes in the plane of the substrate
    • Changes in the thickness of the tile (often this applies to hand-molded tile)
    • Variations in the rustic profile of the tile

    The standards for the manufacture of tile allow for variation from tile to tile. While the standard details this exactly, it is not uncommon for some manufacturers to ship tile with about 3/32" difference between the largest and smallest tiles in a box.

    Grout must adjust for these differences between tiles so understandably there can be some variation in the width of a grout joint.

    Generally, it is advisable to use a grout joint at least two times the average difference between the largest tiles and the smallest tiles. A smaller joint will exacerbate the differences between tiles as the human eye can readily see very small differences as a percentage of the total grout joint. For example, while a difference of a 1/16" of an inch may seem small on a 12" tile, this is readily apparent compared to a 1/8" grout joint.

    As the plane of the tile changes, the grout joint allows for this change. Should tile go over a hump in the floor, the grout joint will open; when tile follows a depression in the floor, the grout joint will narrow.

    Clearly, grout joints also accommodate both changes in the thickness and profile of rustic, hand-molded tile.

    Perhaps due to these variables, there is not a numerical standard to which the tile grout joint must conform.

    ANSI A108.02, Section 4.3.8 of the ANSI A108 standard says, "Nominal centerline of all joints should be straight and of even width with due allowances for hand-molded or rustic tiles."

    ANSI A108.02, Section 4.3.10 addresses variations in the plane of the tilework. This section states, "Finish floor and wall areas level and plumb with no variations exceeding ¼" in 10 feet from the required plane."

    However, it should be noted, elsewhere in the standards the plane of the subfloor is required to be similarly flat.

    Tile installed by the thinset method is really a surface finish that will follow the plane of the substrate. As such, variations in the substrate will be reflected in the tile layer, unless additional leveling is performed.

    What is causing my grout to have variations in color?

    Uneven grout color is not normal, but there can be a number of things that can cause blotchy grout. Also, how uneven the color appears can be somewhat subjective. Certain color grouts are not as easy to control. The easiest colors to work with are the medium grays and beiges as opposed to bright colors, whites, blacks, etc. Since most grout is cement based, it tends to turn gray with time and cleaning. Grout sealers are now recommended to reduce this effect.

    Some of the things that can cause color variation include:

    1. Too much water added in mixing the grout.
    2. Improper cleaning of the grout and grout haze off the tile (usually by wiping too soon and with too much water).
    3. Leaving plastic spacers in the joints.
    4. Having the thinset adhesive fill part of the joint and showing through.
    5. Improper mixing of the grout by using an improper amount of water.
    6. Mixing partial bags (this is a problem if the colorant is not evenly distributed).
    7. Using grout from a bag that was previously opened (and gained moisture during storage).
    8. Adding water after the first mixing (rehydrating).
    9. Failure to slake the grout.
    10. Improper joint packing.
    11. Inadequate cleaning of the sponges.
    12. Using unclean water.
    13. Defective grout itself (this happens once in a while).
    14. Dirty tools or shoes that stain the grout (we have actually had that happen to us, where workers tracked in clay on their shoes).
    15. Foot or other traffic too soon over the joints. Curing time is on the bag but can be up to three days for some grout.

    Sometimes the tile itself can have a microporoisty (small pores in the tile body, especially with porcelain tile) condition that sucks the moisture out of the grout too fast or in an irregular pattern. In many cases it is hard to tell exactly what went wrong by looking at the tilework. I would suggest that you ask the tile installer what he or she thinks about the workmanship and techniques used. One can always remove the grout and replace it if that is the only acceptable solution.

    If you have some of the grout left, the TCNA lab can test the grout.

    Our subsidiary consulting company, TCA-Team, is available for site consultations and failure analysis on a fee basis, should you desire an investigation.

    The color of the grout in my shower is inconsistent and in some areas the grout is a darker color?

    Uneven grout color is not uncommon, although in this case, the darkening may be caused by water (more about that later).

    This is in part because some colors are more prone to uneven color than others due to the dyes used. Also, depending on the tile, it may be impossible to allow the grout to sufficiently cure for best color uniformity and still remove it from the tile. In other words, the grout must be removed before the color has a chance to set.

    However, there are many installation mistakes that can cause uneven color including improper mixing of the grout (typically by using too much water), mixing partial bags (this is a problem if the colorant was not evenly distributed), using grout from a bag that was previously opened (and gained moisture during storage), adding water after the first mixing (re-hydrating), failure to slake the grout, improper joint packing, using too much water too soon when wiping the joints, inadequate cleaning of the sponges, using unclean water, allowing traffic on the floor too soon, etc.

    Where absolute color uniformity is desired, epoxy grouts are often recommended (they are much more expensive though) as they cure and clean up differently from cementitious grout.

    Is there a standard that addresses color variations in grout?

    There are no ANSI standards that address color variations in grout.

    This is in part because some colors are more prone to uneven color than others due to the dyes used. Also, depending on the tile, it may be impossible to allow the grout to sufficiently cure for best color uniformity and still remove it from the tile. In other words, the grout must be removed before the color has a chance to set.

    However, there are many installation mistakes that can cause uneven color including improper mixing of the grout (typically by using too much water), mixing partial bags (this is a problem if the colorant was not evenly distributed), using grout from a bag that was previously opened (and gained moisture during storage), adding water after the first mixing (rehydrating), failure to slake the grout, improper joint packing, using too much water too soon when wiping the joints, inadequate cleaning of the sponges, using unclean water, allowing traffic on the floor too soon, etc.

    Where absolute color uniformity is desired, epoxy grouts are often recommended (they are much more expensive though) as they cure and clean up differently from cementitious grout.

    Unfortunately, with regular cementitious grout, there is little that can be done once the grout is in place except for attempting to use a grout colorant. 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 (or impossible) to color.

    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.

    Grout treated with a colorant also has a different texture than originally colored grout. On the plus side, grout colorants usually seal the grout in addition to changing its color. Typically, grout that has been treated with a colorant does not need to be sealed.

    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.

    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.

    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. 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.

    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.