Grout FAQ - Grout for Ceramic Tile and Stone

Even if you have the exact same grout as was originally used, it could still vary in color when installed. Color of the grout will vary depending on how much water is used during mixing the grout and then during cleaning the grouted area. The color will vary depending on the rate at which it dries from various conditions such as temperature, relative humidity, wind, and how absorbing the surface is to which it is being attached.

You can try to match the grout color and if it doesn't come out well you can get a grout colorant and paint the grouted area to try to better match it. Good Luck.

Updated: October 13th 2009

Do I use Sanded or Non-sanded Grout? - Which grout should you use on marble tile for the floor sanded or unsanded?

ANSWER - Deciding on whether to use sanded grout or non-sanded grout depends on the width of the grout joint and whether the tile surface is sensitive to abrasion.

Non-sanded grout is designed for grout joints 1/8" wide or less. Sanded grout is normally designed for grout joints 1/8" wide or larger. Grout joints over 1/2" wide need a heavier gauge blend of sand to perform well. 1/8" wide grout joints can use either one, but sanded grout tends to be more stable and doesn't shrink as much.

Soft polished stones or soft glazed tiles can scratch when being grouted with a sanded grout, so always test the sanded grout with the tile first to make sure it doesn't scratch it. Good Luck.

Updated: October 13th 2009

Grout Joint Widths for Granite Tile - Is there a standard size for grout width for granite floors? Our new boat has 1/4 inch and our old boat has very minimal, which looks much better. Thanks.

ANSWER - Grout joint width depends on how consistent is the size dimensions of the tile and how flat is the substrate it is being attached to.

Should always have at least 1/8" wide grout joint. Some precisely sized stone can be 1/16" wide under ideal conditions, but I don't recommend it.

Some installers will use a wider grout joint than necessary so it is easier for them to install the tile and compensate for the irregularities of the tile and the substrate.

Generally speaking gauged granite tiles are installed with a 1/8" wide grout joint if the conditions are adequate.

Updated: February 12th 2009

Changing the Grout Color - I want to change the color of my grout in my kitchen. I was told to paint it with acrylic latex paint, will this work? Is Hi-gloss ok to use?
You should not use a latex paint over your existing grout joints, because it won't provide adequate coverage over the existing color, nor will it last.

There are special products called "Grout Colorants" made for painting over grout joints that are epoxy based. There are several manufacturers of these products who match the colors of cement grouts for ceramic tile and stone. You can go to the cleaner and sealer resource section of this website for a list of some of the manufacturers. Aqua Mix Grout Colorant is one of the better known products available.

Be sure to follow their instructions of fully cleaning the grout joints before applying. Good Luck!

Updated: September 23rd 2008

Grout for Exterior Tile - We would like to install some tile over a cement pad that is outside but we are wondering if there is something else other than grout that we can use. Can we use cement that has sealer in it? What about silicon? Do you have any other ideas?
First of all you need to be sure that the ceramic tile or stone tile that you want to use exterior is freeze thaw stable. The tile should not have more than a 3% absorption rate. You could use a silicon for grout and it would work well to make those joints water tight. It is not normally done. The silicon would have to have a shore hardness of 35 to be sure that women's high heals won't penetrate it and cause a safety issue. I'm not sure how easy it would be to install and to keep the silicone clean. It would be relatively expensive to use silicone. You could also use an epoxy grout that is stain proof and is recommended for exterior use. At website see the company Laticrete and Mapei under installation products listed under Resources & Links. Epoxy is not normally used exterior and it is a lot more expensive to buy and install. Normally it is recommended to use a polymer modified or latex modified cement grout, and then to seal with a sealer. Good Luck!

Updated: September 23rd 2008

Grout Joint - We have difficulty to fix zero joint Ceramic because the worker do not have any tool to adjust the ceramic like ordinary one where we can use blastic with + shape in between ceramic. Because do you have same tool for Zero joint or any other methods, because we are looking for high finishing?
I never recommend zero joints, because there are movements that take place within the ceramic tile or stone. I have seen failures where the adjacent edges of the tile or the stone create pressure on each other due to temperature or moisture movements with the tiles, which then causes the tile or stone to spall at the edges.

Experienced installers do not need spacers to put between the tiles. They snap chalk lines and create grids to keep the tiles and joints in line. Good luck!

Updated: September 23rd 2008

Cleaning - How do you clean grout residue from tiles that were not washed sufficiently?

Depending on what type of grout you are using would determine what type of cleaner to use to clean the grout residue off the tiles. Also you have to consider how sensitive your ceramic tile or stone is to chemicals and abrasion. Always test an area out of sight to make sure it works for you.

For epoxy grout use a paint stripper or Goof Off or an epoxy stripper.

For regular cement grout you can use a sulphamic or phosphoric acid, carefully! You can try vinegar.

For a latex fortified grout there are some special cleaners you can get to help clean it.

Be careful not to rub too hard because you may scratch or chip the tile. If you use anything acidic be sure to flush it thoroughly after you are done. The acid can etch the surface of soft glazes and polished stones, so test it first.

For more information and specific cleaning products visit the Cleaning and Sealing Resource Page by clicking here.

Updated: September 23rd 2008

Epoxy Grout Color Change - We recently had porcelain tile with epoxy grout installed in our kitchen, dining room, half bath, hallway, laundry room and foyer. However, the epoxy grout is not the same color as what we had chosen -- it has a "muddy" look to it. We were going for a lighter biege color to accent the tile. Is there any kind of grout colorant that we might try to change the color of our epoxy grout?

ANSWER - There are epoxy based grout colorants that you can purchase to apply over an epoxy grout or a cement grout to change the color.

On our website under Resources and Links under Cleaners, Sealers and Treatments there is a list of manufacturers who provide grout colorants at http://www.ctasc.com/Resources_and_Links/Cleaners_and_Sealers/.

It is important to properly clean and prepare the grout for this application. Follow the manufacturer's directions closely. Good Luck!

Updated: August 19th 2007

Add more Grout over Shallow Grout Joints - I just purchased a house with ceramic tile. Whoever installed the tile didn't use enough grout between tiles. The spaces between tiles are very shallow. Can I fill these with more grout? It's been 3 years since installation.

ANSWER - If the tile grout joints that have been filled with a cementitious grout seem low it is not easy to make them fuller.

Generally speaking you would need to first cut out the grout joints with a diamond blade saw and then re-grout the joints after they joints are fully open and clean.

If you don't cut out the grout, then normally you need at least a 1/4" in depth to apply more cementitious grout on top. First you would have to thoroughly clean the grout joints and then you would need to use a latex modified grout (add latex in lieu of water to grout).

Using an epoxy grout over the cement grout will allow you to have a thinner application, but the epoxy grout is more difficult to use and more costly. If you used this method you would need to fully clean the grout and let it dry and then apply the epoxy grout.

Always follow the manufacturer of the cementitious or epoxy grout instructions. Good Luck!

Updated: June 24th 2007

Why Grout Joints? - Hi, Can You please tell me if the travertine tile should be set with a grout joint or no grout. I am have this installed in my home tomorrow and the installer is telling me he needs to utilize a small grout joint to lay the tile and tight is not possible. I was under the impression the natural stone should not have any grout between the tiles. I would appreciate any information you could give me.

ANSWER - All stone or ceramic tile installations should have a grout joint for two basic reasons. First reason is that tiles will vary in size to some degree and the grout joint allows the installer to compensate for those irregularities to some degree to allow for a straight grout line. The more the variation in size the wider the grout joint should be for the tile. That is why Mexican paver tiles have such large grout joints is because they tend to vary in size so much.

Second reason is that tiles will expand and contract to some degree due to thermo conditions, moisture conditions and various dynamic movements within the structure. The cement grout joint is much more compressible than the tile itself. If the tiles are butt up to each other then expansion within the floor can lead to spalling at the edges of the tile. It is normally recommended to not have a grout joint any more narrow than 1/8” so it can be fully filled with grout and be more stable. The stone industry standards do allow for a grout joint as narrow as 1/16” wide if the stone tile is especially precision cut.

Also consider that the smaller the grout joint width the more likely you will get lippage from two adjacent edges of tile, where one edge is higher or lower than the other. The industry standard for smaller width grout joints is that there can be no greater lippage than 1/32”.

Good Luck!

Updated: May 22nd 2007

Grout Joint Width - Is there a standard that lists recommended grout joint sizes for tile?

ANSWER - There is no standard per se for grout joint width. It is recommended to always have at least a 1/8” wide grout joint for floor tiles in order to be able to fill the grout joint full. What dictates what width the grout joint should be is how consistent the tile is in its facial dimensions. Irregular sized tiles need a wider joint to allow for a straight grout joint e.g. Mexican pavers with ¾”+ wide joints. Rectified tiles are very consistent in size so you can get away with a 1/8” wide grout joint. Normally on vitreous and semi-vitreous clay body tiles you can have a 3/16” or ¼” wide joint. Use sanded grout for joints 1/8” wide and larger. Good Luck!

Updated: February 23rd 2007

Darken Grout - How can you darken grout lines. I dont want to use a paint or stain. Someone at Home Depot said I could use half mineral spirits mixed with half linseed oil to darken the lines. Is that true?

The only legitimate way to alter the color of grout is to use a product manufactured and warranted for that purpose.

If you do not use a product that is manufactured for this purpose then you are doing it at your own risk.

There is grout colorant which is painted onto the grout to stain and seal it.

Historically surface type sealers can be applied to grout that will darken it and seal it. Penetrating sealers normally do not darken the grout. There are sealer enhancers that intentionally darken stone that would likely darken grout.

I have heard of using linseed oil, but I understand it never dries and can become a maintenance problem. I have heard that in Mexico they use diesel fuel to stain their porous grout and tile. Obviously these types of products have fumes and can be dangerous.

Good Luck!

Updated: February 11th 2006

Grout for Flagstone - What type of grout should I use for the flagstone on my driveway?

For grout in flagstone with varying thick and width joints you need to have a grout with a greater ratio of sand to cement. If you want a specific color and more consistency there are grout manufacturers who make a Saltillo type grout for wide joints over ½” wide.

If you make your own grout then use a 1:3 mix that is one part portland cement to 3 parts fine-graded sand (ASTM C144-02) and then damp cure. You can also find this pre-blended mix at building material suppliers.

Good Luck!

Updated: January 30th 2006

Epoxy Grout - Is epoxy grout preferable to sanded or unsanded grout for ceramic tile and stone tile on the interior of homes. Please list the advantages and disadvantages.

Epoxy grout has significantly greater bond strength and compression strength over cementitious grouts. It is also very stain resistant.

Sanded grout is meant for grout joints that are 1/8” wide or more. Non-sanded grout is meant for grout joints that are 1/8” wide or less. Most epoxy grout will barely fit in a 1/16” wide joint. Grout joints are meant to be fully filled for maximum performance.

Epoxy grout requires more effort and labor to install than cementitious grout. The epoxy sets up fast and doesn’t have as much adjustability nor as forgiving as a cementitious grout. Installers who are new to installing epoxy grout without a lot of practice tend to struggle with the installation.

Porous stone and unglazed tile or textured tiles need to be protected when grouting with epoxy. The epoxy can stain in some cases and it can be difficult to remove from a textured surface. Using a penetrating type sealer or grout release can provide added protection.

A bad epoxy installation is normally very rough, has irregular joints, and has pin holes.

The epoxy itself maybe stain resistant, but if the surface of the epoxy grout is rough it will tend to pick up dirt easily and be difficult to clean. The surface of the finished epoxy grout should be smooth.

If installed well, epoxy grout can be very beneficial. Good Luck!

Updated: November 16th 2005

Matching Grout Color - What are your thoughts about using acrylic paint over unsanded grout? We installed an absolute black granite tile floor and the grout turned out to look dark grey. We added colorants, used the blackest grout, etc. Now, to avoid a lawsuit we need to make this grout as black as the absolute black tile as we stated on the contract. We were told epoxy paint is too hard to keep off of the granite and that we should use an acrylic black paint.

I don't know of any acrylic black paint that would be recommended and would have any assurance to lasting.

Normally what is used is a grout colorant that is epoxy based and matches various grout colors. One well known grout colorant is made by Aqua Mix http://www.aquamix.com.

The blackest grouts are normally epoxy grouts that can be applied thin like Laticrete Epoxy grout http://www.laticrete.com.

There are special stone joint fillers made by Akemi http://www.akemina.com to match granite stones, but it is designed for filling tight joints.

No matter how you go about it, it will be tedious and a challenge. Make sure you sample an area for the client to make sure they will accept it before doing the whole floor.

Grout never matches the grout exactly. You should have said that you would try to match the stone as close as possible, but the grout color will not be an exact match and there may be shade variation within the grout.

Good Luck!

Updated: July 18th 2005