A common misconception about tile and grout is that grout will somehow assist in stabilizing a tile installation. It does not. Unless you use epoxy grout it will add no significant structural elements at all.

So why should I use grout?

Grout is, structurally speaking typing, simply there to fill the spaces between tiles. That is an oversimplification, but it describes the grout’s function. More to the point, it is there to keep other things out of that space. Without grout the possibility of dirt, grime and all sorts of unruly, unwanted things may collect in the spaces between tiles. This may lead to not only unhealthy conditions, but also the chance of damaging your tile while trying to remove those things.

Does epoxy grout help stabilize tile?

If you’ve read any of my other posts regarding grout you have more than likely seen me state that epoxy is different. This subject is no exception.

Epoxy grout will actually add to the stability of your tile installation – to an extent. Epoxy will stabilize only the area between the tiles – the grout lines. It does not stabilize your tile enough to replace proper installation methods. This is not what epoxy grout is intended for.

A couple of reasons for using epoxy grout include the durability, ease of cleaning, and its ability to withstand staining. It is not intended as a product to make a sub-par installation correct.

How does epoxy help?

To the extent that it does stabilize your tile, it will only do so in the direction of the plane. If you think about tile on a floor epoxy grout will not (to any significant amount) stabilize your tile up and down. If you have a corner of your tile that does not have support beneath it, the tile will still crack eventually. It will take a bit longer because of the epoxy, but it will still crack.

If you have two tiles (not installed on anything) that are held together by epoxy grout between them you can grab each end and bust them over your knee like you would bust a baseball bat  (if you were insane) and they would break apart. You can not pull them away from each other and pull them apart – ever. That is the direction of the plane.

So although epoxy grout does add some stabilizing features to your tile installation it should not be used in that capacity.

Grout is an integral part of a correct tile installation but not in a structural way. As you plan your installation keep that in mind and treat your grout simply as an aesthetic part of your overall project. It will not assist in stabilizing any part of your tile. You should only be concerned about the color.

There are three basic materials used to set tile.

• Mastic
• Thinset Mortar
• Epoxy

For each installation there is a specific material you should be using. Before you start any tile installation you should ensure that the material you choose is suitable for that application.

Mastic

Mastic is a latex or solvent based adhesive that cures by evaporation. It is sold in airtight containers (buckets) and requires no mixing. It is ready to use immediately. It is suitable only for non-wet applications.

Mastic should never be used for showers or floors! Ever! When mastic gets wet the water will re-emulsify the adhesive base. This means that mastic turns to goo when it gets wet. Goo will not keep your tiles on the wall. Every one of the failed showers that I’ve ever replaced were installed with mastic.

With that said typed, mastic does have its place. It is “stickier” than thinset mortar which is why some prefer to use it – for everything. It should only be used in non-wet areas such as a backsplash, wainscot, or fireplace. An area that is not consistently exposed to water or moisture. It should also only be used on tiles smaller than 6 inches square.

Think about it like this: mastic is stored in a bucket with a lid on it. This keeps it from being exposed to air which would cause it to cure (dry). If you spread it on your wall and place a 12 X 12 inch tile on it, that’s just like putting the lid back on the bucket. It will never fully cure. If any moisture gets behind that tile with the mastic it will eventually re-emulsify and lose adhesion. That means is that your tile is going to fall off the wall.

There is also a product called “premixed thinset adhesive”. This product is pushed as a suitable material with which to set tile – it is not. It is only mastic with sand added to it. While sand does help materials from shrinking as it sets, it does not make mastic suitable for showers or floors.

Thinset Mortar

Thinset mortar is what you need to use for shower walls and floors of any type. It is sold in bags and needs to be mixed with water. Sound simple? It is. Referred to as thinset, mud, mortar, or a number of other things, it is a combination of sand, portland cement, lime, and other stuff that makes it the preferred setting material for elves everywhere.

When mixed properly (read the directions, no, really, read the directions) it is stable,  not compromised by water or moisture, and rock solid. Thinset must be mixed with water, allowed to slake, then remixed before use. Slaking refers to letting it set for a specific amount of time to allow the chemicals to interact and become workable.

Thinset cures through a chemical process, not by evaporation. Air is not required for it to set. It will cure in the bottom of a bucket of water, really. This means that no matter the density or type of tile you use it for, it will fully cure. No worries there. The tile will stay where you put it.

Unlike mastic, thinset will not be compromised by water or moisture. If it gets wets the thinset will remain cured and will not be reactivated. It’s similar to your driveway. The concrete on your driveway was mixed with water but it doesn’t turn to mush when it rains. It’s the same stuff.

Thinset mortar will be the correct setting material for nearly every application.

Epoxy

Epoxy is a chemical based glue that cures through chemical interaction. It is almost bulletproof and not user-friendly. To be frank, it’s a pain in the ass. It is usually a two or three part product which, when mixed together, form a very stiff, very thick putty-like substance. When cured it becomes a permanant part of whatever is attached to it. That’s great on the back of the tile, not so much if you get it on the front. Use with care, it is nearly impossible to get off of anything once it’s set.

There are not many applications which require the use of epoxy setting materials. Certain exterior applications need it, swimming pools, certain types of stone and glass tiles. While epoxy can be used for any application, only specific jobs actually require it. It’s expensive. I mean really expensive. If you don’t need to use it, don’t.

If you are unsure whether or not your product or application requires epoxy, just check the manufacturer’s recommendations. If it is required, they will make sure you know about it. You can also ask me, just leave a question in the comments. I’ll reply, I’m a fairly sociable guy when I’m not crawling around on a floor.

Which to use

The general rule of thumb is to use thinset mortar. Unless your specific application requires epoxy, thinset can be used. Anywhere you can use mastic you can use thinset instead. It is more durable, water resistant, and cheaper than mastic anyway. As far as I’m concerned, the only thing mastic is good for is a free bucket.

There are three basic types of grout available for your tile installation. They are:

• Non-Sanded (also known as Unsanded)
• Sanded
• Epoxy

Choosing the correct grout for your particular installation will not only complete the job correctly, it will also cut down on maintenance. Properly installed and sealed grout will last for the life of your tile. So which to use and when?

Non-Sanded (or Unsanded) Grout

Unsanded grout is made specifically for grout lines smaller than 1/8 inch wide.  This is a general rule. I use unsanded grout only in tile with grout lines smaller than 1/16″. Unsanded grout (all grout to different degrees) will shrink as it cures. The reason for only using it in smaller grout lines is the wider the grout lines, the more grout must be used to fill them. The more grout you have, the more it will shrink. If you try to fill grout lines that are too large the grout will shrink enough to pull away from the sides of the tile.

Unsanded grout is easier to work with, especially on vertical surfaces such as a shower wall, because  it is “stickier” than the sanded variety. You can spread it onto the wall and it will stick there while you force it into the grout lines. It is also much easier on the hands than sanded.  Although it is easier to work with, you need to make sure that the application for which you are using it is correct.

Sanded Grout

Sanded Grout is used for any size grout lines 1/8″ and wider. Although the specifications state unsanded grout be used in grout lines that are exactly 1/8″, you really should use sanded for them. It will ensure proper adhesion to your tile and guard against too much shrinkage. No, not Seinfeld shrinkage, grout shrinkage.

Sanded grout has fine sand added to it. This prevents the grout from shrinking too much as it cures. That’s why it is used for larger grout lines and should be used for the majority of tile installations.

If you have a polished stone such as granite, marble, limestone, and some polished travertine, you should be careful about using sanded grout. While sanded may be the correct choice for the size of grout lines, it may not be the best choice. Depending upon the polish of the stone the sand in the grout may actually scratch it. If you decide to use sanded make sure you test it in an inconspicuous area first to ensure it will not scratch your finish. Or use epoxy which would be a better choice anyway.

Epoxy Grout

Epoxy grout is the top of the line and best choice for any tile application. It can be substituted for sanded or unsanded grout.  It is more sturdy than both as well as being waterproof and stain resistant.

Epoxy is a two or three part chemical consisting of the base and the activator. With some brands the color is an additional part that must be added. Once the parts are mixed a chemical reaction begins. From that point, depending on the brand of epoxy, you have only a limited amount of time to get everything grouted before the grout becomes stiff enough to be unworkable. When it reaches that point, if you do not have everything grouted you are SOL.

To help slow the cure time you can mix your epoxy then put half of it in the freezer. The cold air will slow the chemical reaction and lengthen the working time. You can then work with the other half until it is all used. Clean it up, wipe everything down, then grab the second half out of the freezer and finish up. When you first pull it out of the freezer it will be, well, frozen. It thaws quickly, though, so should be workable within a few minutes. This essentially doubles the working time of your grout and ensures you don’t have to rush through it.

Since epoxy grout does not contain sand (or at least not in the classic sense of sand) it will not scratch your tile. If you have highly polished granite or marble that’s important.

Different brands of epoxy have different working times as well as some being more difficult to work with than others. The brand with which I have had the most luck and the only brand I ever use is SpectraLOCK from Laticrete. It has a longer working time than any other epoxy grout (at least any I’ve ever used) and is virtually stain proof. Please don’t take that to mean the you can grout a jacuzzi with it, fill it with cherry kool-aid, and expect it not to be pink (Don’t do that). It just means that for all intents and purposes it will not stain without concerted effort. In my opinion it is the best on the market.

The only drawback of epoxy grout would be the price. It is fairly expensive. When weighed against the upside, however, it is well worth it. Low maintenance demands and high durability of epoxy grout make it well worth the money.

Picking the correct grout for your application is a key part of a proper tile installation. If you choose incorrectly you could end up with a multitude of problems and headaches. Grout, chosen and installed correctly, will complete your tile installation and push it from a good tile job to a great one. Do not underestimate the power of the grout.