What is Grout?

what is grout
Posted On June 22, 2018

What is Grout? Now, this is an interesting question. The most intriguing aspect of the question is the sheer number of different impressions we have heard homeowners offer when trying to describe it. For example,

    • “the dirty stuff on the shower wall”
    • “the material coming up from our tile floors”
  • “what we have to scrub all the time”
  • “the cement between the tiles”
  • “gritty stuff on the floors”

what is grout

What is Grout?

Well, we guess you get the idea. Now let’s talk about what grout really is and rest assured that it is actually your friend. The Ceramic Tile Institute of America says that colored grout, what you are most likely to encounter, is “commercially prepared grout consisting of a carefully graded aggregate, Portland cement, water dispersing agents, plasticizers and colorfast pigments”. So, for the layman, what is important in that definition is the combination of cement, water, and colorant.

What is grout?
Marsala Classic Tile

For a more formal definition we can check Wikipedia’s version here:

“Grout is a dense fluid which is used to fill gaps or used as reinforcement in existing structures. Grout is generally a mixture of water, cement, and sand and is employed in pressure grouting, embedding rebar in masonry walls, connecting sections of pre-cast concrete, filling voids, and sealing joints such as those between tiles. Common uses for grout in the household include filling in tiles of shower floors and kitchen tiles. It is often color tinted when we try to keep it visible. And sometimes it includes fine gravel when we use it to fill large spaces.  Unlike other structural pastes such as plaster or joint compound, correctly mixed and applied grout forms a water resistant seal.”

What are the basic types?

  • We use unsanded grout when grout joints are 1/8” wide or less.
  • Sanded grout is the norm with grout joints greater than 1/8” wide.
  • Epoxy grouts will be found in more challenging installations such as when acids or oils are anticipated.

The joint, as referenced above, is the space between the tiles or stones. Please keep in mind these are only the basic types of grout.

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Why do we use grout?

There are a few more things to know. One of the frequent questions often people asks: “why do we use it”? There are three prominent reasons:

  • Ceramic tile and terra-cotta tile are two examples of materials that are fired in a kiln. Think of a kiln as an “industrial oven” of sorts. Continuing that analogy, imagine the tiles are similar to cookies in your oven. The size and shape that go in are not exactly what comes out. So, grout is what fills the open spaces, or joints, that are needed to align the imperfectly shaped tile. Please see the image above from our Reclaimed Terracotta Collection.

Reclaimed Terracotta

Reclaimed Natural Rectangle Terracotta Tile


Reclaimed Terracotta

Reclaimed Natural Hexagon Terracotta Tile


Reclaimed Terracotta

Reclaimed Natural Parquet Terracotta Tile

  • The grout also serves to bond, or adhere, the tiles more precisely in the overall floor or wall assembly. You know that your tile is installed in mortar or mastic on the back or downside. It enhances the strength by further bonding side to side.
  • There are situations where the grout and its joint add to slip-resistance. A classic example is a shower floor composed of 1” x 1” or 2” x 2” mosaic tile where this cementitious material every inch or two inches provides a lot of “grab”.

Let’s Talk About Color

To help further answer the question; it is wise to talk about color. The oldest solution is the gray joint color on the terracotta floor immediately above. Another approach is to blend it with the color value of the tile. Our Marsala Classic Tile clearly illustrates this. This is probably the safest and easiest.

Marsala Classic Tile - Baldosa Style

Catania Classic Glazed Ceramic Tile


Marsala Classic Tile - Baldosa Style

Palermo Classic Glazed Ceramic Tile


Marsala Classic Tile - Baldosa Style

Modica Classic Glazed Ceramic Tile


Lastly, is to contrast the color of the joint and the field tile. This idea may have a downside given that grout is usually “smeared” over the face of the tile in the process of working the grout into the joints. Consider what a black grout might look like if left too long on the face of your awesome white ceramic tile.

We hope this post has done a reasonable job of answering What is Grout? query. Thanks very much for reading!

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