When beginning with tiling, it can be overwhelming when you realize the backsplash you want to cover with tile will require 2,300 tiny tiles. All of the tiles need to be leveled, perfectly aligned, allowed to cure the proper time, etc. If you are like I was before I had a couple of projects under my belt, your blood pressure is rising just from hearing this. However, it is comforting knowing that the base process is the same whether you install 4 or 100,000 tiles.
Although there are different products and some extra steps for some tiles, the base process remains the same and involves the same steps. This diagram shows an overview of the different layers involved when tiling.
This could be concrete, composite, drywall, or wood, and is coated with thinset (the adhesive compound that holds tile). The thinset layer could be applied on floors, walls, or ceilings. The key here is to have a surface the thinset and tile can stick to without the weight of the thinset and tile combination overcoming the sturdiness of the wall. (more on that later)
- Backerboard or Decoupling Layer
Backerboard will be described in more detail later, but it is an essential tiling material that can handle heavy weight of tile and does not deteriorate when coming into contact with moisture. A decoupling layer is placed between two different types of substrate, allowing for each to expand and contract at different rates without risking tile and gout cracks, or the tile lifting off of the thinset layer.
- Thinset Layer
If a backerboard or decoupler layer is used, another layer of thinset will be needed to allow the tile to stick to the board.
This is the my favorite part because I get to begin seeing what the end result of all the hard work looks like. The tile can be made of ceramic, porcelain, marble, quartz, limestone, granite, glass, or even pebbles.
Grout is used to fill the spaces between tile, which are called grout joints. Grout joints allow for hiding the slight variance in size between tiles, as well as allowing the tiles to slightly shift as expansion and contraction occurs. Placing grout in the joints adds rigidity to tiles, and is able to flex slightly with the movement of the tiles when expansion and contraction is occurring.
Material choice can be daunting with all the options available. Walk down the flooring isles at a local home improvement store or (even worse) a tile supply shop, and you will find dozens of options that seemingly do the same thing. This section helps alleviate that stress a little.
Tile Adhesive (Thinset)
Thinset is the adhesive that allows tile to stick to a surface. It is made of portland cement, very fine sand, and hydration compounds that helps stop the cement from drying too quickly when in contact with tile. Thinset is a type of mortar, but is technically not the same thing as mortar- meaning if you go to the tile supply store and ask for mortar, you will get mortar (like for laying bricks) instead of thinset. Mortar is a much thicker consistency, and is good for heavy tile or applications requiring a thick layer under the tile. In contrast, thinset is meant to be mixed to a marshmellow fluff-like consistency (thick enough to make peaks) and is only meant to be applied up to 3/16” thick.
Types of Thinset
Modified thinset is made of portland cement, fine sand, hydration compounds, and polymer additives. The key here is the polymer additives, which increases the thinset’s resilience against shock and movement. While that sounds great, there is a downside to modified thinset. It requires air to dry, meaning potential issues could occur if using between tile and an impervious membrane such as a decoupling membrane. A good example of when to use modified thinset is when attaching a decoupling layer to concrete or attaching tile to cement board.*
This is considered traditional thinset, and contains only portland cement, fine sand, and hydration compounds. A good example of when to use this type of thinset is when applying tile to a decoupler layer or other impervious membrane. The water in the cement causes a chemical reaction that cures the cement, and is not reliant on air for curing. This is why for cement applications like a post hole or sidewalk, the cement is supposed to be kept wet for the full cure time.
*Always follow manufacturer’s recommendations on which thinset to use for your substrate and tile. Failure to do so may void the warranty.
Mastic is an organic adhesive made from the mastic tree and provides an easy way for applying tile to dry walls. It is premixed, has a very long working time, and sets quickly. Because mastic is made from organic compounds, it has poor water handling ability and has the potential for re-hydrating when coming into contact with water. This means if used in wet areas such as a shower, the bond between the tile and wall could fail. Additionally, mastic is highly susceptible to mold. If grout is not properly sealed in an area exposed to wetness, mold will develop on the mastic.
I am not getting paid for mentioning this product, but mentioning AcrylPro is the easiest way to show an example of acrylic mastic. AcrylPro takes the best parts of mastic and gets rid of its flaws. AcrylPro is ANSI approved for intermittent wet use (such as shower walls) and is completely inorganic. It comes in premixed, ready to use tubs.
While acrylic mastic sounds great, I have seen it fail on shower walls. If using on an intermittent wet area, be aware there is still a potential to fail. Personally, I use thinset on shower walls for the added peace of mind that the installation will not fail. However, I do like using acrylic mastic for backsplash tile applications.
Grout is a flowable mixture made of portland cement, lime, water, and color additives. Why is grout important? First, it adds rigidity to the tiles. The second is that it allows a little flex without cracking from daily shifting of the substrate (backerboard) and wood studs. The third is it fills in the spaces required to be between the tile, stopping debris from getting in between and behind the tiles.
There are three types of grout: Sanded, Unsanded, and Epoxy.
Rules for Grout Choice
Choose Unsanded grout if the width of the joint is ⅛” or less.
Choose Sanded grout if the width of the joint is more than ⅛”.
Choose Epoxy grout if you need high stain, chemical, or UV resistance.
Unsanded grout is composed of grout without any added sand. It is stickier than sanded grout, and flows easier as well. Both of these factors make unsanded grout a great choice for walls, ceilings, and grout lines of less than ⅛”. This type of grout is also the best choice for polished natural stone or any other tile that could scratch easily.
Sanded grout is composed of unsanded grout with sand added. This type of grout is more durable than unsanded grout because the added silica reduces the amount that grout shrinks when curing. Silica is also the reason that sanded grout is less likely to crack than unsanded grout.
Sanded grout is the best choice for flooring and high traffic areas due to its durability. However, if using natural stone, glass, do not use sanded grout due to the risk of scratching the face of the tile. Also, if grout lines are narrower than ⅛”, there is an increased risk of the grout not completely filling the space between the tile.
Epoxy grout is not like sanded or unsanded grout. It is not made with cement but is made with epoxy resins, filler powder, and (depending on the product) a Teflon additive. According to the Tile Council of North America, this mixture of resins results in a grout bond that is stronger than the tile it is adhered to.
Epoxy grout is used in situations where waterproof, stain resistance, UV resistance, mildew resistance, and ease of cleaning are desired. These characteristics make epoxy grout a great choice for outdoor patios, showers, outdoor walls, countertops, and pools.
You may be wondering “Why isn’t epoxy grout always used if it’s so great?”. The main answer is cost. Using epoxy grout is an average of 8x the cost of sanded and unsanded grout. The cost difference may vary slightly between brands, but is very close to 8x when using grout calculators and comparing to all major brands of grout. If doing a large project that doesn’t require any of the benefits of epoxy grout, then the result would be a large, unnecessary increase in cost.
Caulk is the unsung hero of tiling. I have seen so many improper tile installations that look incredible except for the fact that caulk was not used where it should have been, and now there are cracks in the grout (or cracked tiles) on every wall.
Important Caulk Rule
Every change of plane needs caulk.
Explanation: A shower stall has 3 walls and a shower pan. There are 8 places that involve a change of plane and should be caulked instead of grouted (as seen in the above image). Anywhere that a flat surface stops and a surface at another angle starts, put caulk in that seam.
This is the most common tiling error performed daily by homeowners and professionals alike. Next time you’re in any commercial bathroom, take a look at the corners. Chances are if they’re not caulked, then there are cracks in the grout. This is because walls shift constantly, and each wall may not shift by the same amount. The caulk will flex and allow the amount of movement required by the walls.
If you are concerned with the caulk matching the grout, there are manufacturers that make grout and caulk that match. A little planning beforehand with grout and caulk choice will make for a great looking finished project.