Choosing grout for showers

A common question that we receive in Product Support is, “What’s the best grout for showers?” The greatest concern is moldy, discolored grout joints – so, how do you avoid the dreaded black grout joints in your shower?

Besides having an industry-approved installation with proper slope to the drain, your grout choice factors heavily as well. Improper drainage can result in moldy grout joints due to standing water frequently being left in the joints, creating an environment for mold growth. Your choice of grout can mitigate or improve this situation.

Choosing the best grout for showers

Let us discuss the types of grout that are available. There is the basic Portland-cement-based grout, which is the most porous and prone to staining – sealing this grout after installation is recommended.

Next, there is a newer-technology, cement-based grout that provides better water and stain resistance. Be aware, though, that this grout is fast-setting and requires a slightly different application approach when compared to standard cement grout. Ready-to-use acrylic grouts and epoxy grouts are other options.

To determine which grout is best for your application will depend on the type of tile or stone and expected use (for kitchen floors or guest powder rooms, for dry or wet environments). There are so many options that it can be confusing; however, MAPEI has you covered with whatever you choose.

Shower-grout options

Portland-cement grouts

Pre-blended, polymer-modified, Portland-cement-based grouts are the “old school” grouts that have been around for many years. They are available in sanded or unsanded (depending on the grout joint width). They are also the most porous, which means that they will absorb water and stain the most readily. Keracolor S Sanded Grout is used for grout joints from 1/8" to 5/8" (3 to 16 mm) wide. Keracolor U Unsanded Grout is used for grout joints from 1/16" to 1/8" (1.5 to 3 mm) wide. Sealing these grouts after installation is not required but is highly recommended – wait a minimum of 48 hours before sealing. One of our penetrating sealers that we recommend is UltraCare Penetrating Plus Stone, Tile & Grout Sealer.

All-in-one grout replacements for sanded/unsanded grouts

This option is the 21st-century grout. MAPEI’s Ultracolor Plus FA can be used in grout joints from 1/16" to 3/4" (1.5 to 19 mm) wide without having to switch between sanded and unsanded grouts – only Ultracolor Plus FA needs to be used. It contains a different cement when compared to Portland cement, a fine aggregate and pigmentation, among other components. Grouts such as Ultracolor Plus FA cure denser and harder than traditional grout, providing better water and stain resistance. To clarify, there is no sealer in these grouts, but you can still seal them for additional protection. These grouts have a fine aggregate (sand), so in some rare occasions they can scratch the surface of soft materials such as polished marble or glass. Always do a mockup or small test area before grouting these softer surfaces. While sealing is not required for any grout, if you wish to seal Ultracolor Plus FA, we recommend our UltraCare Penetrating SB Stone, Tile & Grout Sealer.

Ready-to-use grouts

These grouts are typically either acrylic or urethane and take the guesswork out of mixing – open the bucket, give a quick stir and start grouting. As with any grout, ready-to-use grouts have limitations. In some cases, you do not want to use them for irregular-shaped tiles or pebbles. Many ready-to-use grouts cannot be submerged, so they cannot be used in pools, steam rooms and spas. One positive attribute is that you get color consistency. With MAPEI Flexcolor CQ, the pigment is attached to the colored quartz (CQ) beads and then suspended in a clear acrylic base. You cannot wash away the pigment like you can with cement-based grouts. If you wish to seal MAPEI Flexcolor CQ, a water-based penetrating sealer – such as our UltraCare Penetrating Plus Stone, Tile & Grout Sealer – is required.

Epoxy grouts

Epoxy grouts are the best option for a shower – they are the most water- and stain-resistant of all grouts. Epoxy grouts are more expensive when compared to other grouts and require a qualified installer to apply them. They mix and apply very differently when compared to any other grout. In addition, epoxy grouts are so impervious that they will not even accept a sealer. An example of an epoxy grout that we produce is Kerapoxy CQ.

Ensuring a successful installation

As with any grout, there are specific cure times and cleanup processes that you can find on each product’s Technical Data Sheet on our Website at www.mapei.com/us.

We suggest calling Product Support before installing any of our products – we are always available to help ensure a successful installation and are just a phone call away at (800) 992-6273!