Choosing a grout for your tile project can be intimidating—the choices only seem to multiply. To suss out a grout’s type, look for its A118 standard on the package label or online data sheet. Premixed grouts don’t have this standard—yet.
These traditional, tried-and-true grouts come in powder form; they’re mixed with water or a water-based polymer, and harden as the cement reacts with it.
Where to Use It:
Use standard cement grouts (Type A118.6) on bathroom walls and other areas that aren’t likely to get wet or soiled by food. More expensive and durable high-performance cement grouts (Type A118.7) can be used on floors, kitchen backsplashes and countertops, shower enclosures, tub surrounds, and even steam showers.
Standard cement grouts are forgiving to use and inexpensive ($10–$14 for 25 lbs.). As the only type of cement grout with an unsanded option, it’s best for scratch-prone glass or polished stone tile. High-performance cement grouts ($48–$50 for 25 lbs.) set faster but are just as easy to apply.
They’re inflexible and prone to cracking, stains, mildew, and efflorescence (surface lime deposits). Must be sealed once they cure and periodically thereafter. Color range is narrow and may not be consistent when applied (this is less of a problem with high-performance mixes). Vulnerable to acidic cleaners.
These grouts fall into two categories: Two-part epoxy grouts (Type A118.3) and premixed, flexible grouts made with either acrylic or urethane resins.
Where to Use it:
Both types can be used indoors or out on almost any tile job, and never need to be sealed.
Premixed, flexible grouts
They come in ready-to-use, DIY-friendly buckets; nothing has to be added or mixed in. Unlike other grouts, you clean the joints as you go. Once cured, these grouts remain flexible, adhere well, and absorb very little water. The more expensive premixes ($50–$80 per gal.) offer greater durability and antimicrobial properties than less-costly formulas.
All premixed grouts are sanded and therefore may scratch polished-stone or glass tiles. They shouldn’t be used in steam showers because they soften in high heat and humidity. Urethane-based premixes turn yellow in the sun.
Two-part epoxy grouts
These grouts consist of two resins: when mixed together, they combine to create a grout that is stain-proof, waterproof, chemical resistant, and bonds tenaciously. Epoxies cure hard, yet retain some resiliency, and they are tough enough for steam showers and pools. Both sanded and unsanded mixes are available. This is the grout to use if you want a bright color.
Epoxies are not forgiving to use: their resins must be mixed in the proper ratio, and the speed with which they set depends on the temperature. (They harden quickly in warm temperatures and more slowly when it is cold.) They can yellow if exposed to the sun, and may stain porous stone. Epoxies are the most costly grout option ($9–$15 per lb.), one best left to pro installers.
Thanks to: Ian O’Connor, product manager, Custom Building Products