There are a lot of different types of grout on the market today. Sanded, unsanded, epoxy, presealed – it can be difficult to figure out what type of grout to use with what type of tile. It’s important to use the right type of grout, however, to ensure that the installation looks right and lasts as long as possible.

Glass is very fragile with a low tensile strength. This means that it does not flex in any way and will crack instead. Therefore the grout and caulk joints in the installation need to do the bending and flexing for the glass. So your grout joints will typically not be any smaller than 1/8-inch, regardless of the size or style of the glass tile.

At 1/8-inch the grout joint begins to get large enough that it becomes more difficult to fill with a standard grout. Sand is used in this size joint and larger to help fill the joint and make it more stable. Most people get a little hesitant about using sanded grout with their glass tile – after all, won’t the sand scratch the glass? In most cases, the sand will not affect your glass at all. There are a few types of color backed glass tile that do need an unsanded grout; if this is the case, you salesperson should indicate it to you at time of purchase, or the tile should have instructions that includes this information.

In addition to the size of the joint, your grout needs to be able to flex as much as possible to protect the glass. Therefore, latex additive grout is usually recommended. The added latex will help the grout to bend without popping out of the joint or harming the glass it surrounds.

Occasionally, epoxy grout can also be used with some types of glass tile. Epoxy is hard to spread and work with, but it flexes and it fills up grout joints without scratching the glass. If you’re worried about mold and mildew in your bathroom, for example, epoxy grout can be a good option to use.