If you have a project on the go and need to figure out how long your grout will take to dry – don’t worry – you are not alone.
While grout drying time varies depending on several factors, it generally will take between 24 and 72 hours to dry fully. This is a fairly wide range, which can be an issue if you’re trying to plan out a renovation or remodel.
Let’s take a closer look at the factors determining how long grout takes to cure, so you’ll have a better idea of how long your project will take.
The Difference between Drying, Setting, and Curing
While the terms are sometimes used interchangeably, there is a significant difference between drying, curing, and setting when it comes to grout.
Setting refers to applying the grout in between tiles.
Drying refers to when the grout’s surface has dried enough to feel dry to the touch. This does not indicate the grout is now solid enough to bear weight, and should not be confused with curing.
Curing is when compounds like concrete, epoxy, or grout achieve structural strength after the chemical process has had enough time to take place. The underlying process differs depending on the compound in question, but once sufficient curing occurs, the surface will be ready to use and bear weight.
Like concrete, as grout cures a chemical reaction takes place which causes moisture to bond with the cement. This is called hydration, resulting in the calcium silica crystals inside the grout doubling in size and bonding with the sand.
The grout-curing process begins even before the grout is set. Most grout requires resting the product for 10 minutes after mixing, which is the beginning of the curing process.
Factors Influencing Grout Dry Times
Grout dry times are influenced by several factors including the ambient temperature, humidity, and the type of grout in question.
Humidity plays a major role in the speed at which grout dries and cures. High levels of humidity mean the grout will continuously absorb moisture from the air, slowing down the drying and curing process significantly.
Likewise, dry environments will speed up the drying and curing process, as they’ll result in less moisture being absorbed by the grout.
If you’re trying to speed up the curing process, you can try using a dehumidifier to reduce the level of moisture in the air.
Another major factor influencing grout’s drying and curing times is the ambient temperature. Like concrete, high temperatures will speed up the chemical reaction and lower the drying/curing time.
This factor is generally easier to control than humidity and simply using the thermostat or a space heater will increase your grout’s drying and curing speed.
As you might expect, outdoor projects requiring grout are more difficult to adjust the temperature or humidity, and as a result, tend to take longer than indoor grouting jobs.
Type of Grout
Not all grout is made the same, and there are significant differences in drying/curing times when it comes to different grout variations.
Let’s break down several common grout types and see how this affects drying times.
Cementitious grout – also called cement grout – is a mix of cement, aggregate, and a water-retentive aggregate. This type of grout is closer to cement in application than normal grout – meaning it won’t dry out and harden immediately – which makes it easier to work with.
As a result, cement grout takes longer than other grouts to dry and cure – typically a full 72 hours. It also requires the use of a penetrating sealer to keep out mildew and discoloration.
Cementitious grout can be further broken down into sanded grout and unsanded grout.
Sanded grout uses larger sand particulate giving it a sand-like texture that you can feel when working with it. This grout is used for both wall and floor use, and due to the large sand size, it will only work for larger seams over 1/8”. It takes 72 hours to dry and requires the use of a penetrating sealer.
Unsanded grout, as the name suggests, does not use sand but rather uses fine polymers. It’s used for narrow seams like those found in showers, and walls. Like unsanded grout, it typically takes 72 hours to dry fully and requires the use of a penetrating sealer.
Epoxy grout is made from a combination of epoxy resin and a hardener. It has a very high bonding strength and is significantly less porous than cementitious grout. This means it won’t absorb water or develop mildew. As a result, it doesn’t require any sealer and is used for showers, backsplashes, and countertops.
The dry time for epoxy sealer is just 24 hours, so you can theoretically apply this grout and have the job completed the next day.
Furan grout is made from polymers comprising furfuryl alcohol and epoxy grout. It’s typically used in industrial applications, and like epoxy grout does not require sealer and has a shortened dry time of 24 hours.
The precise drying time of grout depends on several factors including the type of grout in question, the temperate, and the humidity. For indoor grouting projects, temperature and humidity can be controlled to some extent by using a fan or dehumidifier, however, oftentimes you’ll still need to wait a full 72 hours for the project to be done.