When tiling your bathroom floor or kitchen, grout makes a handy compound for filling the spaces between walls. But for the grout to do its work effectively — making the tiles stick together — you need to allow it ample time to dry.
Grout takes about 24-72 hours, on average, to dry. While the precise time depends on the type of grout, humidity levels, and whether the grout work is indoors or outdoors, the longer the drying time, the better the results. Grouting sooner halts the curing process, causing tiles to loosen and crack.
In this article, you’ll find more detailed information related to this topic, including the following:
- Why you need to allow grout to dry
- Whether grout dries faster in heat or cold
- Factors that affect the drying time
- How to speed up the drying process
- How long grout takes to dry to true color
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Why You Need to Allow Grout to Dry
Grout application calls for patience and precision. To apply tiles successfully, it’s essential to allow your grout to dry before applying a sealer or walking across the floor. Failure to let the grout set completely could disturb the grout, leading to problems such as weak joints, cracking, and the growth of mold or mildew.
When curing the grout, the most suitable technique to employ is a wet cure because it extends the standard drying time. When cured correctly, the grout turns hard and becomes water-resistant.
However, if it dries too quickly, the grout becomes soft and bears a chalky surface that’s water-absorbent. As it absorbs moisture, the grout swells, cracks, and eventually falls off.
Sealing the grout should also happen once the grout is completely dry. Once you install your tiles, give the grout a minimum of 48 – 72 hours to dry and cure. After they dry, you can touch up the grout, then allow for an extra 48- 72 hours before sealing the grout.
The sealer should take around 24 hours to cure, though some types can go up to 48 hours. Follow the manufacturer’s instructions to ensure you give it adequate time. To test whether your sealer has dried fully, sprinkle some water along the grout line.
If the grout is dry, the water drops should accumulate on the grout line. But if it gets absorbed, the grout isn’t fully dry, and you’d need to reapply the sealer as soon as possible.
Grout generally dries faster when it’s hot. The higher the humidity levels, the longer grout takes to cure; thus, it takes more time to dry during cold weather. For best results, install grout when temperatures are between 50-100ºF (10- 37.7°C) and after the bonding mortar has cured adequately.
On the same note, the amount of time your grout mixture takes to cure also depends on the powder and water temperature. Generally, hot water and powder grout mixtures cure much faster than cold ones. Still, a grout mixture composed of elements with high temperatures results in a shorter working time.
While it’s easy to meet the temperature requirements when performing indoor installations using modern HVAC systems, it’s not that easy to control temps with exterior projects. As a result, it generally takes longer for grout to dry outside than indoors because of the humidity, rain, snow, or cold.
Other than heat or cold, several other factors dictate the amount of time needed for your grout to set. These include the following:
The type of grout you choose has a significant impact on the drying time. For instance, standard cement grouts typically take a longer time (24-72 hours) to cure — especially during cold weather — while epoxy grouts take a relatively shorter period since they don’t necessarily require sealing.
Grout packaging typically contains all the information you need on usage, including recommendations on how long the grout needs to cure.
Let us take a brief look at the different types of grout available in the market:
- Cementitious grout. The use of cementitious grout is common in residential projects. Cement-based grout is easy to use and consists of water mixed with a sand-like mixture to form a paste. The grout also contains an additive that retains water, keeping it moist and slowing down the drying period for maximum hardness.
- Epoxy grout. Epoxy grout takes an average of 24 hours to dry. Though expensive, this durable grout is resistant to cracks, weather changes, stains, and chemicals. Also, it comes with epoxy resin and hardener, making it suitable for tiles that suffer exposure to harsh materials such as acid or grease. Since it dries fast, it’s relatively challenging to apply. Fortunately, it installs quickly as it doesn’t always require sealing.
- Sanded vs. unsanded grout. Sanded grout is most suitable for wide gaps (above ⅛”) or floor tiles because it hardly shrinks or cracks. On its part, unsanded grout is smooth and easy to apply, making it ideal for vertical surfaces that aren’t more than ⅛” wide.
- Urethane grout. These are pricey grouts that come premixed in buckets. Once you use the amount you need, you can save the rest to use later. If you’re considering using urethane grout in your shower, note that you might need to make special arrangements for your baths since it requires 7 days to cure.
- Furan grout. Furan grout consists of fortified alcohol polymers and takes about 24 hours to set. While drying, it forms a thermosetting resin resistant to strong chemicals and high temperatures. It’s commonly used in quarry tile, brick pavers, and industrial settings like commercial kitchens.
Another factor that impacts the time it takes for grout to dry is humidity. For instance, bathroom grout takes longer to dry than kitchen grout, while grout applications in tropical climates take longer compared to those done in desert climates.
The moisture content in the air slows down the grout’s drying and hardening process. Therefore, you need to allow for additional time before attempting to walk on the tile.
So, if you’re installing bathroom tiles, for instance, wait for 2 to 3 days, seal, allow the seal to dry as per the manufacturer’s guidelines, then use the shower.
Indoor plants like the lily or philodendron release moisture into the atmosphere. This raises the level of humidity in your home, and as mentioned earlier, the higher the amount of moisture in the air, the longer it’ll take your grout to set.
As mentioned previously, outdoor grout takes longer to dry compared to indoor grout due to humidity, rain, and snow. While it can take a minimum of a day for grout to dry indoors, outdoor grout can take up to 7 days, even in fair weather.
To cure, grout undergoes a chemical reaction. This means there’s little you can do to speed up the curing process. That said, there are several things you can do to make sure that the curing doesn’t slow down owing to external factors, thus hastening the drying.
Here are some valuable tips and tricks to speed up drying when carrying out indoor or outdoor grouting:
- Check the weather. Before commencing your outdoor project, ensure that the minimum temperatures for the next 7 days will be about 50°F (10°C).
- Cover the area. To protect your outdoor grout work from extreme weather, make sure to cover the area tenting but allow for a foot of space for airflow.
- Minimize moisture levels. To reduce humidity indoors, switch on the AC, fan, or dehumidifier and get rid of indoor plants. The fan or AC helps to spread air across your floor or walls, ensuring they dry up.
- Use a faster drying mortar (or an admix designed to speed cure time).
- Protect high-traffic areas. If grouting a high traffic area, like the kitchen, cover it with blankets, then lay the area with plywood once the mortar sets sufficiently. Doing so won’t only provide a safety buffer, but it’ll dramatically minimize the force placed on the tiles.
While a hairdryer can help speed up the drying process, it’s not advisable to use this method to dry your grout. The grout will dry too fast and end up cracking. The best thing to do is to let the grout dry naturally.
By forcing your grout to dry faster than usual, you heighten its likelihood to weaken, loosen, crack and eventually fall off. This is because it doesn’t get ample time to cure and adhere properly to the tile. Besides, the heat from the hairdryer will only dry the surface, leaving the inside uncured.
How Long Does Grout Take to Dry to True Color?
Grout takes a minimum of 24 hours to dry. Usually, the manufacturer indicates on the packaging how long the grout will take. But if your package has no information, wait for at least a day or two for the grout to turn the right color.
Sealed grout often appears wet due to its sheen. But while applying grout sealer might darken the color of your grout a shade or two, it doesn’t change it.
Allow your grout to dry for about 3 days, then compare the color with the one shown on the packaging. Initially, the grout looks dark but continues to lighten after a day or two, depending on the temperature and humidity. By the third day, it should be uniformly colored with no light and dark spots.
Once the water dries up, grout goes back to its original color — the color of the dry powder. Note that if you use a lot of water when mixing the powder, it can dilute the color, resulting in a lighter-colored grout.
Color variation occurs because of uneven drying of the cement within the grout. If your grout doesn’t dry to the correct hue, you can apply a lacquer thinner to help lighten it and disguise uneven coloring. To get your grout to dry to the exact color you want, try the following:
- After installation, have your tile contractor use a dye to color your grout to your desired shade.
- You can decide to change the color of your grout lines — whatever the type — to your preferred color even after sealing.
- Customize the color by carrying out a spot test to ensure that the final color is what you want.
- To achieve an exact match and color uniformity when using darker shades, consider color sealing your grout.
Finally, it’s important to point out that grout tends to darken with time. This is particularly so for cement-based grout in high-traffic areas. Unsealed grout can also seem darker when wet, but the color evens out eventually once the grout cures completely.
However, if you notice your grout turning black, the most likely cause is washing the floor tiles with excess water and detergent. The dirt that gets washed off the floor usually accumulates in the grout joints, finally causing your grout to look dark.
Black grout could also turn grey if too much water gets used when cleaning up the grouting, thus diluting the concrete and colored pigment ratio. As it dries, the grout will have less color, meaning gray, the color of the concrete will become the prominent color.
You might also want to read: Groutless Tiles: Everything You Need to Know
Replacing your tiles can help spruce up your home in a big way. But to do this right and ensure your handiwork lasts for long, you need to ensure that the grout cures well. However, if you do a rushed job and walk across your floors too soon, the tiles will loosen and crack, plus you’ll have to re-do the work.
Grout application is a delicate process that needs precision and patience. If your DIY skills aren’t the best, consider hiring an experienced professional to save yourself the time and money of performing even more repairs.