Grout Outdoor Tiles in the Rain. 9 Things You Should Know

Grouting outdoor tiles in the rain isn’t as straightforward as grouting in dry weather. Thankfully, it’s still possible if you take a few precautions, use some additional equipment, and are prepared to wait. This article explains everything you need to know. 

How Long Does Outdoor Grout Take To Dry?

It takes outdoor grout at least 72 hours to dry. How long it takes depends on the prevailing conditions, such as humidity levels, temperature, and the type of grout. In extreme cases, grout can take 7 days or more to cure. 

According to a study by Josef Kaufmann, excess moisture impacts adhesion strength, and it interferes with the bonded structure of your grout, making it vulnerable. With this in mind, you should exceed the recommended waiting time if the weather is particularly humid. 

Epoxy-based grout is durable and can withstand wet conditions thanks to its waterproofing properties. It also doesn’t require a sealant, making it suitable for outdoor tiling in wet conditions. The average curing time for this grout is 24 hours, but you should consider exceeding this period to achieve the desired results.

What if My Grout Gets Wet Before It Dries?

If your grout gets wet before it dries,  it may swell, become soggy, or crumble, damaging the material and leaving your outdoor tiles vulnerable. 

Water can have a devastating effect on uncured grout, and the disintegrated grout will leave spaces and openings along the tiles. Rainwater will likely find its way beneath the tiles, eventually damaging them or leaving your tiling job to appear unprofessional. 

To solve this problem:

  • Step 1: Wipe the area to clear the soaked grout.
  • Step 2: Erect a tent to protect the site from further water exposure.
  • Step 3: Allow the site to dry.
  • Step 4: Apply a fresh layer of grout. 
  • Step 5: Allow the grout to cure as per the recommended guidelines.
  • Step 6: Remove the tent when the grout is completely dry.

Can Rainwater Damage Outdoor Grout?

Rainwater can only damage outdoor grout if hasn’t yet cured fully. Most cement-based and pre-mixed grouts require at least 72 hours to cure, and exposure to water before the curing period elapses can damage your grout and outdoor tiles.

Once the outdoor grout cures, there’s little chance of it getting damaged by rainwater. Outdoor grout types, such as epoxy and furan comprise non-porous materials that make them waterproof. According to Purdue University, water increases the cure rate in epoxy at low degrees of cure, making it suitable for outdoor tiling since it can withstand wet conditions. 

How Long Does Grout Take To Cure Before It Rains?

Grout requires between 24 to 72 hours to dry before it rains. The material used will also determine how long it takes to dry. 

Cement-based and pre-mixed grouts require the longest time, taking up to a week to cure. In contrast, epoxy and furan grout require the least time to dry, thanks to their composition and water-resistant properties.

Nonetheless, you should postpone your tiling project if you notice it’s about to rain, as this could ruin your efforts. After all, most grouting materials are usually prone to water damage before curing.

Can You Apply Grout on a Rainy Day?

You can apply grout on a rainy day, but the process can become messy if you don’t take extra precautions. You should erect a tent to keep the site as dry as possible and seal the area with non-permeable materials to keep water away. If possible, build a temporary fence around the site to keep pets and kids away, so they don’t interfere with the tiling project.

After grouting, keep the area under the tent until the grout cures. Depending on the material used, you may need to protect the site from water for one to seven days until the curing process is complete.

How Do You Dry Grout After Rain?

There’s no practical way to dry grout after rain because most grout materials are porous and absorb water. 

Once water finds its way to uncured grout after rain, it will likely cause it to disintegrate, leaving your outdoor tiles vulnerable to damage. You can apply a fresh layer of grout or clean out the gaps between the tiles before starting a new grouting process.

How Do You Protect Outdoor Grout From Water?

You can protect wet outdoor grout from water by covering it with a tent or a piece of loose tarpaulin. Cured outdoor grout doesn’t need any protection from water because it’s water-resistant and can withstand wet conditions without issues. 

Some DIY experts recommend using a grout sealer to prevent water from penetrating.

Does Sealing Grout Make It Waterproof?

Sealing grout makes it waterproof and stain-resistant. Grout sealant consists of non-porous compounds that prevent water penetration. After completing the curing process, you should apply grout sealer to your newly installed tiles. You don’t need a grout sealer if you’re using epoxy-based grout.

Proper sealing similarly protects your outdoor tiles from fading and staining caused by sunlight and rain.

Here are a few tips on how to seal grout the correct way:

  • Step 1: Wait for the grout to dry and cure.
  • Step 2: Clean the tiles to clear dirt and dust.
  • Step 3: Apply the sealant evenly to the tiles using a roller.
  • Step 4: Apply the sealer evenly to the grout lines using a foam sponge.
  • Step 5: Wait for about 10 minutes for the sealer to dry.
  • Step 6: Test with water to check the permeability of the grout.
  • Step 7: Reapply the sealer if necessary.
  • Step 8: Repeat these steps every 2 to 3 years to protect the grout and keep your tiles shiny.

When Should You Grout Outdoor Tiles?

You should grout outdoor tiles on a bright day with clear skies. The temperatures should not be less than 50°F (10°C) or more than 100°F (37.77°C) since grout is susceptible to extreme temperature changes. Allow for up to 72 hours for the grout to cure fully.

Avoid applying grout in wet conditions as it exposes your outdoor tiles to damage. The excess moisture might find its way between the gaps left by the disintegrated grouting materials and get trapped beneath the tiles, causing irreversible damage. 

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