Will Rain Ruin New Stucco? (Explained!)

If you have a lot of outdoor projects going on, any sign of rain is bound to get you nervous or raise concern.

Knowing how weather elements affect your building products is one of the many ways you can stay on top of things as a DIYer or builder.

In this article, we will be taking a look at the effects of rain on fresh stucco and what makes a stucco house finish last and turn out well.

So, pause your stucco application plans, sit back, and pay close attention to the below points because they are sure to help you attain a desirable wall finish.

Will Rain Ruin New Stucco

Here’s if Rain Can Ruin New Stucco:

Once stucco is applied to a surface, it needs at least 48 hours to cure properly. If rain gets on this product before the recommended curing time, you’re not going to like the outcome. So, rain and fresh stucco are not the best of pals.

Keep reading for a more detailed explanation of what rain can do to stucco.

Can Rain Hurt Stucco?

As you may know, stucco is a building product commonly used on exterior and interior walls. It can last for a long time if applied appropriately.

One of the many concerns you might have when using stucco on the exterior walls of your home is how it holds up when exposed to rain.

The degree to which rain affects stucco depends on how dry it is. Rain can only ruin your stucco finish when it is yet to cure properly.

  • If a considerable amount of rain gets on your stucco at the early stages of the curing process, there’s a high chance it’d slide off the lath beneath.
  • Stucco that is fairly cured might change color or appearance after rain exposure but won’t really change texture.

In some cases, rain can actually be good for stucco, light showers though, not heavy downpours.

The curing process of stucco requires water to be sprayed on its surface periodically for a good outcome, so sometimes, light rain can have positive effects on new stucco.

Another effect of rain on fresh stucco is a more extended drying or curing time. Your stucco’s color, appearance, or texture might not be affected in this situation. 

Once your stucco cures, it’s vital that you do not forget that the product is water resistant and not waterproof.

So, water can still be absorbed by this wall finish if it isn’t sealed, but it won’t sustain significant damage because the resistive moisture barriers beneath it would’ve set.  

How Long Should Stucco Cure Before the Rain?

There are two ways by which stucco can cure, the double-back method and the misting method.

Contrary to popular opinion, these processes can be initiated before and during the rainy season, but each period requires a different installation approach.

Stucco needs about 48 to 72 hours to fully cure before it can be exposed to rain.

It is not unlikely for rain to fall before the curing process is complete, so here are a couple of things you can do to avert any damage such incidences might cause.

  1. Cover Work Area with Sheets

At the first sign of rain, get some plastic sheets and proceed to cover your work area with them.

Make sure each sheet is super thick and can serve as an adequate shield from the downpour.

Properly secure the plastic sheets at a considerable distance from the new stucco to keep them from sticking to and ruining the wall finish.

  1. Add Solutions to the Stucco Mix

By adding solutions like Calcium chloride to your stucco mix, you can increase the product’s ability to withstand moisture or wet situations.

If you add a few cups of hot water when mixing in the solution, you can increase the potency of the mixture.

  1.  Do Not Prepare Stucco Mix in the Rain

Many of us already know this point, but it won’t hurt to mention it.

Avoid preparing your stucco mix in the rain. Mixing should be done in a covered and secure location.

What Happens When Stucco Gets Wet?

Four things can happen when stucco gets wet. You will find below a detailed breakdown of each occurrence. 

  • A Curing Process

There are two ways to cure stucco, but only one approach is widely used. This curing method is called surface-misting. 

Fresh stucco cured with surface mist must be lightly saturated with water two to four times a day for three or four days straight. 

This process causes the pH level of the stucco to drop and provides a solid and modifiable surface area. 

  • Damages or Color Changes

When stucco gets too wet at the early stages of application, damages or appearance alterations are bound to occur. 

Rain is not the only thing that can cause stucco to change its appearance or sustain damage. 

Saturating stucco with too much water when curing can also cause these issues. 

  • Thermal Shock

Fresh stucco that is hot should not be misted with cold water or exposed to cold water. 

Doing this can cause some distress in the material and result in a poorly cured or visually unappealing stucco wall finish.   

  • Nothing at All

Once your stucco is adequately cured, it can get wet without any detrimental changes occurring. 

There are thin layers of resistive moisture barriers underneath these products that enable water easily drain.

Does New Stucco Need to Be Sealed?

Both new and old stucco finishes should be coated with sealant routinely to increase the application’s durability.  

Sealant prevents water from seeping into the stucco and thereby slows down its deterioration rate. 

New stucco should be coated with sealant 30 days after it is applied to ensure that it cures properly and develops a strong and modifiable surface. 

Concrete masonry sealers work wonders on new stucco, while elastomeric paints are amazing protectants for old stucco wall finishes.

You should apply a new coat of sealant on your stucco wall every ten years. The interval varies with regional climate. 

Kindly note that stucco lasts pretty long and performs exceptionally well without sealant, so it is not a must to cover your stucco wall finish with this waterproofing material.

However, if your stucco has cracks and other irregularities on its surface, sealant might be your best bet at repairing or improving its appearance.


Rain affects new stucco when it is not fully cured.

Heavy downpours on stucco would most definitely disrupt the curing process.

Rain can cause the applied stucco to fall or slide off the lath or look unpleasantly different when it dries.

Despite the above information, wetting is still an essential step in the curing process of stucco. However, you are required to lightly saturate it.

Sealing new stucco is very much possible but it should be done 30 days after application for a pleasant outcome.

We implore you to check out the rest of our articles on exterior remodeling and wish you luck in your stucco application plans!