Why Are There Stains on My Stucco Walls?

Stucco results from a process of mixing concrete together with lime and sand. People have used this material for centuries to create a durable and beautiful exterior for homes in virtually any environment.

While stucco usually looks beautiful, it can become stained over time. Since there are multiple causes of stucco stains, it’s important to know more about these types of discoloration before you take any action.

What Causes Staining on Stucco Walls?

There are several different causes of stucco stains, and each type of problem can affect your stucco surface differently. Some types of stains may only be superficial, while others signal damage to the stucco that has caused the material to degrade.

Learning which type of stains are on your stucco walls will help you determine the best way to resolve the issue.

Dirt and Grease

Dirt and grease are the most likely causes of stucco stains on your home, and they are also the most superficial type of stains. In determining how these stains occurred, you should look at the exterior landscaping surrounding your home.

Shrubbery, trees, and other foliage can rub against your home or toss dirt against the stucco walls during a strong wind. You can eliminate this problem by moving flower gardens and shrubs farther away from the home.

Alternatively, a driveway can lead to grease stains on your stucco walls. In this case, stucco stains occur when vehicle exhaust coats the wall with grease and carbon. Oil and fuel on the surface of the driveway can also get splashed onto the wall during a rainstorm.


If your stucco stains look maroon or brown in color, they may have resulted from rust. There are several sources of rust that will cause this type of discoloration on stucco walls.

Commonly, fixtures on the home, such as metal drainage pipes, can cause rusty water to leak onto the walls. This usually leaves the discoloration behind or beside the metal fixtures on the home.

A second option is rust that’s occurring beneath the stucco facade. If your home uses foam board beneath a stucco facade, the studs holding the foam in place could be rusting. There might also be rusting of wires beneath the stucco surface. Either situation can cause visible discoloration on the surface of the stucco.

Mold and Mildew

Stucco mold remediation

As a homeowner, you already know that moisture and humidity can cause mold and mildew growth. These situations can lead to stucco stains that are greenish in color.

The mold or mildew stains on the exterior of your home can result from frequent rainy weather in humid temperatures. Otherwise, this might be a sign that there’s water damage or mold growth inside your home’s walls.


It’s relatively easy to identify soot stucco stains based on their location. When these black stains appear in close proximity to a chimney or exhaust vent, you can assume that’s the source of the stains. If you use a grill for cookouts, observe its location. Cooking too close to the home can leave black, greasy stains on your home’s walls.

Why Shouldn’t You Ignore Stucco Stains?

It can be tempting to ignore stucco stains since they might not seem to pose an immediate threat to your home. In fact, many homeowners do choose to ignore these stains, or the stains may occur on parts of the home the owner rarely sees. In any situation, unsightly stains on your stucco walls can be more than an aesthetic issue.

You’ll Lose Curb Appeal

There is a financial benefit to having stains removed from stucco. If you’re trying to sell your home, dark stains on the exterior walls can bring down your home’s value. It can also chase away prospective buyers who will assume there’s an underlying problem that’s causing the discoloration.

You Might Face Fines

Similar to losing market value on your home is the prospect of losing money to your homeowner’s association. If your neighbors complain to your HOA, you might face fines for not taking action to have the stains removed. Every HOA is different, so you should consult your association’s handbook to determine whether this is the case.

Extensive Damage Could Still Occur

Stucco damage

Depending on the type of stucco stains on your home, the problem might be bigger than visible discoloration.

For example, mold growth isn’t something that is confined to a small area. If it’s not removed, it can spread over time and degrade the exterior of your entire home. Additionally, mold represents a health hazard, so it’s something you will want to take care of right away.

Grease stains, rust, and soot can damage the stucco over time as well. You’ll know this is occurring if you see areas where the stucco is chipping. You might also see holes in the walls in areas where stains have occurred. Treating the area as soon as you see this type of damage can help you minimize your repair costs.

Why Should You Hire a Professional to Solve the Staining Problems?

Often, homeowners will try to remove or cover up stains by themselves, but this is usually a mistake.

Painting over a stain will leave the underlying problem to worsen, and you may need bigger restorative services to fix the issue in the future. Attempting to wash the stucco with a chemical-based cleaning solution can cause more damage than the stains.

The best choice is to hire a professional contractor with the tools and resources to fix the problem properly.

They will know how to remove the stain and address any underlying issues. If the stucco becomes damaged, they will be ready to repair it after removing the stain. Asking your contractor to fix the problem early on can save you on future repair costs while restoring the beauty of your home.

Turn to the Stucco Professionals

When you want to get rid of stucco stains, rely on Friel Plastering. Our team has the experience, knowledge, and state-of-the-art equipment needed to restore the beauty of your stucco walls. To get started, contact us today.