Stucco is one of the popular materials for plastering buildings as it is environmentally friendly, durable, low-priced, and offers aesthetic value. However, this combination of lime, cement, and sand is also notorious for its coarse texture and high porosity making it susceptible to easy staining. One such popular stain with stucco is mold. The mold appears on stucco as it does on virtually every other surface. The presentation of mold on the stucco may be in the form of black, green, dark-brown spots or hazy-looking discoloration.

Signs Of Mold On Stucco

It is only possible to understand whether your stucco is threatened by mold or not by being able to identify early warning signs. Mold often exists stealthily, hiding underneath stucco. Thus, removing the stucco wholly is one of the best ways that can allow you to see a mold attack. Often, by the time you notice discoloration or dark patches on your stucco wall, it means the mold infestation is worsening.

Some of the signs of mold on stucco relied upon by professionals offering stucco remediation services include:

• Dark spots or stainings on stucco walls
• Cracks, peeling, and damage of stucco
• Damp looking stucco
• Moisture on the walls of the basement
• Missing stucco chunks or chips
• Musty smell
• Rotting stucco wall

What Causes Mold On Stucco?

Since stucco siding is porous and retains water, it will trap even more moisture when the installation has not been done properly or the material is damaged. The excess retention of water and moisture by stucco provides the perfect habitat for mold living and growth. As well, the availability of trapped water is known to attract the presence and spur the growth of organic materials like plant life and dirt which the mold relies on for feeding.

Although stucco is a great siding option, as a homeowner, its attraction to mold is one issue you will have to constantly be prepared to deal with. Leaving your stucco exposed to mold attack means once it becomes a breeding ground it will become unattractive. Even more importantly, mold growth on or underneath stucco walls may result in even worse issues if the attack extends between the exterior of a building and the framing of the building.

How To Get Rid Of Mold On Stucco

In case you desire to eliminate mold and discolorations on stucco and are not dealing with extensive walls’ stainings, below is a general step-by-step process to follow.

I. Mold Remover Purchase

Purchase a mold-removing product of your choice from any available shop selling home improvement products. The mold and discoloration remover should be specially designed for use on an exterior surface and use ingredients such as acetic acid, known for killing microorganisms such as mold. Ensure you strictly follow the use directions supplied by the product creator.

II. Protect Yourself

It is strongly advised that you safeguard yourself from skin or lung risk to mold particles and the cleaning agent. Therefore, you ought to wear disposable rubber gloves, safety goggles, and even face masks.

III. Stucco Rinsing

A pressure washer comes in handy for saturating the stucco walls with clean water and discarding any existing dirt. Rinsing the wall should be done from top to down. Only use a spray tip nozzle with low force to avoid ruining the often fragile stucco siding.

IV. Mix the Stain Remover Solution

Pour the cleaning solution into your bucket. Ensure you adhere to the instructions, including if the creator recommends the addition of water for lowering the potency of the solution.

If you do not want to use bleach which is highly toxic, you can use the equally effective and safe home solution of mixing borax, hot clean water, and dish soap. In this case, you will need to pour two hot water gallons into your clean bucket and then add ½ cup of sodium borate (borax) and two tbsp of dish soap to the bucket water. Make sure there is uniform mixing of your stain remover by using paint sticks.

V. Application of the Mold Remover

Applying the removal mixture can be done by either using a sponge or a single pressure sprayer pump. The use of a sponge is best when the area for mold removal is not extensive.You just plunge the wipe into the solution, remove it and wring out any extra solution, and apply it over a limited mold area. Repeat that process of applying the solution using a sponge to other mold-infested parts. Have a ladder in place to work on the mold spots not reachable while standing. But, if you are using a pump sprayer, there is no need for using a ladder.

Spraying the cleaning solution should be done from top to bottom of the stucco walls.

VI. Give the Solution Ample Time For Penetration

Once you have finished applying the mold removing agent on the stucco walls, give it about 25 minutes, particularly if you are dealing with a problematic mold. That is necessary to allow the solution to penetrate to and remove deeply placed discolorations.

VII. Rinse the Wall Off the Cleaning Solution

Use the spray tip of the nozzle, which is of low pressure, and link it onto the hose of your pressure washer. Consequently, rinse your stucco wall off the mold removal solution, guiding the dirt and the solution from up to down. Ensure the wall does not have any remains of the mold remover. If there is still additional stucco wall discoloration, you can repeat the process of applying the cleaner and rinsing with a pressure washer.

Once you remove all the mold spots, allow the surfaces of the outermost stucco wall to wholly dry for about a day.

Prevention Measures

In case your home or building has used stucco siding, you basically have two choices to safeguard it from potential damage. The first option is to subject your stucco wall to regular maintenance. The other option, which comes when appropriate maintenance is not adhered to, involves siding replacement. The last option is an expensive affair that every property owner should strive to avoid.

For maintaining stucco siding, we strongly recommend:

• The installation of appropriately-sized downspouts and gutters for handling large water volumes. It is also best to make sure the water is not capable of spilling over or leaking in the seams, which can lead to siding saturation and susceptibility to mold and moisture damage.
• Scrutinizing and repairing windows flashing and caulk after every few years.
• Preventing the leaking of your roof by implementing regular maintenance.
• Making sure the landscape surrounding your property or home is angled in a manner enabling the flow of water away from your building. Proper grading (positive grading) allows the prevention of mold damage and basement water.
• Removal of trees adjacent to your stucco surface since they are notorious for prevention of airflow and sunlight from reaching your siding.
• Ensuring there is proper ventilation in your home, such as in the bathroom and kitchen, to discourage mold attack and growth in the crawl space and attic vents.

In conclusion, for your stucco home or property, mold will always pose a problem. If you ignore a mold issue, sooner or later, you will have to deal with consequential structural damage to your property and more costly repairs. Furthermore, understand that mold on stucco can negatively impact your health, particularly in regards to inducing allergic reactions and promoting respiratory damage. Luckily for you, it is possible to use the service of a stucco remediation expert to protect your walls from excess moisture and mold and fully benefit from this awesome, popular siding option.

Tim David

HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.