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How to Clean Stucco Walls [Guide]

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Stucco Wall and Roof Cleaning

If you are looking for a guide on how to clean stucco walls, remove black stains or how to remove mold on exterior stucco walls, this guide is for you.

Stucco is a great material for the exterior of your home, but cleaning it requires some special considerations. A stucco wall is naturally textured, so it can accumulate dust and grime deep in its cracks and crevices, making it hard to clean. To properly clean a stucco home exterior you will need to use the right chemicals and the right tools to get deep into the stucco without damaging it or causing new stains.

Important Considerations When Cleaning Stucco

Stucco is a great surface for the exterior of your home. It is beautiful, strong, and low maintenance. In the right environment and with proper care, a stucco wall can last 50 years or more with few signs of wear. Stucco is a cement product, so it is incredibly hard and resists damage. It also provides superior insulation from temperature and sound.

A stucco exterior is almost always textured, though the depth and type of texture vary based on architectural preference. The depth of texture ranges from the smooth Santa Barbara finish, to the deeply textured lace finishes that most people think of when they picture a stucco home. In any case, stucco is going to have enough of texture that it will hold on to dirt, dust, mold, and other stains much more stubbornly than traditional painted wood or vinyl siding.

In order to properly clean stucco, you will have to take into account the texture of the material as well as its tendency to hold at least some water. Because modern stucco is cement-based, it is also susceptible to cracks and chips, which will need to be sealed before any attempt at power washing. Pressure washing stucco walls with cracks and chips represent a risk of damaging the stucco and may allow water to penetrate the stucco finish, endangering the structure of the stucco walls and setting you up for some major damage down the road.

How to Remove a Stucco Stain

A stucco exterior can build up several types of dirt or stains. Different types of stains require different approaches to get them completely clean.

The most basic stain is just dirt, dust, and even bits of particulate air pollution that get stuck in the porous and textured stucco. This can cause the stucco to look grime and even change its color somewhat. Another type of stain comes from dirt and mud that are kicked up from the ground in a rainstorm or just from activity around the base of your walls. This type of dirt can be removed with a soft bristle brush or scrub brush and regular detergent or stucco cleaning detergent, whichever cleaning solution you prefer.

Sometimes stucco will develop what looks like black stains. While these stained areas may vary in appearance, they generally are not the same as just plain old dirt. Black stains can be caused by mold or algae that grow in the porous stucco. To get these out you will need to kill the mildew or algae first and then clean out the residue.

If there are nails, hooks, or other metal fixtures on the outside of your home, you may also get some rust streaking on your stucco. Rust streaks are easy to identify. They look like rust-colored tears streaking down from wherever the rusty culprit is. The rust simply runs down the wall with water from rain or any other source, leaving a rusty stain behind. While these stains are easy to identify, they can be tough to treat. However, with the right approach and some elbow grease, it is possible to clean them.

Preparing Your Stucco for Cleaning

Before you can clean your stucco walls, you will need to prepare the stucco so that you get the best possible results. The first thing to do is to inspect your entire exterior (or at least where you will be cleaning) for any cracks or chips in the stucco. A chip in the stucco could give way under strong pressure from a pressure washer and cause further damage. A crack in the stucco gives water from your cleaning a path into the wall structure behind your stucco. If water gets behind your stucco you could be in for some serious damage and expensive repairs, so be sure to note any cracks.

Luckily, stucco is a pretty forgiving material and chips or cracks can easily be filled in with plaster or stucco fill. Just make sure that the filling has enough time to completely dry before you attempt to clean it. After a week of dry weather, your repaired stucco exterior should be ready for cleaning.

Can You Power Wash Stucco Walls?

A power washer is a great tool for cleaning a stucco exterior. The pressure washer will help get into the tight cracks and crevices in the stucco texture that are hard to reach any other way. Just be careful that you don’t damage the stucco. This shouldn’t be a problem as long as you follow a few guidelines. 

Keep the pressure washer on a medium to low-pressure setting. Also, never bring the nozzle closer than 24 inches from the surface of your stucco. Finally, try to maintain a 45-degree angle approach with the pressure washer, so you avoid head-on pressure to the stucco.

Glass Geeks is your local San Antonio Roof Cleaning Professionals. So give us a call at 210-893-2356,  if you need professional help with removing mold from stucco, and make your house look amazing.

How to Clean Your Stucco Exterior

Once you have inspected your stucco, repaired cracks, and chips, and given everything adequate time to dry, you are ready to start cleaning. Using the right tools will make this part much easier. Electric power washers are available at most hardware stores. Gas-powered pressure washers can often provide more pressure and better overall cleaning. Both types of pressure washer are often available for rent as well as purchase at local hardware or home improvement store.

However, this is one area where nothing beats a Professional Stucco Cleaner. A professional-grade power washer is not generally sold to the public, and will definitely not be readily available for rent. A professional roof cleaning  company will have the tools, knowledge, and experience to get your stucco really clean with minimal mess and fuss. You should look for someone certified by Softwash Systems like Glass Geeks is.

The first step is to apply the detergent to the stucco. Detergent should be applied from the bottom up, overlapping somewhat to make sure you get complete coverage. The detergent needs to soak in for 5-10 minutes, but only works when it is wet, so you may need to add more detergent during this time. It is best to do your cleaning on an overcast day, so the detergent doesn’t dry too quickly. Also, you want to avoid leaving the detergent to dry on a wall for too long, because it can leave residue and stains. Instead, divide your house into smaller sections, working on one section at a time to treat it with detergent and rinse it before moving to the next.

Once the detergent has had a chance to work, it is time to rinse everything down. Start from the top and work your way down. This way you will capture the dirty water as it cascades down your wall and avoids having to rewash sections. Make sure to use plenty of water, so that dirty rinse water doesn’t get stuck in the pores of your stucco. If you use enough water, you should be left with nothing but clean water soaked into your walls, and it should dry clean relatively quickly.

How to remove mold from stucco walls

There are some spots that will not get clean with a simple detergent and rinse cycle. For these areas, you may need to use a brush and special treatments. A good rotating brush attachment for your power washer will make it much easier to scrub these stains clean without too much elbow grease.

For rust stains, apply a special rust removal detergent, followed by scrubbing and rinsing. That whole process may need to be repeated several times to get out a tough rust stain that has built up over months or years.

For stains caused by mold, mildew, or algae, you will need to kill the source of the stain before treating the stain itself. Simple oxygen bleach should do the trick. Mix the oxygen bleach powder with water according to any directions on the packaging. Apply the bleach solution liberally to the affected area so that the stucco is saturated and give it 30 minutes to work. The area should stay wet the whole time, so this is best done on a cool, overcast day. You can also apply more solution as necessary. Once the bleach has done its work, use a rotating brush to get out the stain and rinse as usual. Avoid using chlorine bleach, as it is poisonous to plants and will kill anything it accidentally spills on.

To prevent mold and mildew from coming back, a simple wash with detergent or even dish soap once in a while can clean off the food that the mold and mildew feast on. If the issue is algae, you can prevent regrowth by introducing copper to your wall. Copper is a natural biocide and inhibits algae growth. One way to introduce copper to your stucco wall is to install a thin strip of copper near the top of the wall. Every time it rains, the water that washes down over the copper strip will carry a minute amount of copper down over the walls, which is enough to deter algae growth.

To get your walls really clean, it helps to have the knowledge, experience, and toolkit of a professional power washing service that have years of experience in handling stucco cleaning. Call Glass Geeks today for your free quote.

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FAQ - Service Related To Article - H2

Does cleaning your roof damage it?

Yes, roof washing can damage your roof if done INCORRECTLY, which means you need to have the right training to know your roof’s material needs, the types of soils on the roof and the right equipment to execute. For example, a metal roof might allow a high pressure water without damaging but a shingle roof would easily stripped and severely damaged. However, to avoid damaging your roof in all circumstances, we use a low pressure water and a great soaping process that we call softwashing.

To get right to the point, residential home pricing starts based on the square foot size of the roof and ranges from $500 to $1500. From that baseline, prices increase based on the number of stories of the house (the difficulty of reaching the roof), the soil level (amount of soaps/time/etc needed to get it clean), the difficulty to walk on the roof (the pitch) and what material type is the roof made of (similar variables as soil level). Ultimately, the roof must be inspected for an accurate price.

Softwashing is a process of using low pressure water pumps and a special combination of commercial grade soaps. Certified softwashing systems use water-based, biodegradable chemicals that emulsify dirt and grime as well as sanitize the surface they are bonded to. The treatment lasts four to six times longer than pressure washing and uses one third of the water.

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