How to Clean Stucco Siding
How to Clean Stucco Siding


A common building plaster for hundreds of years, stucco is also popular as an exterior finish for homes. The eco-friendly material is a mixture of concrete, sand, and limestone, and is generally applied over stone, concrete or metal meshwork.

Stucco improves the look of raw building materials while acting as an insulator from the elements. But the material is highly porous, which can lead to easy staining. Its fragility and tendency to crumble makes proper cleaning technique an important part of stucco maintenance.

You should clean your stucco at least once per year to prevent stains from algae, dirt, dust buildup, air pollution, and more. When cleaning, it's important to keep an eye out for any cracks, holes, or eroded areas. With aged, damaged or eroded stucco, water can easily get into holes or cracks that develop. This can cause mold, mildew, and other difficult issues, so be sure to repair any cracks or openings before cleaning.

It's relatively easy to repair minor damage such as hairline cracks or small chips without the help of a professional, but they should be consulted on issues of any greater magnitude.

Unpainted stucco is particularly susceptible to a type of algae growth called gloeocapsa magma, due to exposed calcium carbonate present in the limestone component of stucco. If your stucco has been painted, this isn't likely to be an issue. But black stains on your stucco are potentially an accumulation of this dead algae.

Those stains, and many others, are easily removed with Simple Green Oxy Solve House and Siding Cleaner. The powerful formula removes dirt and stains from mold, mildew, moss, algae, and more from a variety of materials. It cleans using peroxide to brighten and renew surfaces without bleach or any harsh or abrasive chemicals that can discolor or damage your stucco and is safe for use on vinyl, aluminum, stucco, wood, brick, and other types of siding.

Follow these basic maintenance steps to keep the best appearance and longest lifespan for your stucco.

Directions for Cleaning Stucco


Be sure to check your equipment warranty beforehand. Always follow the manufacturer's recommendation on proper cleaning practices.

Use caution when using a pressure washer and cleaning around openings like windows, doors, lighting, and plumbing connections.

Before cleaning: Protect nearby plants and grass, particularly during hot, sunny days, by rinsing them with water before and after pressure washing.

  1. Hose down the surface.
  2. Pour full-strength Simple Green Oxy Solve House and Siding Cleaner into your pressure washer detergent tank, or drop your siphon tube into the product bottle.
  3. Apply Simple Green onto the siding in sections from bottom to top, using a low-pressure setting and the 65-degree nozzle tip. Make sure your pressure washer nozzle is pointed at the siding in a downward angle, keeping a minimum of 18 inches from the surface to avoid driving water beneath or behind the siding. Do not allow the product to dry onto the surface, or it will be harder to rinse off.
  4. Rinse well with clean water from top to bottom using the 25 – 40-degree nozzle tips. If using the 25-degree tip, be sure to maintain proper distance from the stucco to avoid damage.


Follow the Before Cleaning information above.

  1. In a bucket or large container, mix 1.5 cups Simple Green Oxy Solve House and Siding Cleaner in a gallon of water.
  2. Hose down the siding.
  3. Use a soft-bristle brush to apply the cleaning mixture in sections, scrubbing firmly enough to clean without damaging the siding surface. Don't allow to dry between sections or it will be harder to rinse off.
  4. Rinse with a hose from top to bottom.

[Note: Simple Green Oxy Solve Total Outdoor Cleaner is the ideal direct-release formula for this job, but if you cannot obtain it, Simple Green All-Purpose Cleaner is safe for your pressure washer and works great, too.]

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