Can Simple Green Be Used to Clean Stucco? The Ultimate Guide

Hey there! Lillie here, your friendly home improvement expert. If you‘ve got a stucco exterior that‘s seen better days, you‘ve come to the right place. Stucco is notorious for attracting dirt, grime, and those pesky mold and mildew stains. But don‘t worry – with the right products and techniques, you can have your stucco looking fresh and bright again in no time.

In this comprehensive guide, we‘ll cover everything you need to know to clean stucco effectively and safely:

What is Stucco and How Does it Get Dirty?

• What is stucco made of?
• Common stucco cleaning problems
• Causes of stucco dirt and stains

Can You Use Simple Green on Stucco?

• How Simple Green works
• Pros and cons of using Simple Green
• When not to use Simple Green

Step-By-Step Guide to Cleaning Stucco with Simple Green

• Supplies needed
• Mixing the cleaning solution
• Application and scrubbing tips
• Rinsing and drying recommendations

Advanced Stucco Cleaning Solutions

• Cleaning products for specific stains
• Bleach solutions for mold and mildew
• Using pressure washers safely

Preventing Future Stucco Stains

• Gutter maintenance
• Landscaping and plantings
• Regular washing
• Stucco sealing

Let‘s start by looking at what exactly stucco is and how it gets dirty in the first place.

What is Stucco and How Does it Get Dirty?

Stucco refers to a durable finish coating used on building exteriors. It consists of a mixture of:

• Sand – Up to 80% of the mixture, provides bulk and strength
• Portland cement – Binds the mixture and hardens it into a stone-like material
• Lime – Improves workability and flexibility
• Water – Activates the cement while mixing

This wet plaster mix is applied in one or more layers over a wire lath attached to the exterior wall surface. Once dry, stucco‘s uneven, textured appearance is both decorative and protective.

But while stucco is quite durable, it is still porous like concrete or natural stone. This means it easily absorbs dirt, grease, mildew and other gunk from the environment.

According to industry surveys, cleaning exterior surfaces is the #2 source of calls to professional power washing companies, behind only driveway cleaning. And a national poll showed that 68% of homeowners pressure wash their home’s exterior once a year or more.

Let‘s look at some of the most common cleaning challenges you may encounter with a stucco surface:

Dirt and Grime

Plain old dirt, dust, pollution, and grime from the environment collects on stucco over time. This causes once-bright white or colored stucco to become dark and dingy looking.

Horizontal surfaces like ledges accumulate the most dirt buildup because they don‘t get washed by the rain. Areas close to sidewalks and driveways also collect more dirt from foot traffic and vehicle exhaust.

Mold and Mildew Growth

The porous nature of stucco means moisture easily penetrates into the material. In shaded or damp parts of the home, this moisture enables mold, mildew, algae, and other biofilms to grow on the surface, leaving dark blotchy stains.

Mold loves wet, humid climates. A National Institutes of Health study discovered mold spores on more than 50% of exterior building surfaces sampled nationwide.

Green, black, orange, and other discolorations indicate mold infestation on stucco walls. North, east, and shaded walls tend to grow the most mold.

Rust Stains

While traditional stucco uses steel wire lath for support, newer polymer-modified stuccos often use fiberglass mesh instead. However, steel reinforcement bars can still cause rust stains to bleed through stucco layers.

Iron and other metals naturally present in lime, tap water, soil, and even some sands can also oxidize to produce reddish-brown rust stains on stucco.

Coastal areas are especially prone to rust staining due to the corrosive effects of salt air. Rust may first appear as small pinholes, which then spread into larger stained areas if left untreated.

Organic Staining

Leaves, berries, bird droppings, insect secretions, and other organic materials often leave stubborn stains on stucco. Dark streaks down from roofs and windows are telltale signs of organic stains.

Overflowing gutters and wind-blown debris concentrates organic stains in certain areas. Stucco near trees and shrubbery also collects more falling leaves and sap drips leading to staining.

Hard Water Staining

Sprinklers and rain wash mineral-rich hard water over stucco walls. As the water evaporates, minerals like calcium, magnesium, and silica are left behind as white salt deposits or efflorescence.

Hard water stains are usually seen as white chalky patches below areas wetted by sprinkler heads or along the drip line of roof edges. The stains leach into the porous stucco.

Oil and Grease Stains

Stucco walls near driveways, garages, or under kitchen exhaust vents often get oily stains. Automobile leaks and emissions leave behind hydrocarbon grease and tar residues. Food grease particles create dark oily-looking stains.

Overflowing gutters can concentrate dirty roof runoff onto stucco surfaces below, creating dark streaking stains.

Now that you know how stucco gets dirty, let‘s look at how Simple Green can help tackle some of these cleaning challenges.

Can You Use Simple Green on Stucco?

Simple Green is a mild, eco-friendly cleaner that can be highly effective for cleaning stucco surfaces when used properly. Let‘s look at the pros and cons of using it on stucco:

The Pros of Simple Green for Stucco Cleaning

• Non-toxic and biodegradable formula is safer for you and the environment

• Can help clean common stucco problems like dirt, grease, mildew, and organic stains

• Economical concentrate makes many gallons of cleaning solution

• Easy to find at grocery and hardware stores nationwide

Potential Cons of Using Simple Green on Stucco

• May not be strong enough for severely stained or neglected stucco

• Requires scrubbing; does not work instantly like harsher chemicals

• Can leave white residue if rinse water is hard and not thoroughly flushed

• Multiple applications may be needed for thickly soiled areas

Always spot test Simple Green in an inconspicuous place before use to check compatibility with your specific stucco type and color.

Never use Simple Green on painted or sealed stucco, or on indoor stucco surfaces. It should only be used on bare exterior stucco walls.

For best results, use Simple Green House & Siding cleaner or Simple Green Outdoor Cleaner which are specially formulated for buildings. Now let‘s look at how to use it to clean stucco surfaces…

Step-by-Step Guide to Cleaning Stucco with Simple Green

Cleaning stucco with Simple Green is a pretty straightforward process, but proper methods will give you better results. Here are the basic steps:

Supplies You‘ll Need

• Simple Green House & Siding or Outdoor Cleaner concentrate
• Water hose or pressure washer
• Plastic bucket or spray bottle
• Long handled stiff scrub brush
• Optional: garden sprayer or power washer

Mix the Cleaning Solution

Check the product label, but the typical dilution is:

• 2 ounces (1/4 cup) Simple Green concentrate per gallon of warm water for moderate dirt
• Up to 4 ounces (1/2 cup) concentrate per gallon of water for heavier grime

Mix in a bucket first before transferring to a spray bottle if using one. I recommend wearing gloves and eye protection when diluting or handling Simple Green.

Wet Down the Stucco Surface

Use a garden hose to thoroughly pre-wet the entire stucco area you will be cleaning. This helps soften and loosen soil.

Start from the top down so water runs over lower areas. Avoid using high pressure, which can damage soft or deteriorated stucco.

Apply the Simple Green Solution

Apply the diluted Simple Green solution liberally over the wet stucco using a spray bottle, garden sprayer or by directly brushing on. Let it sit for 2-3 minutes.

Reapply the solution as needed to keep the area wet. Simple Green works best when surfaces stay wet and soiled as long as possible. But don‘t let it dry completely.

Scrub, Then Rinse

Vigorously scrub stained or excessively soiled areas using a stiff nylon or other non-metal brush. Wearing gloves can give you a better grip.

Then rinse everything off thoroughly with a regular garden hose using moderate pressure. A power washer on a wide-angle low pressure setting can also help blast off caked-on grime.

Rinsing removes the dissolved dirt so it doesn‘t re-settle into the porous stucco. Check for any Simple Green residue and re-rinse if needed.

Let Fully Dry

It‘s important to allow the stucco to completely dry out before sealing, painting, or applying any other treatment. Sealers and paints won‘t adhere well to damp surfaces.

Drying could take 1-3 days depending on humidity, temperature, and sun exposure. Accelerated drying in a day can usually be achieved using fans, heaters, or dehumidifiers if needed.

Application Tips

• Wear gloves, eye protection, old clothes and shoes to avoid damage

• Do one wall section at a time over several sessions for manageability

• Use an extension pole to reach high areas without a ladder

• Avoid metal brushes or abrasive scrubbers that might scratch stucco

Repeat the Simple Green cleaning process regularly to prevent major buildup of stucco dirt and stains. Yearly or biannual cleaning is recommended for most homes.

That covers the basics of using Simple Green to clean stucco walls. But for really stubborn stains, you may need to use some more advanced cleaners. Let‘s look at those next…

Advanced Stucco Cleaning Solutions

For badly neglected stucco, Simple Green alone may not be enough to fully remove ingrained dirt, mold, rust stains, efflorescence, and other severe staining. Here are some stronger solutions:

Mold and Mildew Removers

To remove heavy mold and mildew growth, use:

• Bleach solution – 1 part bleach to 3 parts water. Apply after pre-wetting, scrub, then rinse thoroughly. Wear protective gear when using bleach.

• Oxalic acid – Found in wood bleach. Use according to package directions and rinse thoroughly. Good for organic stains too.

• Hydrogen peroxide cleaner – Safer alternative to chlorine bleach. Scrub on peroxide solution, wait 5 minutes, then rinse.

NOTE: Always pre-wet stucco before applying cleaners to prevent absorption into the pores. Wear gloves and eye protection when handling caustic chemicals.

Rust Stain Removers

For dealing with stubborn rust stains try:

• Oxalic acid – Available as wood bleach. Follow label directions on dilution and application. Rinse thoroughly. Repeat if needed.

• Phosphoric acid – Sold as concrete etchers. Dilute 10:1, apply with stiff brush, let sit 5 minutes, then rinse. Use proper PPE.

• Citric acid – Mix 1 lb citric acid per 1 gallon water and scrub on. Rinse thoroughly when done. Milder and easier to handle than other acids.

Mineral Deposit Removers

To clean off calcium, lime, and other hard water stain deposits:

• White vinegar – Spray or scrub on undiluted vinegar, wait 5 minutes, then rinse off. Repeat as needed.

• Lemon juice – Natural citric acid. Scrub concentrated juice on deposits, wait 5 minutes, then rinse thoroughly.

• Phosphoric acid – Sold as concrete etchers. Follow label dilution, apply with stiff brush then thoroughly rinse.

Using Pressure Washers on Stucco

Pressure washing can help clean many stucco homes much faster than hand scrubbing. However, the high pressure water can damage soft or deteriorated stucco if not done properly.

Follow these guidelines when pressure washing stucco:

• Use lower pressure tipped wands, ideally under 2000 psi

• Keep nozzle 6-12 inches back from the wall

• Use a wide fan spray tip, not a zero-degree jet which can etch stucco

• Avoid aiming directly at cracks or imperfections in the stucco

• Sweep spray horizontally across the stucco, not up and down

• Be extra cautious around window and door trim edges where stucco is thinner

Hiring a professional pressure washer experienced with stucco is recommended if you are unsure about doing it yourself. They will have the proper equipment and knowledge for your particular stucco finish and situation.

Okay, let‘s wrap things up with some tips on how to keep your stucco walls cleaner going forward…

Preventing Future Stucco Stains

Sure, cleaning stucco is important. But the best defense is preventing stains and buildup in the first place through good maintenance and stucco care. Here are some helpful prevention tips:

Manage Water Runoff

• Install gutters and extend downspouts to route water away from stucco walls

• Repair leaky gutters immediately to prevent streaking stains

• Use drip irrigation for landscaping and low-flow sprinkler heads

• Adjust sprinklers to avoid directly spraying stucco walls

Smart Landscaping

• Prune back trees and shrubs touching the structure

• Plant beds and shrubs away from stucco walls

• Use gravel mulch beds near stucco to reduce mud splashing

Handle Dirt Buildup

• Use doormats, gravel paths, and fencing to limit dirt near stucco

• Remove exterior AC units, debris, and unnecessary items touching stucco

• Consider installing wash pads with drains near entry doors

Regular Washing

• Wash stucco annually with a mild soap and low pressure water

• Pay special attention to horizontal surfaces where gunk accumulates

Stucco Sealing

• Apply a breathable water-repellent sealer to protect the stucco surface

• Look for acrylic, silicone, or fluoropolymer sealers

• Reapply sealer every 3-5 years for maximum effectiveness

• Repair cracks and holes properly before sealing

And there you have it – everything you need to know to keep stucco surfaces clean and looking fresh! The key is regular maintenance cleaning and taking steps to limit dirt and water exposure in the first place.

I hope you found this guide helpful. Let me know if you have any other questions about maintaining your home‘s exterior stucco. I‘m always happy to help out with more tips and advice. Happy cleaning!