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Algae Treatment

Professional pressure washing to remove algae from exterior surfaces like roofs, siding, and driveways.

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Algae and mildew growth on roofs, decks, and siding is common in Johns Creek’s shaded, humid climate. High-pressure washing with targeted cleaning solutions removes unsightly stains safely, preserving surfaces while protecting landscaping and exterior fixtures from chemical runoff or overspray damage.

Proper technique prevents streaking, water intrusion, or material degradation during the process.

We also handle Rust Removal and Oil Stain Removal for Johns Creek properties.

When algae treatment is needed

Algae and mildew thrive in damp, shaded areas, often appearing as green or black streaks on siding, roofs, or decks. Unlike dirt, these growths spread steadily once established, making early treatment more effective.

Check for chalky residue when running a hand over the surface—a sign of oxidation or grime—or compare covered patches (like under a house number) to exposed areas for a clear contrast.

Grime and debris tend to accumulate first in corners, under eaves, and around light fixtures. If cobwebs, dirt, or insect debris are noticeable in these spots, it’s a sign the rest of the exterior may need attention soon.

North-facing walls or sections with overhanging vegetation also show buildup faster due to consistent moisture.

Signs Algae Treatment Is Needed

Green or black streaks on siding, especially on shaded or north-facing walls.
Chalky residue when touching the surface (indicates oxidation or grime buildup).
Visible algae growth spreading steadily instead of staying localized.
Debris collecting in corners, under eaves, or around light fixtures before other surfaces show dirt.

How your home’s layout affects cleaning

Vegetation touching or growing close to siding keeps that section damp longer, speeding up algae regrowth. Trimming back plants to create a gap against the wall helps slow buildup in those spots.

Similarly, a sprinkler head aimed at the siding—rather than the lawn—keeps one section wet daily, making it a hotspot for algae.

Clogged gutters can overflow, sending water and roof grime straight down the siding below. Keeping gutters clear reduces this constant moisture source. Permanently shaded areas, like those facing north or under large trees, will always require more frequent attention, as sunlight exposure directly impacts how quickly surfaces stay clean.

Factor	Impact on Algae Growth	Solution
Overhanging vegetation	Keeps siding damp, speeds regrowth	Trim back to create a 6-inch gap
Sprinkler aimed at siding	Daily moisture exposure	Redirect to lawn or adjust timing
Clogged gutters	Overflow sends grime down siding	Clean gutters seasonally
North-facing walls	Less sunlight, slower drying	More frequent cleaning in shaded areas

Common home layout factors that influence algae buildup and maintenance needs.

What to expect during the process

Before any pressure is applied, landscaping near the foundation is protected with tarps or barriers, and exterior outlets or fixtures are bagged to prevent chemical runoff or overspray.

A cleaning solution formulated for the specific siding material—vinyl, wood, stucco, or fiber cement—is applied first at low pressure to break down algae and mildew chemically.

The siding is then rinsed with low-pressure water (under 500 PSI) in overlapping passes, working top to bottom. Stubborn stains receive a second, more concentrated pass rather than higher pressure, which can force water behind seams and cause hidden damage.

A final clear-water rinse removes residue, and the work is inspected in daylight for missed spots or damage.

Avoiding Damage During Cleaning

Using the wrong pressure setting for the material—such as concrete-level PSI on siding—can crack stucco, split vinyl seams, or strip factory finishes. Always confirm the method (pressure vs. soft wash) and PSI range for each surface before work begins.

How algae treatment works

A thorough algae treatment combines chemical pre-treatment with controlled pressure washing to remove stains without damaging surfaces.

1
Prep and Protection
Landscaping near the foundation is covered, and exterior fixtures are sealed to prevent chemical runoff or overspray damage.
2
Chemical Pre-Treatment
A low-pressure detergent formulated for the siding material is applied to break down algae and mildew before rinsing.
3
Controlled Rinsing
The siding is rinsed with low-pressure water (under 500 PSI) in consistent, overlapping passes to avoid streaking or water intrusion.
4
Spot Treatment and Inspection
Stubborn stains receive a second pass, and the work is inspected in daylight for missed spots or damage before completion.

Frequently asked questions

How do I know if my siding needs algae treatment or just a regular wash?

Algae appears as green or black streaks that spread over time, while dirt or grime may feel chalky when touched. If you notice consistent buildup in shaded areas or under eaves, it’s likely algae. A regular wash won’t address the chemical breakdown needed for stubborn growth.

Will pressure washing damage my siding or roof?

If done correctly with the right PSI for the material, pressure washing removes algae without causing damage. However, using improper pressure—such as concrete-level settings on siding—can crack stucco, split seams, or strip finishes. Always confirm the method and PSI range for each surface.

How often should I treat algae on my home’s exterior?

Frequency depends on shade, moisture exposure, and vegetation near the siding. North-facing walls or areas with overhanging plants may need attention every 1–2 years, while well-ventilated sections can go longer. Regular gutter cleaning and trimming back plants also help extend the time between treatments.

Can I do algae treatment myself, or should I hire a professional?

DIY kits exist, but improper technique—such as inconsistent pressure or wrong detergents—can damage surfaces or leave streaks. Professionals use targeted chemicals and controlled pressure to avoid these issues, especially on delicate materials like vinyl or fiber cement.

Where Johns Creek sits, and what the Census lists nearby

Johns Creek sits in Georgia, and the closest places listed in the U.S. Census Gazetteer are Berkeley Lake (3.7 miles south), Duluth (3.7 miles southeast), Alpharetta (4.7 miles northwest), Peachtree Corners (4.8 miles south).

Within 25 miles of Johns Creek the same source lists 58 distinct incorporated places and census-designated places.

Those figures matter for algae treatment because they are straight-line distances between Census coordinate points: road mileage between Johns Creek and Berkeley Lake runs longer than the 3.7 miles shown, which is why quotes for the same job differ between towns that look close together on a map.

Source: U.S. Census Bureau Gazetteer.

See Roswell, GA for more, or our full range of pressure washing services for our complete lineup.

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Got Questions?

Common Questions About Pressure Washing in Johns Creek

Everything you need to know about pressure washing services in Johns Creek

How much does Algae Treatment typically cost in Johns Creek, GA?

Driveway and walkway cleaning commonly runs around $0.15 to $0.35 per square foot, while a full house wash — siding, typically using a lower-pressure soft-wash method — more often falls in the $200 to $500 range depending on square footage and stories. Roof cleaning, which requires the gentlest method of the three, tends to price separately and higher per square foot than driveway work. A quote that doesn't separate these surfaces by method and price isn't giving a full picture of what's actually being done.

Why does algae and mildew growth on homes in Johns Creek, GA come back so quickly?

Sustained humidity keeps siding, roofing, and shaded concrete damp for longer stretches than drier climates allow, and algae specifically thrives on that lingering moisture combined with organic debris like pollen and leaf litter. A house washed once and left alone in a consistently humid climate can show visible regrowth within months rather than the year or more typical in a drier region. That's the main reason humid-climate homes are often recommended a twice-a-year schedule instead of once.

What are the actual named steps in a professional pressure washing job?

A typical job moves through pre-treatment — applying a cleaning solution to break down dirt, mildew, or algae before any water pressure is used — dwell time, letting that solution sit long enough to work, often 5 to 15 minutes, rinsing at a pressure and nozzle angle matched to the surface, and a post-treatment step for delicate surfaces like sealing a driveway or applying a mildew-inhibiting rinse. Skipping the pre-treatment and dwell steps and going straight to high pressure is a common shortcut that leaves embedded dirt behind.

Can the wrong PSI actually damage a house or driveway?

Yes, and it's one of the more common complaints in this trade. Too much pressure on wood siding or decking can gouge the surface and strip away the protective grain; on asphalt shingle roofing it can dislodge the granules that protect the shingle from UV damage, shortening the roof's life. On concrete, excessive pressure at a tight angle can etch visible stripe patterns, sometimes called zebra striping, into the surface permanently. Matching pressure and nozzle angle to each specific surface is what prevents these outcomes.

What's the actual difference between pressure washing and soft washing?

Pressure washing relies mainly on high water pressure to physically blast dirt off a hard surface like concrete or brick. Soft washing uses a cleaning solution at low pressure, closer to a garden hose than a pressure washer, to chemically break down algae, mold, and mildew on more delicate surfaces like siding, stucco, and roofing, where high pressure risks damage. The two methods are often used together on the same property: soft wash for the exterior and roof, higher pressure for the driveway and walkways.

How often should a home's exterior actually be washed?

Once a year is the most commonly cited baseline for siding and driveways in most climates, timed for spring or early summer before algae and pollen buildup gets heavy. Homes in consistently humid or shaded, tree-covered lots often need attention twice a year since algae and mildew regrow faster in those conditions. Driveways and walkways with heavy tree sap or bird droppings sometimes need spot-cleaning between full washes rather than waiting for the next scheduled visit.

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