The green film on your siding is living algae feeding on moisture, humidity, and organic dust, and the only lasting way to remove it is a soft wash that kills it at the root. Scrubbing or pressure blasting removes the surface layer but leaves the organism behind, so it regrows within weeks. A proper soft-wash treatment disinfects the surface and keeps it clean far longer.
Why is green algae growing on my house?
Green algae loves what the Treasure Coast offers in abundance: humidity, warmth, frequent rain, and shade. It shows up worst on:
- North-facing walls that stay shaded and damp.
- Areas under trees or eaves with poor airflow.
- Walls near sprinklers that stay wet daily.
- Textured stucco, which holds moisture in its pores.
It is not a sign of a dirty homeowner; it is simply Florida. Even new homes green up fast in the right conditions.
Is green algae damaging my siding?
Over time, yes. Algae holds moisture against the surface, which can degrade paint, promote mildew and mold, and work into stucco pores where it is harder to remove. On painted block or wood, prolonged dampness leads to premature finish failure. Removing it early with professional house soft washing protects your paint and stucco.
How do professionals remove it?
The reliable method is soft washing:
- Landscaping is wet down and protected.
- A low-pressure cleaning solution is applied to the algae.
- The solution dwells, killing the algae, mold, and mildew.
- A gentle rinse removes the dead growth, leaving the surface clean.
Because high pressure cracks stucco and forces water behind siding, pros use low pressure and let the chemistry work. That is the difference between a wash that lasts a year and one that fails in a month.
If the green comes back within weeks of a cleaning, it was pressure washed, not soft washed. Only killing the algae at the root gives lasting results.
Can I remove green algae myself?
For a small, reachable area, a garden-hose-safe cleaner and a soft brush can help. But for a full house, especially two stories or stucco, DIY risks damage and rarely lasts. The professional-grade solutions that actually kill algae are best applied by a trained, insured crew who can protect your plants and reach high walls safely.
How do I keep algae from coming back?
- Trim vegetation away from walls to improve sun and airflow.
- Redirect sprinklers so they are not soaking the siding daily.
- Schedule an annual soft wash, especially on shaded, north-facing walls.
- Clean gutters so overflow does not streak the walls.
Homeowners across Vero Beach and Fort Pierce find a yearly wash keeps the green from ever taking hold.
Is green algae a health concern?
For most people the algae itself is not dangerous to touch, but the conditions that grow it, damp, shaded, poorly ventilated walls, also grow mold and mildew, which can affect air quality and aggravate allergies, especially near windows and entryways. Slippery green film on adjacent walkways and pool decks is a genuine slip hazard as well. Removing the growth and improving airflow around the house addresses both the appearance and these secondary concerns at the same time.
Why does it come back so fast after a bad cleaning?
If green returned within weeks of a previous cleaning, the surface was almost certainly pressure washed rather than soft washed. High pressure blasts off the visible layer but leaves the living roots embedded in the surface, so the colony simply regrows. A proper soft wash applies an algaecide that kills the organism entirely, then rinses the dead growth away. That is the difference between a clean that fails in a month and one that lasts a year or more, which matters a great deal in our humid climate.
Does the color of the growth matter?
Yes, the shade is a clue to what you are dealing with. Bright green usually indicates algae thriving on a consistently damp, shaded wall. Black streaking often points to a different algae or mildew, common under eaves and on roofs. Reddish or orange staining is typically rust from well-water irrigation, not algae at all, and needs a rust remover instead of an algaecide. A professional identifies the growth on sight and matches the right treatment, which is why guessing with a single store-bought cleaner often disappoints.
Tired of scrubbing green off your walls? Call MainSail Pressure Washing at (772) 559-2666 for a free estimate. Our soft-wash treatment removes algae at the root and keeps your home looking clean far longer.
