Black streaks on Florida pavers are usually mold or mildew, while the green film you see is most often algae or, in shadier spots, moss. Both thrive on the salty, humid air and the constant moisture that Brevard's coastal climate provides.
Coastal breezes carry salt that settles on the paver surface. Over time the salt eats away at the binder in concrete pavers, creating microscopic pores where microbes can cling. UV rays break down the sealant, especially after years of exposure, leaving the stone more porous.
When those pores open, water from a summer rain can sit longer, and the salty residue gives algae a nutrient boost. The result is a patchwork of dark streaks and green patches that spread faster after a hurricane‑season downpour.
Summer downpours dump inches of rain in a single afternoon, then the sun bakes the pavement dry for hours. That wet‑then‑dry rhythm is perfect for mold spores that need moisture to germinate but also need air to grow.
Hurricane season adds another layer. Floodwater can bring organic debris, sand, and even pondweed that settles on pavers. When the water recedes, the leftover nutrients feed the same organisms that cause the black streaks and green film.
Algae are the green layer you see most often. They are simple plants that need light, water, and a bit of nitrogen—often supplied by airborne dust or runoff. Mold appears as black or gray streaks, thriving in shaded corners where water lingers.
Moss prefers shade and constant moisture, so you'll find it under overhangs or near tall palms. In rare cases, a thin oil film from nearby boat traffic can give a slick, dark sheen that looks like mold but is actually petroleum residue.
Regular cleaning removes the organic layer that feeds microbes. A high‑pressure wash—like the pressure washing in Melbourne we do for many homeowners—blasts away algae, mold, and sand without harming the paver.
After cleaning, a quality sealant restores the protective barrier. In our experience, sealing reduces new growth by up to 70 percent when the sealant is reapplied every three to five years, depending on traffic and exposure.
Q: How often should I have my pavers cleaned?
A: In Brevard, most homeowners schedule a professional clean and seal every three to five years. If you notice new black streaks after a heavy rain, a spot clean can keep the problem from spreading.
Q: Does sealing stop algae and mold completely?
A: Sealing creates a barrier that makes it harder for spores to attach, but it doesn't eliminate them forever. Regular cleaning and good drainage are still needed to keep growth at bay.
Q: Can I clean the pavers myself?
A: You can scrub with a garden hose and a mild detergent, but without proper pressure and a sealant, the results are short‑lived. Professional equipment reaches the pores and applies a sealant that lasts longer.
Q: Will hurricane season make the problem worse?
A: Yes. Floodwater often carries extra nutrients and debris that feed algae and mold. After a storm, inspect the pavers and consider a quick wash if you see new growth.
Want a straight answer for your own driveway or patio? Groundworks gives every Brevard homeowner a free written estimate — call or text (321) 586-9227.
— Groundworks Pavers & Turf · licensed & insured · Brevard County, FL