5 SIGNS YOUR ROOF NEEDS CLEANING
Black streaks don’t fix themselves. Northeast Florida’s humidity, oak pollen, and coastal salt feed an entire biology of algae, mildew, and bacteria on shingle roofs — and by the time the streaks are visible from the curb, the damage has already started. First Coast Property Experts cleans roofs across St. Johns, Duval, and Nassau counties with ARMA-compliant softwash, built on more than a century of combined expertise. Here are the five signs it’s time to call.
1. Black streaks running down the shingles
That dark stain isn’t dirt. It’s gloeocapsa magma, a cyanobacteria that feeds on the limestone filler in modern asphalt shingles. Once the colony is visible, it’s already digging in. Left alone it accelerates shingle aging and eventually forces a premature roof replacement. The Asphalt Roofing Manufacturers Association (ARMA) addresses this directly in their algae discoloration bulletin and recommends low-pressure chemical cleaning (softwash) as the correct treatment.
2. Dark patches or blotches (not streaks)
Streaks run with gravity; patches stay put. Patches are typically a mature algae mat or a small lichen colony anchored into the shingle granules. Patches near chimney flashing or skylight edges often mean moisture has pooled there long enough for the colony to thicken. Ignoring patches lets the biology eat into the granule layer that protects the asphalt from UV, and that’s when the real damage starts.
3. Moss or lichen at the gutter line
Shady north-facing slopes and gutter-line edges are the first places moss and lichen establish in our climate. Moss holds moisture against the shingle 24/7; lichen sends rhizoids into the granule layer. Both are aggressive. If you see green at the gutter line, the colony has likely been growing for 6–12 months already. NRCA maintenance guidance flags moss and lichen as top-tier roof-health threats in humid Southeast climates.
4. Curled or lifted shingles at the ridge
Curling isn’t caused by cleaning — it’s caused by not cleaning. When algae and moss trap moisture against the shingle back, the asphalt dries unevenly through heat cycles. Over a few summers the edges curl up. Shingle manufacturers including GAF and CertainTeed note that keeping the roof biologically clean is one of the most effective ways to hit the full warranty life.
5. Musty smell at the attic vent
If the attic smells earthy or musty after a humid spell, biological growth on the roof may be working its way under the shingles at vent penetrations. That’s a red-alarm sign — it’s the point at which a clean-and-treat visit can still save the roof, while waiting another year likely doesn’t.
What FCPE does about it
Our roof softwash uses ARMA-compliant sodium hypochlorite-based chemistry at low pressure (100–300 PSI). It kills the organism at the cellular level, rinses cleanly, and protects landscaping underneath with tarping and post-rinse. Results are immediate and hold 18–30 months in Northeast Florida’s climate. Paired with our annual exterior plan the roof is rechecked on a predictable cadence.
Request a free roof-cleaning estimate. Related reads: roof cleaning service, algae streaks guide, ARMA roof cleaning (blog).
Roof Cleaning FAQ
Is it safe to clean my roof myself?
Walking on a wet or algae-slicked roof is a falling hazard. We do not recommend DIY roof cleaning even on a single-story home.
Will cleaning the roof void my shingle warranty?
Softwash cleaning is warranty-compliant per ARMA guidance. Pressure washing a roof does void most warranties.
How long does it take to clean an average roof?
Most Northeast Florida homes are 2–4 hours on-site for a softwash, including tarping and post-rinse.
When is the best time of year to clean a roof in FL?
Spring (March–May) and fall (October–November) give the best cure conditions. Summer works but we schedule early mornings.
Do I need to be home during the service?
No. We just need yard access and working outside hose bibs.