Roof Cleaning
Those black streaks running down the north slope of a Florence roof are not dirt and not age. They are algae, and we clean them off with a low-pressure soft wash that kills the growth without touching the shingle granules. Asphalt shingle and metal roofs, single-story ranches and steep two-story homes, across Florence and the Shoals.
A lot of people assume a streaked roof means it is time for a new one. Usually it does not. Once the algae is dead and rinsed away, most roofs come back to the color they were the year they went on, and the shingles underneath are often in better shape than the streaks made them look.
What the black streaks are
The dark stains are a type of algae called Gloeocapsa magma. It shows up on roofs all over the humid South, and the Shoals gives it everything it wants. Florence sits on the Tennessee River with Wilson Lake just upstream, so the air holds moisture most of the year and roofs stay damp long after sunrise, especially the slopes that face north or sit under big trees.
The algae feeds on the limestone filler in many asphalt shingles. It starts as a few dark spots near the ridge or under an overhanging branch, and rain carries it downhill, which is why it forms those long vertical streaks. Left alone, it darkens the whole slope, holds moisture against the shingles and makes the attic run warmer in summer because a black roof soaks up more heat than a grey or tan one.
Moss is the next stage on shady lake lots and wooded streets. Green clumps along the bottom edge or in the valleys hold water like a sponge, and that water works under the shingle edges. Lichen, the crusty grey-green patches, shows up too and grips harder than either one.
Why we never use high pressure on a roof
A pressure washer will take black streaks off a shingle roof. It will also take the granules off with them. Those granules are the gritty top layer that shields the asphalt from sun and weather, and once they are blasted away the shingle ages much faster. High pressure can also lift tabs, break the seal strips that hold shingles down in wind, and drive water up under the laps.
So a roof gets a soft wash. We apply a cleaning mix at low pressure, about what a garden hose puts out, and let it sit on the shingles long enough to kill the algae, moss and lichen down to the roots. Then it is rinsed gently or left for the next rain to finish, depending on the roof and what was growing on it. Heavy moss may need a second treatment and a light hand brushing once it has died and loosened.
It is the same idea we use on vinyl siding and old brick, scaled up for a surface you do not want anyone stomping around on. Most of the work happens from ladders and the roof edge, and we only walk a roof when the pitch is safe and walking it will not cause damage.
Shingle roofs and metal roofs
Most houses around Florence, Sheffield and Muscle Shoals have asphalt shingles, and that is where the black streaks show up worst. The mix and dwell time are set for the shingle, and we watch the runoff the whole way down.
Metal roofs show up more out in the county, on farmhouses, shops and lake places, and on a growing number of newer homes. Metal does not feed algae the way shingles do, but it collects mildew, pollen film and the chalky residue of old paint. It gets a softer mix, a careful rinse and attention to the screws and seams, since a metal roof is slick when wet and painted panels can streak if the mix dries on them in direct sun.
Tile and slate are rare around here. If you have one, send a photo first so we can tell you honestly whether it is a job for us.
Protecting plants and gutters
Anything that runs off a roof lands in the flower beds, so the beds get a lot of attention. Before any mix goes on, we soak every plant below the drip line with plain water so the leaves and soil are already full and cannot soak up the runoff. Delicate shrubs and anything right under a downspout get covered. During the job someone keeps rinsing the beds, and they get one more soak when we finish.
Gutters need to flow, or the runoff spills over the front edge and straight onto the plants. If yours are packed with leaves or pine straw, we clean them out first. Plenty of people pair the roof with clearing the gutters that catch that runoff since we are already on the ladder. Downspouts are pointed away from the foundation and any beds we are worried about.
Cars come out of the driveway, patio furniture gets moved back from the eaves, and pets stay inside until the rinse is done and the ground has had a chance to dry.
How long a clean roof stays clean
That depends on shade, tree cover and which way the slopes face, and honestly we cannot give you an exact figure for any roof. A sunny roof with good airflow stays clean for years. A north slope under oaks on a damp lake lot, like a lot of the wooded lake lots out toward Rogersville, will start to show spots sooner.
Because the soft wash kills the algae at the root instead of just knocking off the surface, regrowth is slower than after a pressure wash. Trimming back branches that hang over the roof helps a lot. So does keeping the gutters clear so the bottom edge of the roof is not sitting in wet leaves.
When the first dark spots come back, a lighter maintenance wash takes care of them before they spread down the whole slope. We work Monday through Saturday, 7am to 6pm, and answer quote requests the same day.
Related
Soft Washing
Low pressure, the right mix and enough dwell time to do the work.
Gutter Cleaning
Gutter cleaning in Florence, AL: leaves, oak tassels and pine straw cleared, downspouts flushed, and black tiger stripes brightened off the gutter faces in the same visit.
House Washing
North-side mildew, spring pollen and red clay splash cleared at the right pressure.
House and Roof Washing in Tuscumbia
We soft wash old paint and brick, clean algae-streaked roofs and do driveways across town.
Questions we get
Is it okay to pressure wash a tile or shingle roof?
Not with high pressure. On shingles it strips the protective granules and can break the seal strips. Tile can crack. Roofs should be soft washed with a cleaning mix at low pressure that kills the growth and rinses away gently.
Will roof cleaning void my shingle warranty?
Shingle makers generally warn against high-pressure washing. A low-pressure soft wash is the method commonly recommended for algae. Check your own warranty paperwork if you are unsure, and we are happy to look at it with you.
Do the streaks mean I need a new roof?
Usually not. The streaks are algae sitting on the surface. Once it is killed and rinsed off, most roofs look close to new. If we see damaged or missing shingles while we are up there, we will tell you.
Can you do the roof and the house the same day?
Yes, and it is the better order: roof first, then gutters, then siding, so nothing from above runs onto a wall that is already clean.
Send us the roof
A photo of the worst slope, taken from the street or the yard, tells us most of what we need: the roof type, the pitch, how heavy the streaks are and whether there is moss. Every job is priced in writing before we start, by the surface and its size, from a photo or a quick walk-around. Roofs over the Tuscumbia side of the river, out in Rogersville or right in town are all on our route. Hit Get FREE Quote Today on the form and the written price comes back to you, with nothing to sign until you are ready.