Roof cleaning in Miami, without the pressure

What causes black streaks on Miami roofs

The dark streaks running down tile and shingle roofs are a cyanobacteria called Gloeocapsa magma. It spreads by wind and grows wherever a roof stays warm and damp, which in Miami-Dade is most roofs. Left alone, it’s followed by moss and lichen, which hold moisture against the roof surface. On shingles, the algae feeds on the limestone filler in the shingle. On concrete and clay tile, it gets into the pores of the tile.

The streaks are not only cosmetic. A dark roof absorbs more heat, and heavy growth can keep tiles damp long enough to speed up wear on the underlayment beneath.

Why pressure is the wrong tool

Barrel tile and flat concrete tile crack under foot traffic and high pressure. Shingles lose granules, which shortens their life, and pressure can drive water up and under the tiles into the underlayment. Many roofing manufacturers and industry groups recommend low-pressure chemical cleaning instead. That’s the method KLASH uses on every roof.

What’s included

• A pre-inspection with photos of any cracked, slipped or missing tiles, so nothing is blamed on the cleaning
• Soaking and covering landscaping below the drip line
• Application of the cleaning solution from the eave upward
• Dwell time while the growth breaks down
• A gentle, low-pressure rinse
• Flushing of gutters and downspouts
• Before and after photos

Roof types KLASH cleans

• Barrel (S) tile, clay and concrete
• Flat concrete tile
• Asphalt shingle
• Metal, including standing seam
• Flat and low-slope roofs, including the modified bitumen and coated roofs common on additions and commercial buildings

How long it lasts and how to keep it clean

In Miami-Dade, a properly treated roof typically stays clean for three to five years. Trimming branches back so the roof gets more sun helps it stay clean longer. Some homeowners book a light maintenance treatment every couple of years instead of waiting for heavy staining.

Booking with a house wash

The runoff from a roof cleaning lands on walls, driveways and walkways, so many homeowners book a house wash on the same day. For condo and townhome communities, roofs are often cleaned building by building as part of a larger HOA program.