Commercial Flat Roof Cleaning Before and After: Green-Gray Growth to Bright White

Flat roofs hold water and grow things. Here is a real rooftop before and after, and what we would want a building owner to look for.

By Paps Exterior Cleaning · September 20, 2026

Before

After

Left: before. Right: after. Photos from a Paps Exterior Cleaning job. The two photos were taken from different spots on the roof.

This is part of our commercial pressure washing in Sarasota & Manatee County.

What the photos show

The before photo looks down a flat roof running alongside a tall wall. The surface is mottled green and gray, with dark patches and staining, and a roof drain with a dome strainer sits in the distance. The shadow of the person taking the photo is in the frame.

The after photo was taken from a different spot, looking along the roof edge. The surface is bright white and even, and the buildings and trees of the city are visible beyond the edge.

Because the two photos are not from the same spot, look at the surface itself rather than the framing: the growth and staining in the first photo are not there in the second.

Why flat roofs get like this

A flat or low-slope roof drains slowly, so it stays damp longer than a steep roof. Damp, sunny and dirty is exactly what algae and mold like. A dark, stained roof also looks neglected from the neighboring buildings, and a bright roof does the opposite.

“David did a soft wash of the building and power washed the sidewalks and curbing at the business I work for. He was professional and thorough. The price was very affordable. Everything is so much brighter and very clean.”Kimberly Bastien, Google review

What building owners can check

• Look at the roof drains. Growth or debris around them is the first sign water is sitting.
• Look along the walls at the roof edge. Staining tends to collect where the roof meets the wall.
• Compare the roof to your neighbors. If yours is noticeably darker, it is carrying growth.

We clean commercial buildings as well as homes, and we specialize in shopping centers and plazas. See our commercial roof and building cleaning, or send us a photo and a quote request.