Few things ruin a roof’s integrity more than unsightly moss and algae growth.

Moss thrives in damp, shaded areas, so if you live in the Pacific Northwest, you’ve most likely discovered your roof growing moss at some point.

The Oregon Roof Guys are here to teach you a few techniques on how to prevent your roof from growing moss.

Although moss growth is more of an aesthetic problem in the early stages, it can eventually damage the structure of your roof by uplifting shingles, holding moisture against your roof, staining your roof, forming a slippery and dangerous surface, and promoting the growth of bacteria and mold.


Remove the bulk of the moss by hand scrubbing with a long-handled soft-bristle brush and a garden hose. Spray off your roof with the hose at a downward angle and scrub your roof in a downward motion to avoid lifting any shingles.

Unless you are a skilled professional, it’s best to stay away from the pressure washer as this can remove the shingle granules and cause more damage to your roof.

Chemical washes are also an option to clean your roof. If you decide to use a bleach solution, protect your nearby plants that are vulnerable to the runoff by covering them with tarps or plastic sheeting.


North-facing roofs and shaded roofs are the most susceptible to growing moss. Trim trees and any overhanging branches that are casting excessive shade to help prevent future moss and algae growth that causes unsightly black stains on your roof.

Zinc strips are effective in preventing moss growth on roofs. For best results, install zinc strips at the top of the roof just below the ridge or first row of shingles. Rainfall will wash the zinc down your entire roof, creating a protective coating that will prevent future moss and algae growth.

It’s important to note that zinc strips are not meant to clean your roof, (however after a long period of time they might do so), and you should clean your roof prior to installing the zinc strips.

If you have any questions regarding the maintenance and care of your roof, contact the Oregon Roof Guys! We’ll be happy to answer any of your questions. We specialize in roof repair and replacement in the Eugene and Springfield areas.