06/02/2026
How many of you have seen these dark streaks on a roof and assumed it was time for a replacement?
Most people do. But that streaking is not age and it is not damage. It is a living organism called Gloeocapsa Magma, a type of algae that forms when airborne spores land on your shingles and begin to feed on the limestone filler inside them. As it spreads it creates that dark, almost black streaking pattern you see across the surface. It holds moisture against the shingle, accelerates deterioration over time, and makes a roof look far older than it actually is.
Here is why that matters beyond just curb appeal.
For homeowners selling a home, that algae gives buyers immediate leverage. It raises questions about the condition of the roof, it creates doubt, and it hands buyers a reason to negotiate the price down or walk away. First impressions drive decisions and the roof is one of the first things a buyer sees.
For homeowners with insurance, it can be an even bigger problem. A lot of people do not know that insurance underwriters look at something called pride of ownership when assessing a property. If your roof looks neglected, it signals to an underwriter that the home may not be well maintained overall. That can result in reduced coverage, higher premiums, or in some cases a denial of coverage entirely.
The good news is that in most cases this does not require a replacement. It requires the right treatment.
If your roof looks like this, reach out before you make any decisions. We will take an honest look and tell you exactly what your options are.
Syverson Pressure Washing
(507) 990-9251