There are a variety of reasons why you might want to clean your roof. Maybe you have a moss problem, or live under a bunch of trees and want to clean off the debris. Whatever the reason for cleaning the roof, pressure washing is NEVER the way to do it. Let me explain why:
1. It removes granules from the shingles. Shingles are comprised of a bottom layer of fiberglass, a water resistant layer of tar, and a top layer of granules. Granules protect the two other components from the elements, especially damaging sun rays and heat. But even if some of those granules are removed, you will see a dramatic drop in the longevity of your roof. I saw this in a home I inspected just last week.
2. It increases potential for leaks. Just 3 days ago my neighbor was pressure washing his roof. As I write this, he is on his roof inspecting lifted shingles and I’d bet all the money in my pocket that he’s trying to locate a leak. The pressure can push water up the roof and back behind the shingles while you’re pressure washing, or you can damage the tar layer by tearing holes in it.
3. It voids any warranties. A good roofing company will give you a warranty for their installation of your roof. When you call them later because there is a leak, they will send someone out to inspect your roof. The first thing he will look for is if the roof shows signs it has been pressure washed. If it has, you have already voided the warranty, and [whether the leak is related to the pressure washing or not] you’ll be paying for the repairs from the leak.
Bottom line – there are other better, gentler ways to clean your roof without causing damage which will keep your warranty intact. But we’ll have to save that discussion for another day. One of these days we’ll get into how to properly clean your roof.
