We take care of a variety of roofs in Portland, and each style and material has unique maintenance needs. A three-tab roof is one that will definitely require care before the ten-year mark. If you wait longer than that, you might be out of luck.
Three-tab roofs are made up of a single layer of shingle. Each shingle has little grooves cut into to give it the three-tab appearance. Modern shingles are made up of two layers and it makes the much stronger. The downside to a three-tab roof is that once they’re over ten years old, you have to leave them alone.
If you try to clean them past the ten-year point, you weaken the tabs and can actually break the weather seal that holds them down. Once that seal is broken, a big windstorm will start taking them off.
I had a client with a three-tab about three years ago. He had some light moss, so I prescribed cleaning the moss off, putting a treatment on it, and moving his roof along for many more years. He chose not to do anything.
Fast-forward three years. He calls me back this week and asks me to look at his roof. His moss went from a stage two to a stage ten. The moss is thick. It’s now grown up underneath the tabs, and the moss has broken the weather seal. The shingles are starting to lift up.
We could’ve saved the roof three years ago and kept it going for a few more years. But now he has to leave it alone. If we try to clean it off, the windstorms will begin to do major damage. He’s got to just embrace the moss and start budgeting for a new roof.
Three-tab is an older style of roof and you’re going to have a short window of time to deal with issues. Don’t wait three years. Take care of the problems right away.