As a roof consultant, the first thing I look for when I lean my ladder against a roof is the amount of layers it has. If I lift up the first layer and see a piece of plywood instead of another layer, I breathe a sigh of relief. Multiple layers create a difficult environment for roof maintenance and can lead to early roof replacement.
My neighbor recently put a new roof on top of his old one. I watched them install it really fast. It was obvious that many details, like kick-out flashings, were missed or rushed over. It seems like the entirety of the project was abbreviated or cut short.
When I see multiple layers, I automatically think of the all the extra weight the roof is to sustain. I think of the extra heat it will create and encompass. It’s like having a heating blanket on your home.
I inspected a couple roofs just this week that had multiple layers and both of them were growing moss like you wouldn’t believe. The second layer absorbs that heat and creates a breeding ground for growth. It’s also going to lessen the life span of your roof overall.
Fixing a leak is also an arduous task on multiple layers. On a single layer roof, finding the leak is easy, but when it’s sandwiched between two layers, who knows where it is? It could be leaking far to the left, but manifesting right in front of you. You don’t know because it’s traveling between the layers.
It’s just not worth it. Multiple layers may save you some money in the beginning, but it’s going to cost you a lot more in the end.