Second Layer of Roof Shingles? When to Add vs. When to Remove
LESLIE: Jeff in Pennsylvania is on the line and has a question about the order of things when it comes to a roofing project. What can we do for you?
JEFF: Wanted to check with a neutral third party to see if they have any recommendations or if you’d have any recommendations on putting a heavy, architectural shingle over top of an existing three-tab that’s very thin, very flat.
TOM: Well, first of all, we generally don’t recommend you put a second layer of roofing shingles on it but it comes down to economics. Yeah, we’ll say this: if you put a second layer on, the second layer doesn’t usually last as long as the first layer. Because the first layer holds a lot of heat and that can, over the long haul, wear out the second layer because that heat is the enemy of the asphalt shingle. It forces more oil to evaporate out of it and more of the materials that make it pliable and watertight. And so, second layers generally don’t last as long as the first layers.
The other thing to consider is how long you’re going to be in the house, because you’ll probably have a shortened roof life. If it’s a short-term house for you, maybe you don’t care or you’re trying to save some cash, then maybe you want to go ahead and put a second layer on. But the best way to roof a house is to tear off the old layers and put on a second layer. Weight is not an issue, if that’s what you’re concerned about. Can it handle it? Yeah, it certainly can handle a second layer. But it’s just not good building practice.
JEFF: OK. I thank you much.
TOM: Good luck, Jeff. Thanks so much for calling us at 888-MONEY-PIT.