All About Roof Flashing Materials
LESLIE: Listening in on WABC we’ve got Karen from Teaneck, New Jersey. How can we help you here at the Money Pit?
KAREN: Well, I am curious about something. We just had a roof replaced and I was wondering, they took off at least 30 feet of copper. What did they use in place of copper? I couldn’t get a definitive answer from the contractor.
TOM: So this is the copper flashing around the chimney and places like that?
KAREN: Yeah, but there were two huge sections.
TOM: Well probably that would have been either around the chimneys or other protrusions and in those cases there are other materials that could be used. For example, there’s a roofing material that’s called Roof Detail Membrane that’s made by Grace that’s like a high-tech synthetic flashing material. The other place that they would probably not use copper any longer would be in the valleys. These are the intersections between two different planes of the roof.
LESLIE: Do you have a lot of those, Karen? Intersecting places on the roof.
KAREN: We have a few, yes.
TOM: That’s probably where most of this came out of. And there are different ways to do valleys. You can do valleys with metal flashing. Or you can do valleys where you weave the shingles; sort of overlap them from side to side.
LESLIE: Is one better than the other?
TOM: Yeah, actually the weave is probably going to be more durable.
LESLIE: Oh, really?
TOM: Yeah, than the – because you have more material there. The flashing can last a long time. I mean the copper flashing can last a long time. But I find very often that there are critical mistakes made because, first of all, most of the roofers are not using copper anymore for whatever reason. Those that are sometimes make errors. Like for example, they’ll put in too long of a piece. When you put metal flashing in a valley you have to be very careful to only attach it on one side and you can only use pieces that are like maybe no longer than eight to ten feet and have them overlap. And the reason for that is because there’s a lot of expansion and contraction and it actually sort of bends the metal as you keep expanding, contracting and expanding and contracting and you’ll actually put like sort of a stress crack in the – yeah, it opens right up.
So, I think the weave is probably just fine and that’s most likely that plus the fact that they may have used like a synthetic roofing flashing material around the protrusions.
LESLIE: Tom, do you think it’s important that Karen sort of pursue this with the roofing installer to find out what was used or just sort of let it go?
TOM: Well, I certainly think that you deserve to know and it should not be (chuckling) that difficult of a question to answer as I just speculated on what might be the answers. But you know, ask them where the flashing came out of and what it was replaced with and this way you know. But those are probably the areas.