MARK: I’ve got a house that’s probably about 50 years old and it’s had the roof replaced on it one time. It’s got a tar and a gravel – a lava rock, roof tar. And I know I’m going to have to replace that here one of these days. Now, the decking on the roof is actually my ceiling. It’s 2×6 tongue and groove. And I’m sure they’ve got tar paper on top of that and then some insulation and then the tar and lava rock. And I’m wondering how I’m going to have to replace that and what type of insulation I could use on that. It doesn’t have a lot of pitch.
TOM: And when you say decking, we’re talking about the structural decking. You don’t use this as a recreational deck, is that correct?
MARK: No, uh-uh. No, that’s the – the 2×6 is the actual decking for the roof. Like I said, it’s the ceiling on the inside of my house.
TOM: So you’re looking for options in low-slope roofing. Is that correct?
MARK: Right, yes, uh-huh. I’d like to go back with metal roof but what do I do on top of the decking that I’ve got?
TOM: Right. Well, if you were going to go with metal roof, you are going to probably go down to the original decking and then you’re going to put a new insulating board on top of that. And then you’re going to put the metal roof over that. And you’re pretty much going to do that same assembly regardless of the type of roof you use. If you were to use a traditional flat roof – like a modified bitumen, which is sort of like a rubberized asphalt kind of product – you would do it in the same sort of fashion.
It’s real important, though, that when you choose your roofer, you want to make sure, Mark, that you find one that’s really experienced with flat roofs. Because what I’ve found is that very often you have groups of roofers that are just terrific with pitched roofs but when it comes to the flat roof, it’s only sort of the occasional job. And they don’t always have the skill set to do that.
The guys that do flat roofs a lot are more of the commercial roofers. And you could pretty much go with any technique that they recommend, based on your particular situation, and it’s going to get done well. But I would just say that make sure that – the devil is in the detail with these flat roofs because they’re – if you have any defects in the assembly of the roofing material itself or more commonly, the flashing points where pipes come through the roof and that sort of thing, that’s where the leaks actually show up.
So it’s not an impossible situation. It’s just unusual for residential.
MARK: The original builders here, they put a thin insulation up there and it got so hot in the summer. They took it out and put more insulation in and I don’t know what they’ve done.
TOM: Yeah, there are insulation boards for that. And by the way, about the heat in the summer, if that’s an issue, that’s something that the metal roof can actually help you a lot with. Because the new metal roofs today, they actually have a low-E coating. And they reflect the heat back off of the roof so it doesn’t become this huge heat sink that’s throwing a lot of radiant energy down into your room.
MARK: OK, great. Yeah, I’m hoping to go metal and then forget it.
TOM: I got it. Got it, Mark. Alright, man. Good luck. Thanks so much for calling us at 888-MONEY-PIT.