I get the concern about recyclability, but honestly, I think the bigger headache is just the weight and mess of having two layers. When we looked into solar, the installer flat-out refused to touch our neighbor’s double-layer roof—said it was too much hassle to guarantee anchoring. Recycling’s tricky either way, but those extra layers just make everything harder down the line. If you’re even half-thinking about solar or a green roof, I’d lean toward full tear-off.
I’ve run into this exact problem a few times on jobs. Double-layer roofs seem like a shortcut up front, but man, they’re a pain later. Last winter, we had to patch a leak on an old house with two layers—finding the source was nearly impossible, and every fastener was a guessing game. Plus, those extra shingles just add weight and can mess with warranties. I get why folks want to save money, but if you’re thinking about solar or anything that needs solid anchoring, I’d always recommend tearing off the old stuff first. It just saves headaches down the road.
That’s interesting—does tearing off the old layer always make sense, though? I’ve heard in some areas (like where winters aren’t as harsh) people just add a second layer and don’t have issues. Is it mostly a problem in places with lots of freeze/thaw cycles, or is it just asking for trouble no matter what?
I’ve actually wondered about this too. I’m in a milder climate (Oregon coast), and when we re-roofed, the contractor said it was fine to go over the old layer since there’s rarely snow or ice here. Saved us a bunch, honestly. But if you’re somewhere with lots of freeze/thaw or heavy snow, I’d be nervous about trapping moisture or hiding rot under two layers. Feels like one of those “depends on where you live” things...
That makes a lot of sense to me. I grew up in Minnesota, where winters are brutal and you get that constant freeze/thaw cycle. I remember my folks went the “second layer” route once, mostly to save money, but a few years later we started noticing weird leaks in spring. Turned out moisture had gotten trapped between the layers and there was some rot hiding under there—total headache.
Out here in the PNW, though, it’s such a different story. Like you said, if you don’t have harsh winters or heavy snow sitting on your roof, going over an old layer isn’t nearly as risky. It’s one of those things where the right answer really does come down to climate and what kind of roof you’ve got. Saving money is great, but peace of mind counts for a lot too.
I think you made a smart call listening to your contractor, especially if they know the local conditions. Sometimes “best practice” just means doing what works best for your situation, not following some one-size-fits-all rule.