Weighing the pros and cons: full roof removal vs. just adding a new layer

We did overlays on a couple of older rentals in the southeast, and ventilation was definitely something I had to keep tabs on. After the second layer, attic temps crept up more than I expected—nothing catastrophic, but enough to notice a difference in summer utility bills. Had to add a couple of extra vents just to balance things out. One place had those old gable vents and that helped, but ridge vents seemed to do better after the overlay.

I’ve heard some folks say the extra weight can be an issue on certain roof frames, though I haven’t run into that personally. Curious if anyone’s seen structural problems pop up from double layers, or if it’s more of a theoretical risk than a real one? For me, as long as leaks and heat buildup are under control, overlays have been worth it for properties I don’t plan to hold forever. But I’d probably think twice on my own house.

That lines up with what I’ve seen, especially on older houses where the framing isn’t exactly beefy. I’ve never had a roof cave in from an overlay, but I do get a little nervous about adding more weight—maybe that’s just me being cautious. Ventilation is a pain, though. My last place had two layers and the attic felt like a sauna until I put in more vents. For rentals or flips, overlays make sense if you’re not planning to stick around long-term. On my own place? I’d probably bite the bullet and do a full tear-off just for peace of mind.

I get the nerves about extra weight, especially if you’ve got those old 2x4 rafters that look like they’re holding on for dear life. I did an overlay once on a rental and yeah, it was quick and cheap, but the attic turned into a sweat lodge in July. For my own place, I went with a full tear-off—messy, but at least I could check for rot and fix some sketchy decking. Peace of mind’s worth a few extra bucks (and a lot of sweat).

- Extra weight’s a real thing, especially with those skinny rafters. Seen too many folks slap a second layer on and then call me after a big windstorm when the decking starts sagging or leaks pop up.
- Overlay is quick, sure, but you’re basically just hiding problems. If there’s rot or old leaks under there, you won’t know till it’s a bigger headache (and a bigger bill).
- Tear-off’s messy—no denying that. But you get to see everything: rot, soft spots, weird old repairs... all the stuff that’ll bite you later if you miss it.
- Heat’s another issue. Two layers trap more heat in the attic. I’ve crawled through attics in July that felt like a sauna thanks to overlays—makes your AC work overtime.
- Cost-wise, overlay saves upfront, but if you need structural fixes or new vents, tear-off pays off long-term. Plus, some warranties require full removal.
- Only time I’d say overlay makes sense? Short-term fix on a shed or rental you don’t plan to keep long.

A little extra mess now usually means fewer surprises down the road. And hey, who doesn’t love finding old wasp nests under the shingles?

Yeah, I’ve seen that extra weight cause some real headaches, especially after a nasty storm rolls through. Folks don’t always realize how much those rafters flex when you double up the shingles. One thing I’d add—if you’re in a spot that gets hail or heavy wind, overlays just don’t hold up the same. I’ve pulled up layers where the bottom one was basically mulch from old leaks nobody caught. It’s tempting to go the quick route, but man, those hidden problems always seem to show up at the worst time... usually right after a big rain.