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

Curious if anyone’s had luck with roof overlays in really snowy areas? Midwest winters seem to find every weak spot...

I’m in Minnesota and tried a second layer once - regretted it after two winters. Ice dams got worse, and the extra weight made me nervous. Tear-off was pricier but honestly felt safer long-term. Snow just finds its way in if there’s any weakness.

Had a client in Duluth who went the overlay route - looked fine the first winter, but by year two, ice dams were a nightmare. The extra layer trapped more heat, so the snow melted and refroze right at the eaves. Plus, when we finally did a tear-off, there was hidden rot underneath from old leaks that never dried out. I get why folks try to save money with overlays, but in heavy snow country, it’s usually just kicking the can down the road. Sometimes ripping it all off is just less headache in the long run... even if your wallet feels it upfront.

I’ve seen this play out a few times, especially around the Great Lakes. Folks figure a second layer will save them some cash and hassle, but it’s rarely that simple. I inspected a place last February - older bungalow, two layers of shingles, and the attic insulation wasn’t great to begin with. That second layer just made things worse. The snow melted faster, then froze right at the gutters, and you could see the icicles forming by mid-January. When they finally went for a full tear-off, there was black mold on the old decking and even some soft spots where water had been trapped for years.

I get why overlays are tempting - less mess, less labor, and you’re not exposing the house to the elements as long. But in areas with heavy snow or big temperature swings, it’s almost always better to bite the bullet and do a full removal. You get a chance to check the sheathing, fix any hidden issues, and install proper ice and water shield. It’s not cheap, but neither is dealing with rot or mold down the line...

I've run into the same scenario a lot, especially after big wind or hail events. People think a second layer is a quick fix, but in my experience, it just hides problems until they're much worse. Last spring, I was called out to look at a split-level with two layers - first layer was from the late '90s, second was maybe 8 years old. The homeowner started noticing water stains after a heavy storm, but couldn't figure out where it was coming from. Once we pulled everything off, half the decking was spongy and there were clear signs of long-term leaks.

The extra weight is another issue people overlook. Most structures can handle it, but if your roof framing is older or undersized, you’re just asking for trouble - especially with snow load on top of that. Full tear-off isn’t cheap, but you get peace of mind knowing what’s under there and a chance to upgrade ventilation and underlayment. Overlay might make sense in rare cases - like if the first layer is still in great shape and you’re in a mild climate - but up north or anywhere with real weather swings, it’s not worth the gamble.

Had the same debate when I redid my roof last summer. Tried to convince myself a second layer would save money, but once I poked around in the attic and saw some old water spots, I just couldn’t risk it. Curious if anyone’s tried using synthetic underlayment instead of felt? Does it really keep things drier long-term?