You’re spot on about the musty smell being a warning sign, especially if you’re dealing with an older roof system. I’ve seen too many cases where folks just add another layer, thinking it’s a shortcut, but hidden moisture and rot can turn that into a nightmare down the road. Decking rot above a rafter is classic—doesn’t show up until you pull everything off, and by then, you’re already committed.
Weight is something people really underestimate, especially with houses built before modern codes. Two layers of shingles plus snow? That adds up fast, and older rafters just weren’t designed for it. I’ve seen slight dips in the ridge line or sagging over the eaves, and it’s almost always from overloading.
Codes can be all over the place, but even if two layers are technically allowed, I’d argue it’s not always wise. A tear-off is more work, sure, but you get to see what’s really going on under there—and you’re not gambling with your structure. Sometimes peace of mind is worth the extra hassle and cost.
Codes can be all over the place, but even if two layers are technically allowed, I’d argue it’s not always wise.
That’s something I’ve wondered about—how much do local codes actually reflect what’s best for older homes? My place is from the late 60s, and I know the rafters aren’t as beefy as what you’d see now. Has anyone run into trouble with insurance after adding a second layer? I’ve heard some companies get picky if there’s any sign of sag or past water damage. Just curious how that plays out in practice.
Has anyone run into trouble with insurance after adding a second layer? I’ve heard some companies get picky if there’s any sign of sag or past water damage.
Yeah, I’ve seen insurance get weird about that, especially if the roof’s already showing its age. Did you check if your policy says anything about multiple layers? Some are fine with it, others act like it’s a big red flag. Wondering if anyone’s had to rip off a second layer just to keep coverage?
Had a neighbor get dinged by insurance after adding a second layer—adjuster flagged it during a wind claim, said too much weight for the old rafters. They had to tear both off and start fresh or risk losing coverage. Not cheap...
