Makes me wonder if there are any reliable signs (short of demolition) that hint at hidden rot, or if it’s just a gamble every time.
I’ve wrestled with that same question on a few properties. Sometimes you get lucky and the rot is just around a chimney or a poorly flashed valley, but more often than not, water finds a way to travel. I had one place where the leak started near a vent pipe, but when we pulled up the decking, the rot had crept a good six feet sideways under the shingles. You’d never have guessed it from inside—no stains, no sagging, nothing obvious.
On another project, I thought we’d be able to salvage most of the decking, but once we started pulling up shingles, it was like peeling back an onion—layer after layer of soft spots. Ended up replacing almost all the decking. Sometimes you can tap on the boards from inside the attic and listen for hollow sounds, or look for discoloration, but it’s not foolproof. I’ve seen plenty of “solid” looking wood that crumbled as soon as we put weight on it.
I do think there are subtle clues, though—musty smells in the attic, insulation that’s clumping or looks darker than the rest, or even nails that are rusted out. None of those guarantee rot, but they’re red flags. Still, it feels like a bit of a gamble every time. Curious if anyone’s tried thermal imaging or moisture meters before demo? I’ve heard mixed things about their reliability, especially in older homes where insulation is all over the map.
For what it’s worth, I’ve started budgeting for at least partial decking replacement on any roof over 25 years old, just to be safe. Better to be pleasantly surprised than caught off guard. Has anyone found a method that actually gives you peace of mind before you start tearing things apart?
I get where you’re coming from, but I wouldn’t write off thermal imaging just yet. I’ve seen it catch cold spots from moisture that weren’t obvious any other way, especially in tricky spots like cathedral ceilings. It’s not perfect—older insulation can definitely throw it off—but paired with a moisture meter, it’s helped me avoid a few nasty surprises. Still, nothing beats actually seeing the wood, but I wouldn’t call it a total gamble if you use a few tools together. Sometimes you get lucky and the clues line up.
I’ve had mixed results with thermal imaging too, but I agree—it’s a solid tool when you’re dealing with weird ceiling angles or inaccessible spots. I’d just add, if you’re planning a full roof replacement, it’s worth budgeting for a thorough inspection. Sometimes what looks like a minor cold spot turns out to be a much bigger issue once you open things up. I’ve seen clients get caught off guard by hidden rot, especially in older homes where insulation is all over the place. Layering your tools—thermal, moisture meter, and a good old-fashioned look—really does give you the best shot at catching problems before they snowball.
Totally get what you mean about hidden rot—ran into that myself last year. Thought I was just patching a small leak, but once I pulled up a few shingles, half the decking was mush. Ended up being a way bigger job than I planned. I’m with you on using a mix of tools, but I still trust my gut and a screwdriver for poking around. Sometimes the old-school methods catch stuff the gadgets miss, especially in those weird corners.
Ever notice how you can poke around with a screwdriver and everything seems solid, but then you get one spot where it just sinks right in? Drives me nuts. I get the appeal of all those moisture meters and infrared gadgets, but honestly, I’ve caught more trouble spots just by crawling around and trusting what I see and feel. Maybe it’s just habit at this point.
Curious—when you found that mushy decking, did you end up replacing the whole sheet or just patching the bad sections? I always debate that. Some folks say patching’s fine if you overlap right, others swear by full sheets for peace of mind. I’ve done both, depending on how much time (and patience) I’ve got left by the time I get to that part. But sometimes I wonder if I’m just making more work for myself.
And what about underlayment? I keep hearing mixed things about synthetic vs. felt. Last time, I went with synthetic because it was lighter and supposedly tougher, but it felt slick as ice when I was up there. Not sure if it was worth it. Anyone actually notice a difference in the long run, or is it mostly marketing?
One more thing—how do you guys handle those weird valleys or spots where two roofs meet? That’s where I always seem to find the worst rot, but it’s also the trickiest to fix without making a mess. Flashing never seems to sit quite right for me there. Maybe I’m overthinking it... or maybe there’s a trick I’m missing.
