"Fixing that small spot made more difference than all the insulation upgrades I'd tried before."
I get where you're coming from, but I'd argue insulation upgrades can still be pretty impactful—just not as a standalone fix for leaks. A few years back, I had a similar issue with intermittent leaks around a skylight. After sealing the flashing, I still noticed condensation forming on colder days. Turns out, even after fixing the leak itself, temperature differences and humidity were causing moisture buildup inside.
Upgrading to spray foam insulation in that area actually solved the condensation issue completely. It created a tighter thermal barrier and prevented warm indoor air from hitting the colder surfaces. So while mineral wool alone might not fix moisture issues, pairing proper insulation with leak repairs can sometimes be the key to fully resolving stubborn moisture problems.
Also, totally agree about checking chimneys and valleys—those sneaky little gaps are the worst to track down...
Totally agree that insulation can make a huge difference, but honestly, finding and sealing the actual leak is usually the real game changer. I chased what I thought was condensation for months, upgraded insulation, added venting—did the whole nine yards. But it turned out there was still a tiny crack in the flashing around my vent pipe letting water trickle in just enough to make me question my sanity. Once I finally found and sealed that sucker, the problem vanished overnight.
Still, your point about spray foam insulation is spot-on. After sealing leaks, tightening up insulation definitely helps prevent future moisture issues, especially around tricky spots like skylights or chimneys. Speaking of chimneys...I swear mine was built specifically to torment me with hidden leaks. Whoever designed that flashing must've had a twisted sense of humor.
Had a similar experience with a window leak that drove me nuts for weeks...kept thinking it was old staining from previous owners. Curious, did you notice any clues that finally tipped you off it was fresh water intrusion and not just old damage?
"Curious, did you notice any clues that finally tipped you off it was fresh water intrusion and not just old damage?"
Funny you mention that—I had a similar headache with a ceiling stain that I swore was ancient history. Kept telling myself it was just leftover from the previous owner's DIY disasters. But then one rainy weekend, I noticed the stain had grown slightly darker and felt damp to the touch. That was my "aha" moment. If you're unsure, try marking the edges lightly with a pencil or snapping a quick photo. Check back after the next heavy rain—if it's fresh, you'll usually see subtle changes in size, color, or even texture. Old stains tend to stay pretty consistent, while fresh leaks have a sneaky way of evolving over time. Trust me, water intrusion is annoyingly persistent... better to catch it early before it turns into a bigger headache (and expense).
"Old stains tend to stay pretty consistent, while fresh leaks have a sneaky way of evolving over time."
Usually true, but I've seen old stains "wake up" again if humidity spikes or ventilation changes. Had one spot fool me twice before realizing it wasn't actively leaking—just absorbing moisture from the air.
