What would you do if your flat roof kept leaking but you couldn’t find the source?

That’s been my experience too - water seems to find the weirdest paths, especially on older flat roofs. I’ve tried the garden hose trick (with my son running around inside yelling when he saw drips), but honestly, it didn’t always pinpoint the spot. Sometimes the leak would show up nowhere near where we sprayed. I get what you mean about elastomeric coatings. I used one a couple years back and it helped for a season, but the next winter the leak was back, and worse. I’m always skeptical about just adding more goop without knowing what’s really going on underneath.

I did borrow a moisture meter from a neighbor once, but it was kind of hit or miss - seemed more useful for checking drywall than the roof itself. Never tried infrared, though I’ve heard it can spot hidden moisture if you catch it at the right time of day. But for a small patch, it does seem like a lot of trouble (and expense). Has anyone actually found a leak with one of those? Or is it just a fancy way to get told you need a new roof anyway? Sometimes I wonder if we’re just chasing our tails with these gadgets when the real fix is pulling up a section and seeing what’s going on.

Yeah, I totally get the frustration. Water just does its own thing on flat roofs - mine’s been a headache for years. I tried the infrared camera route once (borrowed from a buddy who’s a contractor), and honestly, it was cool to see the images but didn’t really solve anything. The leak was still a mystery. Sometimes I think all these gadgets are just ways to delay the inevitable... At some point, I had to bite the bullet and peel back a section. Not fun, but at least then I knew what I was dealing with. You’re not alone in feeling like you’re chasing your tail - flat roofs are just tricky that way.

Sometimes I think all these gadgets are just ways to delay the inevitable...

That made me laugh because I totally fell for the gadget trap too. I bought one of those moisture meters off Amazon, thinking I’d be some kind of roof detective. All it did was beep at random spots and make me more paranoid. Ended up with a soggy ceiling anyway. In the end, I had to pull up a chunk of the roof myself - felt like I was defusing a bomb. Flat roofs really do have a mind of their own. At least now I know where NOT to put my new couch...

All it did was beep at random spots and make me more paranoid.

I’ve seen those meters cause more confusion than clarity, honestly. Sometimes the readings are just as much about humidity in the air as actual leaks. I’ve had better luck with a good old-fashioned water test - hose on the roof, one person inside looking for drips. Curious if anyone’s tried thermal imaging? I’ve heard mixed things, but never used it myself. Flat roofs are notorious for hiding problems in layers...

Thermal imaging is tempting, but I tried borrowing a buddy’s camera and all it picked up was my neighbor’s cat napping on the warm patch. Not super helpful, unless you’re tracking elusive felines. The hose test worked for me once, but sometimes water finds the weirdest paths - mine ended up dripping out of a light fixture nowhere near the “leak.” Flat roofs really are sneaky like that... Sometimes I wonder if it’s easier to just move.