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

- Been there, honestly. Flat roofs are tricky - water finds the weirdest paths.
-

“Would you start ripping up layers or call in a pro with infrared?”

Man, I get where you’re coming from. Flat roofs are like a puzzle with half the pieces missing - just when you think you’ve found the leak, water shows up somewhere totally random. I’ve been through this dance a couple times and honestly, it’s enough to make you want to pull your hair out.

I know people swear by infrared, but I’ve always been a little skeptical about the cost. Like, yeah, it’s high-tech and all, but sometimes I wonder if it’s just another way for roofers to pad the bill. That said, I had a buddy who did it and he found a leak that was nowhere near where the water was coming in, so maybe there’s something to it. If you can swing it financially, it might save you from tearing up half your roof for nothing.

Personally, I’m all about trying the cheap fixes first - especially if you’re not seeing obvious damage at the seams or flashings. I’ve gone up there with a flashlight and a tube of roof cement, just looking for anything that looks even a little suspicious. Sometimes it’s just a tiny blister or a spot where the gravel’s thin. Not saying it always works, but I’ve patched a few leaks that way and bought myself another year or two before having to do anything drastic.

Ripping up layers is my absolute last move. Once you start, it’s like opening Pandora’s box - suddenly you’ve got a bigger mess than you started with, and the costs just snowball. Unless you’re seeing major water damage or soft spots, I’d hold off.

Don’t beat yourself up over it. Flat roofs are notorious for this kind of thing. You’re not missing something obvious - sometimes it’s just a matter of trial and error, and a little luck. Hang in there.

Flat roofs really are their own special brand of headache. I’ve spent more time up there with a bucket and a caulk gun than I care to admit. Funny thing is, sometimes the water finds a path that makes zero sense - like, it’ll show up in the middle of the living room but the actual leak is way over by the HVAC unit. I’m with you on not tearing things up unless you absolutely have to... once you start, it’s like opening a can of worms. I’ve had some luck with elastomeric coatings for minor leaks, just as a stopgap. Not perfect, but it buys time.

That’s a good point about water traveling in weird ways - sometimes it feels like it’s got a mind of its own. I’ve seen leaks show up halfway across the ceiling from where you’d expect, especially with older built-up roofs. Elastomeric coatings can help for small stuff, but if it’s persistent, I’d be worried about moisture trapped under the layers. I’ve heard some folks use a garden hose to simulate rain and watch for drips inside, but that only works if you have someone to help and the leak isn’t super sneaky.

Infrared scanning seems like overkill for a small patch, but if you’ve already tried the basics and nothing’s obvious, it might save you from tearing up the whole thing. I’m always a bit wary of just slapping on more patch or sealant without knowing exactly where the water’s getting in - sometimes that just hides the problem until it gets worse. Curious if anyone’s had luck with moisture meters or other gadgets before calling in the pros.

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.

Flat roofs really are sneaky like that... Sometimes I wonder if it’s easier to just move.

Honestly, I get the temptation. Flat roofs are notorious for hiding leaks - water can travel a good distance before showing up somewhere totally unrelated. I’ve seen cases where the entry point was 15 feet away from the stain inside. Thermal cameras are hit or miss, especially if you’re not catching active moisture. Sometimes, it’s just a matter of crawling around up there with a flashlight and a lot of patience. Not glamorous, but sometimes that’s what it takes. Moving feels dramatic... but after enough mystery leaks, I can’t blame you for thinking about it.

Yeah, flat roofs are a pain for this. I’ve chased leaks that seemed to defy physics - water just shows up wherever it wants. One thing that helped me was checking all the seams and flashing, especially around vents and skylights. Sometimes it’s not even the roof itself, but clogged drains or gutters backing things up. I tried the hose test once (one person outside with a hose, one inside looking for drips), and it actually narrowed it down for me. Not perfect, but better than guessing.

Flat roofs are like that one friend who always finds a way to make things complicated. I spent a whole weekend crawling around mine with a flashlight and a bucket of roof cement, convinced I’d found the culprit... only for the leak to pop up on the other side of the room next rain. Turns out, my “fix” just redirected the water. Ended up clearing out a bird’s nest from the drain and that helped more than anything else. Sometimes it’s not even about the roof itself - just all the weird stuff that collects up there.

Totally get where you’re coming from. Flat roofs are notorious for being tricky. A few things that worked for me:

-

“Sometimes it’s not even about the roof itself - just all the weird stuff that collects up there.”

Honestly, sometimes it feels like I spend more time babysitting the roof than enjoying the house... but at least it keeps things interesting.

Had a customer once who swore his roof was haunted - every time it rained, water showed up in a new spot. Turned out, squirrels had chewed a hole right behind the vent pipe flashing. Sometimes it’s not even the roof, it’s the wildlife with a grudge...

That’s wild - never thought about squirrels being the culprit. I’ve been chasing a leak in my own flat roof for weeks now, and honestly, it’s driving me nuts. I keep patching spots but water just finds a new way in. Starting to wonder if it’s coming from somewhere weird, like a vent or even the walls. Anyone else ever have water sneak in sideways? Roofs are trickier than I expected…

Yeah, flat roofs are like the Houdinis of water leaks - just when you think you’ve sealed one spot, water pops up somewhere totally random. I once found a leak coming in through a light fixture, nowhere near the patch I’d just fixed. Turns out, water can travel sideways along beams or even insulation before it finally shows up. I started joking my roof was playing hide and seek with me… and winning. Sometimes it’s not even the roof, but those sneaky vents or flashing. Makes me wish I’d just planted a garden up there and called it a day.

I started joking my roof was playing hide and seek with me… and winning.

- Had a similar situation last winter - leak showed up in a hallway, nowhere near the original patch.
- Traced it back to a poorly sealed vent pipe, not the membrane itself.
- Learned the hard way: water loves to travel along joists and electrical runs.
- Now I always check flashing, seams, and any rooftop equipment first, not just the obvious spots.
- Sometimes it’s not even a “roof” problem but condensation or HVAC lines sweating. Flat roofs really keep you guessing...

water loves to travel along joists and electrical runs

That's spot on. In my experience, leaks almost never show up where the actual breach is - especially with flat roofs. I’ve seen water enter at a cracked skylight curb and end up dripping out of a light fixture two rooms away. Infrared scans can help, but even then, tracing the path isn’t foolproof. Sometimes it’s not a roof issue at all - had one job where attic condensation mimicked a leak for months. Flat roofs are tricky, no doubt about it.

Sometimes it’s not a roof issue at all - had one job where attic condensation mimicked a leak for months.

That’s what worries me. I keep thinking it’s the roof, but part of me wonders if it’s something else entirely. My place is only a few years old, but the flat roof has leaked twice now - once above the bathroom, then again in the living room. Both times, water showed up nowhere near any obvious seams or vents. I had a roofer out and he did a patch job, but the next big rain, same problem.

I’m honestly skeptical about how much those infrared scans help. The guy I hired used one and still couldn’t pinpoint anything. Maybe it’s condensation like you said, or maybe water’s just finding some weird path through the insulation or along the joists. Either way, it’s frustrating.

If I can’t get a straight answer soon, I’m tempted to just open up the ceiling and see what’s going on up there myself... Not ideal, but at this point, I’m running out of patience (and money). Anyone else ever just cut into the drywall to track a leak?