Those are sneaky spots for leaks that don’t always show up with the hose test. I’ve seen cases where water travels under the membrane from a puncture way across the roof, then pops up somewhere totally unexpected.
That’s exactly what I’ve run into more than once. The last time I inspected a flat roof with chronic leaks, the owner swore up and down it was coming from a vent pipe, but after pulling back a section of the EPDM, we found the insulation was soaked a good six feet away from where the water was showing up inside. Turns out, a tiny split at a seam near the parapet was channeling water under the membrane. It’s wild how far water will travel before it finds a way in.
I’m with you on the rot and insulation worries. Once moisture gets trapped under there, it’s almost guaranteed you’ll find some mushy decking or even mold if it’s been going on for a while. Sometimes, you don’t see much from the surface, but as soon as you open it up, it’s a different story. I’ve learned to always check the perimeter details and any old repairs—those are usually the weak links, especially on older roofs. Sometimes patching just isn’t worth it anymore...
You nailed it—those hidden splits and old patches are always the first places I look, too. It’s frustrating how water can snake around under the membrane and show up somewhere totally unrelated. Sometimes I wonder if chasing leaks on these old flat roofs is just a losing battle after a certain point... but catching it early definitely saves a lot of headaches down the line. Good call on checking the perimeter—most folks overlook that.
Funny thing, I used to think finding leaks was just a matter of crawling around with a flashlight and some patience... but these old flat roofs really do have a mind of their own. I’ve spent hours tracing stains in the ceiling, only to find the actual leak was halfway across the roof, hiding under a pile of gravel or right at the edge where nobody ever looks.
I get what you’re saying about it feeling like a losing battle sometimes. But honestly, I’m not ready to throw in the towel yet. I’ve seen some pretty rough roofs get a new lease on life with a bit of detective work and some targeted repairs. That said, if you’re patching the same area every year, maybe it’s time to consider whether the whole membrane’s just shot.
One thing I’ve learned the hard way: don’t trust those old patches. They look fine until you poke at them, then suddenly your finger goes straight through. And yeah, perimeter checks are underrated—water loves to sneak in at the edges, especially if there’s any ponding.
At the end of the day, I guess it’s about knowing when to keep fighting and when to call it quits. But I’ll always try one more trick before giving up... stubbornness pays off sometimes.
Flat roofs are notorious for this kind of thing. I’ve lost count of how many times I’ve chased a leak across a roof, thinking I’d found the source, only to realize water had traveled under the membrane from a totally different spot. You’re right about those old patches—sometimes they’re just hiding a bigger problem underneath. I’ve seen roofs where the patch job actually made things worse by trapping moisture.
One thing I always ask folks is: have you checked the drains and scuppers lately? Clogged drains can back up water and force it into places you’d never expect. Also, sometimes it’s not even the roof itself but flashing around HVAC units or skylights that’s the real culprit.
I get the urge to keep patching, but after a certain point, you’re just throwing good money after bad. Curious—have you ever tried a flood test or infrared scan to track down the leak? Sometimes that’s the only way to really see what’s going on under there.
I’ve been dealing with this exact headache since moving in last year. My flat roof is about 18 years old, and after the third “mystery” leak, I started tracking everything step by step. First, I cleared out the drains and scuppers—found a ton of gunk I didn’t expect. Then I checked all the flashing, especially around the skylight, and sure enough, there was a tiny gap I’d missed before. I haven’t tried a flood test yet, but I did borrow an infrared thermometer from a friend to look for cold spots after rain. It actually helped me narrow things down, though it wasn’t perfect. Honestly, patching only got me so far... at some point, I realized I was just delaying a bigger repair.
