I always double-check seams now, no matter what the roofer says... learned that the hard way.
Same here—seams are always the weak spot. I had a patch job done on my old EPDM and it looked fine until we got a freeze-thaw cycle, then suddenly water was dripping in my hallway. Turns out the seam lifted just enough to let water sneak in. Modified bitumen’s been more forgiving for me too, especially with our wild temperature swings. Still, I keep a tube of roof cement handy... just in case.
Turns out the seam lifted just enough to let water sneak in.
That’s the thing—seams always seem fine until you get that first real weather test. I’ve noticed even tiny imperfections can cause big headaches, especially with EPDM. Modified bitumen does handle movement better, but I’ve still seen leaks pop up around roof penetrations or flashing. Have you ever tried a flood test to track down a stubborn leak? Sometimes it’s surprising where the water actually finds its way in...
Have you ever tried a flood test to track down a stubborn leak? Sometimes it’s surprising where the water actually finds its way in...
Flood testing can be useful, but it’s not always practical, especially if you’re dealing with an occupied building or older insulation that could get saturated. I’ve seen more than one situation where a flood test ended up causing more damage than it solved—water found its way into wall cavities and made a mess of the interior. If you go that route, just be careful and make sure you’ve got someone monitoring inside.
Honestly, I’ve had better luck with infrared scans, especially after a sunny day followed by a cool evening. The wet spots show up as cooler areas, and it’s a lot less invasive than flooding the roof. That said, nothing beats a good visual inspection after a rainstorm. I usually check all the seams, especially around penetrations and any old repairs. Even a tiny fishmouth or blister can let water in over time.
EPDM seams are notorious for this. The adhesive can look fine but lose grip after a few freeze-thaw cycles. Modified bitumen does handle movement better, like you mentioned, but I’ve still seen leaks at the laps if they weren’t torched or sealed properly. Flashings are another weak point—sometimes the leak isn’t even at the roof level but where the flashing meets the wall or curb.
One trick I picked up: use a garden hose to isolate sections, starting at the lowest point and working your way up. It takes patience, but sometimes that’s the only way to pinpoint a tricky leak without risking more water damage.
At the end of the day, if you’ve patched and patched and still can’t find the source, it might be time to consider whether there’s underlying damage or if it’s worth redoing that section. Sometimes chasing leaks on an old membrane just isn’t cost-effective in the long run.
At the end of the day, if you’ve patched and patched and still can’t find the source, it might be time to consider whether there’s underlying damage or if it’s worth redoing that section.
That’s exactly where I ended up last year. I kept chasing leaks on my old EPDM roof, patching every spot I could find, but water still found a way in. I tried the garden hose trick too—helped a bit, but never nailed it down completely. Eventually, I just bit the bullet and replaced a section. Cost me more upfront, but honestly, it saved me a ton of stress (and buckets) in the long run. Sometimes you just have to weigh how much time and money you’re throwing at it versus starting fresh.
I hear you on the patching treadmill. Sometimes, no matter how many times you go over it, there’s just hidden damage you can’t see—especially with older EPDM. Did you ever check the seams or flashing details? 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. It’s frustrating, but yeah, at a certain point, replacing a section is less hassle than endless detective work. Curious if you noticed any rot or insulation issues once you opened it up? That’s usually my big concern with chronic leaks.
