Yeah, water always finds a way in, doesn’t it? I’ve had better luck since I started priming the deck before peel-and-stick—seems to help it grab, especially in our humid summers. Still gotta check seams every spring though... nothing’s bulletproof.
Priming definitely helps, especially if you’re dealing with older plywood or OSB that’s seen a few seasons. I’ve found that if there’s even a hint of dust or leftover debris, the peel-and-stick just doesn’t bond right—seen too many jobs where it starts to bubble up after a wet winter. Around here (coastal, lots of wind-driven rain), I always run a roller over the deck after sweeping, then hit any questionable spots with a brush-on primer. It’s an extra step but saves headaches down the line.
One thing I do a bit differently: I’ll stagger the seams on the underlayment if possible, just so water has less of a straight shot if something does get through. Not perfect, but it’s helped on some storm repairs. And yeah, nothing’s truly waterproof—every spring I’m up there checking for lifted edges or nails backing out. Had one year where a single missed seam led to a ceiling stain... still bugs me thinking about it.
I get the logic behind priming, especially with older wood, but I’ve actually had mixed results with brush-on primers. Maybe it’s just the brands I’ve tried, but sometimes it seemed to make the surface almost too slick for the peel-and-stick to really grab. Ever run into that? I’ve started using a vacuum instead of just sweeping—seems to get more of the fine dust out of the grooves. As for seams, I’ve always butted them tight and taped over, but never tried staggering. Does that mess with shingle layout at all, or am I overthinking it?
Funny you mention the slickness—had a job last fall where the primer actually made the deck feel almost like plastic. Ended up having to lightly scuff it just so the membrane would stick. As for staggering seams, I’ve seen some folks swear by it for strength, but I’m not convinced it really throws off shingle layout much unless you’re way off pattern. Ever notice any difference in leak spots when you stagger versus line up?
As for staggering seams, I’ve seen some folks swear by it for strength, but I’m not convinced it really throws off shingle layout much unless you’re way off pattern.
I’ve always staggered seams just out of habit, but honestly, I can’t say I’ve ever noticed a big difference in leak spots either way. Most of the leaks I’ve had to chase down ended up being from flashing issues or nail pops, not really the seam layout itself. Maybe if you’ve got a really old deck with a lot of movement, it could matter more, but on newer builds it feels like overkill.
That slick primer thing is real though—had a similar situation with a peel-and-stick underlayment that just wouldn’t grab until I roughed up the OSB a bit. Made me wonder if certain primers or brands are just too “glossy” for their own good.
Curious if anyone’s tried skipping primer altogether and just going straight to membrane? Or is that asking for trouble down the line?