Cap nails were a game changer for me too—learned that lesson after a big gust sent half my underlayment flapping like a flag. I’ve noticed the “self-sealing” feature isn’t all it’s cracked up to be in colder weather. I’m in Michigan, so spring installs are always hit or miss. And yeah, some brands definitely wrinkle more than others once the sun comes out. The last roll I used got pretty wavy—almost looked like someone left a hair dryer on it all day. Not ideal when you’re trying to keep things smooth before shingles go down.
Can’t say I’ve had much luck with the self-sealing stuff either—last fall, I did my shed roof and figured it’d be fine. Nope. The corners peeled up after a week of cold nights. What worked for me was using cap nails every 12 inches, then going back when it warmed up and pressing down the seams by hand. Not perfect, but at least it stayed put until shingles went on. I’d avoid installing in early spring if you can help it... Michigan weather just doesn’t cooperate.
Not gonna lie, I’ve had a love-hate relationship with self-sealing underlayment too, but I think it gets a bit of a bad rap in cold climates. Michigan’s spring is basically a coin toss—either you’re sweating or scraping frost off your windshield. Still, I’ve managed to get the self-sealing stuff to behave, even on a couple of windy lakefront jobs.
Here’s the trick that’s worked for me (and yeah, it sounds like overkill): roll out the underlayment and let it “relax” for an hour or two if the sun’s out at all. It softens up just enough so those corners don’t curl like potato chips. Then, hit the seams with a heat gun—not enough to melt anything, just enough to warm up the adhesive. It’s a pain, but it beats chasing loose corners in 30 mph gusts.
Cap nails every foot definitely helps, but I’ve found if you’re using a synthetic underlayment (the plastic-y stuff), you can sometimes get away with fewer fasteners if you time it right. The real kicker is making sure you overlap everything by at least 6 inches—most folks skimp here and then wonder why water sneaks in sideways.
One thing I’d push back on: waiting for perfect weather in Michigan is like waiting for a polite seagull. Sometimes you just gotta work with what you’ve got. If you’re stuck doing it early spring, maybe try tarping overnight or stacking some old shingles along the edges until things warm up. Not pretty, but neither is explaining water stains to your spouse.
If you’re still fighting with peeling corners, check the brand too—some of those bargain rolls are about as sticky as a Post-it note in January. The pricier stuff actually seems to grip better when it’s cold, at least in my experience.
Anyway, nothing’s foolproof around here—except maybe duct tape, and even that has its limits after a blizzard...
I hear you on the Michigan weather roulette—one day it’s 70 and sunny, next day you’re shoveling snow off the roof. I’ve been burned by self-sealing underlayment in April more than once. The “relax in the sun” trick is something I wish I’d learned sooner. My first go-round, I laid it out straight from the garage, corners curled up like crazy and I was chasing them around with a staple gun while the wind tried to carry half the roll to Canada.
I’ll second your point about overlap. People (including me, once) get stingy with that and then wonder why there’s water sneaking into the attic. Six inches minimum, sometimes more if I’m feeling paranoid or if it’s one of those weird sideways rain days.
As for brands, I used to cheap out and grab whatever was on sale at Menards, but honestly, that stuff barely stuck when it was cold. Switched to a pricier roll last time—can’t remember the name offhand—and it actually stayed put even when we had frost overnight. Sometimes paying a bit more upfront saves you a headache (and money) down the road.
I do think cap nails are worth every penny, though. Tried skimping on fasteners once and ended up with a section flapping in the wind by morning... lesson learned. Haven’t tried the heat gun trick yet—might give that a shot next time since my hands are usually frozen by noon anyway.
One thing I’ll push back on: synthetic underlayment is great for durability and weight, but I’ve found it can be slippery as heck when there’s dew or frost. Nearly took a tumble last spring, so now I always wear those grippy shoes if I’m up there early.
Anyway, nothing’s perfect in this climate but figuring out what shortcuts aren’t worth it has saved me more than once. And yeah... duct tape only gets you so far before Mother Nature laughs in your face.
Can definitely relate to a lot of this—Michigan weather just doesn’t play fair. I used to be all about saving a few bucks on underlayment, but after dealing with leaks and having to redo sections, I’m with you: the extra cost for higher quality is worth it. Last fall, I tried out a mid-range synthetic (I think it was Grace Tri-Flex or something similar) and it held up even through those early snows. But yeah, it’s slick as ice in the mornings... nearly lost my footing more than once. Grippy shoes are non-negotiable now.
I’ve also learned not to cut corners on overlap or fasteners. Tried using fewer cap nails once and ended up with the wind getting under there—had to climb up and fix it in freezing rain, which I wouldn’t recommend. One thing I do differently is I always check the forecast before starting; if there’s any chance of a cold snap or rain, I wait. It’s not always possible, but rushing has cost me more than waiting ever did.
It’s tempting to go cheap on materials, but factoring in time and hassle, the pricier stuff usually wins out for me.
