- Had a similar debate here (Central Illinois). Torn between regular felt and synthetic when we did our re-roof after a windstorm trashed the old shingles.
- Ended up going synthetic, mostly because the installer gave a bundle discount, but honestly, I’m not convinced it’s made a huge difference.
- Moisture in the attic usually points to ventilation, like you said. I swapped out my old box vents for ridge vent + soffit combo, and that seemed to help a lot with condensation in the spring.
- Neighbor across the street stuck with felt and his roof’s still bone dry after 12 years, so yeah, install seems to matter more than the underlayment material—at least in our climate.
- One thing I did notice: synthetic was a little easier for the crew to work with, especially on steeper pitches. Less tearing, and it held up better when they had to pause for rain. Not sure that’s a dealbreaker for a basic ranch, though.
- Midwest hail is brutal, but I’m starting to think the shingle quality + how well the flashing is done makes more of a difference than what’s underneath.
Curious—did you check if your attic insulation is blocking the soffit vents? I found a couple spots where mine had shifted and was choking off airflow. Made a bigger difference than I expected.
You nailed it—ventilation is the real game changer, not just the underlayment. I’ve seen so many folks blame leaks or moisture on the felt or synthetic, but nine times out of ten, it’s blocked soffit vents or poor airflow causing the trouble. I always check for insulation drift during inspections... you’d be surprised how often it’s jammed up against the vents. As for synthetic vs. felt, I agree—ease of install is nice, but if the flashing and shingle work isn’t solid, it won’t matter what’s underneath. Midwest hail will find any weak spot, no matter what you use.
My attic’s a mess for airflow—figured I was being thorough with insulation, but turns out I packed it in too tight near the eaves and blocked half the vents. Learned the hard way after a couple ice dams last winter. Honestly, I used to think underlayment made the difference too, but after seeing a neighbor’s brand new synthetic job still get water in after a big storm, I’m convinced it’s all about the details—flashing, ventilation, and how everything fits together.
One thing I’m still not totally sure about: how much does roof pitch factor into all this? Mine’s pretty low-slope, which seems to make ventilation even trickier. Anyone else dealing with low-pitch roofs in hail or heavy snow areas? Wondering if there’s a setup that actually holds up better long-term or if it just comes down to constant maintenance.
Pitch definitely matters, especially with low-slope roofs. You’re right—ventilation gets a lot trickier, and water just doesn’t shed as fast, so any little mistake with flashing or seams can turn into a leak. I’ve seen a lot more issues with ice dams and ponding on these roofs, especially up north. Some folks go with a membrane like EPDM or TPO for low slopes, but even then, it’s all about the install details and keeping up with maintenance. Regular shingle roofs just don’t cut it on anything below a 3/12 pitch, in my experience.
Completely agree—once you drop below 3/12, shingles just aren’t worth the risk. I’ve seen EPDM hold up well in heavy storms, but only when seams are heat-welded and edges are flashed right. Even then, snow load and freeze/thaw cycles can sneak up on you... Maintenance is everything.
