I’ve pulled up plenty of old roofs in my line of work, and honestly, I haven’t seen a huge difference in deck condition between felt and synthetic—at least not after 10 years or so. What really seems to matter is whether the attic’s vented right. I’ve seen perfectly dry decks under cheap felt, and rotted messes under pricey synthetics, all depending on airflow. The “breathable” claims sound nice, but if the roof can’t vent, moisture’s still gonna get trapped. Just my two cents from what I’ve seen crawling around up there.
That lines up with what I’ve seen so far. Everyone hypes up the latest synthetic underlayments, but if the attic’s a sauna, it really doesn’t matter what’s underneath the shingles. I’ve pulled up old felt that looked rough but the plywood was fine, just because the airflow was decent. On the other hand, I’ve seen some “breathable” synthetics trap moisture just as bad as anything else when vents were blocked. Maybe the material makes a difference in extreme climates, but around here, venting seems to be the real game-changer.
- Had a job last summer where we used the fancy synthetic underlayment, but the attic vents were half blocked by insulation.
- Even with the “breathable” stuff, the plywood started showing dark spots after just a year.
- On another house, we did basic felt but made sure every vent was clear—no issues at all, and it’s been a few years now.
- Guess it’s like you said…venting seems to matter way more than whatever underlayment you pick, at least where I’m working.
- Kinda wild how much airflow changes things.
Guess it’s like you said…venting seems to matter way more than whatever underlayment you pick, at least where I’m working.
Totally agree—venting is underrated. I used the “fancy” underlayment once too, but didn’t clear out the soffit vents enough. Ended up with a musty attic and some warped sheathing. Next time, I just used regular felt and made sure every vent was open. No issues since. Sometimes the old-school way just works better, huh?
Sometimes the old-school way just works better, huh?
Can’t argue with that—sometimes regular felt and proper venting does the trick. I’ve noticed a lot of guys focus on underlayment upgrades, but if your airflow’s blocked, it barely matters what you use. Out here in the Midwest, ice dams are a pain if the attic can’t breathe. Anyone else run into weird moisture stains even when the roof looks fine from outside? Always makes me double-check those vents before anything else...
