Ventilation really does seem to get overlooked a lot, especially by builders just trying to check boxes. When I redid mine, I went with both ridge and soffit vents, figured better airflow couldn't hurt. It made a noticeable difference in summer—attic temps dropped significantly, and the upstairs rooms felt cooler without cranking the AC as much.
About insulation thickness though, I'm not entirely convinced ventilation alone makes insulation less important. Even with great airflow, if your insulation is too thin or unevenly installed, you're still losing heat in winter and gaining it in summer. Ventilation helps manage moisture and attic temps, but proper insulation keeps your home's interior comfortable year-round.
One thing I'm still curious about myself: has anyone tried adding reflective barriers under their roof decking? I've heard mixed things—some swear by them, others say they're gimmicky... Wondering if that might be another layer worth considering along with good ventilation and insulation.
I've installed reflective barriers on a few jobs, and honestly, the results were mixed. On one project, the homeowner swore it made a noticeable difference in attic heat during summer afternoons. But another customer didn't notice much change at all—could've been due to their existing insulation being solid already.
In my experience, reflective barriers do help somewhat if your attic gets direct sunlight exposure and your roof decking heats up significantly. But they're definitely not a substitute for proper ventilation or insulation. I'd say they're more of an extra step you can take once you've already nailed down the basics like soffit/ridge vents and good insulation depth.
Also, about ice barriers—I usually put them along eaves, valleys, and around any penetrations (chimneys, skylights). Those spots are most prone to ice dams and leaks. Better safe than sorry...
"Better safe than sorry..."
Couldn't agree more on the ice barrier placements—especially valleys and skylights. Had a customer once who skipped the valleys (against my advice), and come February, guess who was back on the roof dealing with leaks? Yep, lesson learned the hard way. Reflective barriers are hit or miss for me too, but ice barriers...those things are worth every penny in the right spots.
"Had a customer once who skipped the valleys (against my advice), and come February, guess who was back on the roof dealing with leaks?"
Haha, sounds like me last winter...thought I could save a few bucks skipping the ice barrier in one valley. Big mistake. Ended up spending way more fixing water damage inside. Lesson learned—some things you just don't skimp on, especially when it comes to roofing.
I get what you're saying, but do you think ice barrier is always necessary in every valley? I've worked on a few roofs where the pitch was steep enough that snow and water cleared pretty quickly, and honestly, the barrier seemed kind of redundant there. Maybe it depends more on the roof angle or local climate conditions rather than just defaulting to always putting it in valleys?
Last summer, we did a roof for a guy who insisted on ice barrier everywhere—even spots I thought were totally unnecessary. Definitely felt like overkill at the time (and extra cost), but he was happy with the peace of mind. Still, makes me wonder if there's some middle ground between "always" and "never." Have you guys ever skipped it without issues, or am I just tempting fate here...?
