I get where you’re coming from, but I’ve actually seen radiant barriers make a noticeable difference in attic temps even up north—just depends on how the house is built.
That’s true if ventilation’s bad, but with proper venting, sometimes that extra layer helps more than it hurts. Guess it’s one of those “your mileage may vary” deals.“Otherwise, you’re just trapping heat and moisture together, which can actually make things worse for your roof deck over time.”
The NFVA according to the building plans is higher than the required 300:1 rule, but not quite there when using the 150:1.
I ran into something similar with my tile roof a few years back. The original venting just barely met code, but after a couple of hot summers, I noticed the attic was still holding too much heat. Ended up adding a ridge vent during re-roofing—made a noticeable difference in both attic temps and how hard the AC had to work. If you’re already redoing underlayment, it might be worth considering extra venting now rather than later. Retrofitting after the fact was a pain for me.
Not sure I’d jump straight to adding more venting unless you’re seeing actual issues—like moisture, mold, or crazy high attic temps. Sometimes “more is better” doesn’t really apply, especially if intake/exhaust balance gets thrown off. I’ve seen a few jobs where folks over-vented and ended up with weird drafts or even pulling conditioned air out of the house. If your NFVA is already above the 300:1, you might be fine unless you’ve got a unique situation—like a super low-slope roof or insulation gaps. Just my two cents...
I get where you’re coming from on not just throwing more vents at the problem. I’ve seen that backfire, too.
That’s spot on. Last summer, I was helping out on a reroof where the homeowner had insisted on adding a bunch of extra roof vents because he read online that it would “cool down the attic.” Well, it did—sort of—but it also started sucking air-conditioned air right out of his living room. His electric bill actually went up, and he ended up with weird cold spots in the house.“Sometimes ‘more is better’ doesn’t really apply, especially if intake/exhaust balance gets thrown off.”
I’m not saying don’t add vents if you’ve got real issues like mold or ice dams, but unless you’re seeing those red flags, sometimes it’s just not worth messing with what’s already working. The whole intake vs exhaust thing is trickier than people think. If you throw off that balance, you can end up making things worse—like pulling humid air in from places you don’t want.
One thing I’d check before doing anything is whether your soffit vents are clear and not blocked by insulation or paint. I’ve crawled through more than one attic where the intake was basically useless because someone stuffed insulation right over the vents. No amount of extra roof vents will help if there’s nowhere for air to come in.
If your NFVA is already above code and you’re not seeing obvious problems, I’d be skeptical about adding more unless there’s something unique about your setup (like a super low pitch or cathedral ceilings). Sometimes less is more... or at least “enough” is enough.
Just my two cents from being on jobs where folks tried to outsmart physics and ended up with headaches instead.
“No amount of extra roof vents will help if there’s nowhere for air to come in.”
Couldn’t agree more with that. I’ve lost count of how many times I’ve seen folks add a bunch of box vents or turbines, thinking it’ll solve everything, but the soffits are choked off with insulation or even bird nests. It’s like trying to breathe through a straw with your nose pinched shut. If you’re not seeing mold, ice dams, or crazy heat buildup, sometimes it’s better to just leave well enough alone. Overventilating can actually pull conditioned air out and mess with your energy bills—seen it happen plenty.
