Mixing vent types is one of those things that seems to break all the “rules,” but I’ve seen it help too—especially in older houses with weird attic layouts. One thing I’m curious about: has anyone had issues with wind-driven rain coming through gable vents after making changes? I had a client where that became a problem after we added more soffit openings. Maybe it’s just our coastal climate, but it surprised me.
I’ve actually wondered about this too. Our place is about 70 years old, and when we opened up the soffits for more airflow, I noticed the attic insulation near the gable vents was getting damp after storms. Not a ton of water, but enough to make me nervous. We’re not coastal, but we do get strong winds. I’m not sure if it’s just the added intake or maybe the vent baffles aren’t doing enough to block sideways rain. I’m thinking about adding some kind of rain guard inside the vents, but I haven’t tried it yet. Hasn’t been a disaster, but definitely something to watch.
That’s a pretty common issue with older homes, especially when you start messing with airflow and the original venting setup. I’ve seen similar damp spots in attics after retrofitting soffit vents, and it’s usually a mix of wind-driven rain and not having enough of a physical barrier behind the gable vents. Sometimes the insulation just acts like a sponge if there’s any gap at all.
Have you checked whether your gable vents have any kind of louver or hood on the exterior? Some of those old metal ones are basically just slats, and they don’t do much to stop sideways rain. I’ve had better luck with adding a simple baffle or even a bit of flashing angled above the vent from inside—just enough to deflect water but not block air. It’s not perfect, but it cuts down on direct hits during storms.
Curious if your insulation is touching right up against the vent itself or if there’s any sort of gap? I’ve noticed that when insulation is packed tight against the vent opening, it tends to wick moisture more easily. Leaving a few inches of clearance (and using something rigid like foam board as a dam) can help keep things drier, though you lose a little R-value at that spot.
Also, what type of insulation are you dealing with—fiberglass batts, blown-in cellulose, something else? Cellulose seems to get soggy faster in my experience, but maybe that’s just regional humidity talking.
I’m always interested in how people balance airflow versus weather intrusion. It feels like every time you improve one side, you risk making the other worse... Have you noticed any mold or musty smells yet, or is it just occasional dampness?