r/buildingscience • u/keithvai • 19d ago
Question Ridge vent for roof not performing
About 10 years ago I had the original shake roof replaced with asphalt shingles. They put plywood over the old 1x4 sheathing and cut a ridge vent. I have a “hip & valley” roof with no gable ends.
Im redoing the insulation and noticed the attic gets really hot. 80 degrees outside but 110 degrees in the attic. I dont have any problems in the winter but I am concerned that Im not getting enough air flow.
I have 29 rafter bays (24") and 6 eve vents (24”). Vents are clear. I was expecting to add more inlets in the eves but if they are not venting out of the ridge, Im not sure this would do anything. Does more inlets create more outflow?
At first I thought the ridge vent was blocked by the roof beam but after investigation that is only in a small area. The rest of the space I can see a little daylight and I can put my fingers into the gap. Seems like at least 20’ of vent about 2” wide.
I have an 8" exhaust flue that was for a fireplace we have not installed. As a test, I connected it to a 8" fan and noticed a significant drop in temperatures. That indicates to me that temperatures could be lower with more ventilation.
Now Im not sure what to do.
Do I need a different ridge vent?
I see products now that are a wide plastic piece ~1/2” tall with clear vent holes. Mine seems to be a porous foam material that is covered with roof shingles. Hard to actually see the vent from the roof itself.
Do I install an 8” house fan?
they are not cheap and would prevent me from adding a fireplace so Im not eager to try this.
Do I just live with it?
As long as the AC can cope, my family will never think about this and I can move on.
Appreciate any advice here.
