Adding ridge vent and continuous eaves sensible for vaulted ceiling?
I life in the Bay Area (Northern California) in a 1981-built home. The roof is 5/12 with 6″ rafters with vaulted ceilings in several rooms. The insulation is R19. Technically, there are soffits, but most are blocked with insulation. A combination of passive and powered gables do most of the venting in conjunction with a few eyebrow vents. There is no ventilation in the vaulted areas. My guess is that they builder just stuffed them with R19 and sealed them up. In any case, they are not well insulated either. The house has no mold issues, although the attic does heat up and some of that heat radiates into the house all night long during the summers.
The house needs a new roof, which is scheduled for a few weeks out. As part of that, I am considering adding a ridge vent and a continuous eave vent around the perimeter of the eaves. I would also pull the sheathing over the valuted areas and install 4.5″ Thermasheath-3 (~R31) with Smart baffles trimmed to 1″ before replacing the sheathing. The non-vaulted areas would have the same eaves treatment and ridge vent, but the baffles would only extend 3′ or so from the eaves. I then plan to increase the insulation from a poorly laid out R19 (does cover top plates, often mis-cut, etc.) to R30 using unfaced bats or rolls in a perpendicular layout. Finally, I would seal up the eyebrow and gable vents.
Is this sensible? I’m well past the dew point with the 4.5″ polysio, but am concerned that there may be other issues of which I am unaware. Also, does adding the ridge vent and/or continuous eaves make a positive difference? I’m spending not just for economics, but also for comfort, so I don’t need a short-term payback on energy savings. (Although that’s definitely a good thing…)
So, is the above going to make a significant impact? Is it the best approach? Do you have suggestions for things to do differently (or better)?
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