Hello all~
I am a long-time reader of FHB, but homeowner newbie in Pittsburgh, PA. The roof is currently being replaced as I type this – complete tearoff, new iceguard, new flashing, IKO 50-yr shingles, ridge vent, new soffit and fascia. The ridge vent is continuous non-mesh type, and runs the entire length of the attic, and stepped back about 3-4′ from the gable ends. Soffit and fascia are being installed this week, so the work is nearing it’s end.
Here’s the question – the soffits do not have existing vents so the vents are being cut in now. The house has very deep eaves, and the windows are set high on the wall, so it was impossible to box the eaves so that the soffits are parallel to the ground. In other words, the soffits are installed parallel to the roof line. Do I need larger holes for the soffit vents? The contractor is drilling in 2x 1-1/2″ diameters holes approximately every 4′ (5′ ?). As a newbie, I will need some really good arguments to tell him how to do his job if larger holes are required.
The attic right now is insanely hot (112F yesterday, probably higher today), and I will need to install portavent chutes to increase the airflow, as the fiberglass batting in the attic floor rolls all the way to the rafter tails (at least it does not pack into the eaves – I can see a slight amount of daylight in the rafter pockets that have the soffit holes drilled in).
And two other questions… Should portavent chutes be installed in EVERY rafter spacing, or just the ones with the soffit vents? What is the recommended grade/rating of masks to wear when working with fiberglass batting?
Thanks in advance!
James J Rogers
Replies
The soffit and vents can be on bottom of rafters, noneed for it to be run level.
But the size is not nearly enough. A venting system should provide continuopus air flow in every rafter bay. It will be far less effective if it is not balanced - in other words, the same amount of air must be able to flow in at bottom to replace the amt of air that flows out at the top.
The recommended amt of ventilation in most places is one square foot of venting for every 100-150 sq ft of living space. There are 144 sq inches in a sq ft and by the time you consider the restriction on the grill cover of the 1-1/2" pop in vent, you have one inch or so is all - and he is spreading them out four feet apart?
You can get those pop ins up to 4" diameter and you might be needing at least a couple for each rafter bay.
Most of th e time, it is easier and less expensive to use continuous soffit vent
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