Insulating and venting a part hip roof
Renovating our attic to make it a living space (zone 5, 2×6 rough cut douglass fir, balloon frame, ~100 y/o), and we followed some basic suggestions from our roofers and carpenters working with us on the project: rafter vent, insulation, vapor barrier, drywall. We were about to put up the drywall, and checked that all is working fine, except, of course, those rafter bays that don’t connect to both a soffit or ridge vent… mold, of course. Cleanup is underway (vinegar, orange oil, borax; considering mold-resistant paint once it’s dry).
The question we have is, is it REALLY OK to drill 1/2″ holes in our rafters to create vents for the rafters on the hip?
Some say no, it weakens the framing (except this doesn’t make sense since we’re expected to do the same running electric).
Some say keep it centered along the width, to maximize strength, and while insulation will cover holes, it’s permeable, and we’re using rock wool, so breathing will happen.
Some say within the 1″ vent area, so there is direct communication from rafter bay to rafter bay and eventually to soffits and ridge vents. Here’s an example of what one contractor did: https://youtu.be/nbuCgjjVngs
Back to our question (is it REALLY OK to drill 1/2″ holes in our rafters to create vents for the rafters on the hip?), we’re thinking, similar to the video, two batches of 4-6 holes, one toward the top and one toward the bottom of the hip rafters, with maybe a few between spaced evenly along the length. But before we start drilling, is this really OK?
Aside from reconstruction, what other options do we have without tearing down the roof?
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