How to Insulate a vaulted ceilng (w/ odd roof add on)
So I’m doing some major renovation to my brewpub and will be opening up a vaulted ceiling. This is an old road house style building, I think a residential home at one time with many additions, most done very poorly over the last probably 80-100 years. And now it’s all one large restaurant/brewery. This in the NY Catskill area, just making zone 6. I’ve been gut renovating sections at a time and now is the entire front of the building where I need to vault the ceiling. It’s about 50×23 with conventionally framed single gable roof with 2×6 rafters 24oc. What gets complicated is that a larger roof was added over the original roof. They sistered rafter add-ons to one side of the gable and then there is a series of rafters that go up and over the other gable side with purlins and such all the way over the rear addition. So what I’m left with is this smaller gable framing within the attic of this newer system. One gable is part of the (newly) roofed exterior and the other gable is in the attic. I cannot figure out how to best insulate this vaulted ceiling. Initially I was going to install baffles and build down the rafters to fit R30C fiberglass and then a continuous layer of foil faced polyiso on the interior. But the ridge of these gables would just vent into the attic, not outside. Or I can skip batt insulation and just install staggered layers of rigid foam on the inside? I have a few sources for reclaimed foam. There will be no lighting or mechanicals in the bays so I can be done pretty airtight. Spray foam is really out due to cost. I am not looking for the absolute best insulation value in the world as anything is better than what has essentially been zero in this building. I just don’t want to cause any problems. I’ve attached a crude pdf to better illustrate the construction. Thanks so much for any direction.
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