I learned that I'm actually dealing with two departments: one is Planning, which ensures that such things as zoning and setback requirements are adhered to (which will be a breeze), and the other is Building, which is where the extra scrutiny will occur.
After a couple of hours at the counter with a building department rep, I became aware of some red flags in my plans:
- The bottom of my outer leaf door is too high. I think I need to either lower the outer door and move the inner door farther inside by another 8-12" to accommodate there being a "non step" plus a step in the space between the doors, or have a 3' x 3' "pad" outside the outer leaf door. As much as I hate the idea of losing any more footage in the room, I'm leaning towards moving the inner leaf door a bit to accommodate the steps between the doors.
I need "fresh air" ventillation. This is because the room is considered "habitable" (even though it is not going to be a bedroom). If this were going to be a shop, it would not need fresh air (e.g., a window). However, because the room is going to be equipped with a permanent air conditioning unit, it cannot be considered an uninhabitable shop. Therefore, I need to have a window (no freakin' way!) or some kind of exhaust/fresh ventillation system. This is quite disappointing, as the only way to do this is to compromise my walls or ceiling. What I was thinking of was an incoming vent that would pull air from the ceiling of a faraway room of the house (I'm thinking the living room) and into the ceiling of the studio, and an outgoing vent that would push air out of the house (I'm thinking the back of the house, an area where the roof peaks and will be close to where my mini split A/C lines will be penetrating the outer back wall). The ducts would make a number of 90-degree turns along the way.
I also need to provide 1/2" EPDM 60 duro specs that prove its weight limits in PSI and its fire retardance authoritative sources.
Hot mopping is probably not required, but some kind of sealant will be required. I'll need to research this and specify what I will intend to use.
The ventillation objection is significant, and one that has got me rethinking my A/C plan entirely. Recall that my primary purpose of going with the mini-split was to avoid cutting big holes in my ceiling, and here I am cutting big holes in my ceiling anyway. Perhaps there is a way for me to incorporate a combination A/C-and-fresh-air system in the same ducting.
I'm sure there are a bunch of you guys thinking "I told you so!" regarding the "lack of fresh air" drawback of the mini-split.
I'll be giving one of my HVAC guys a call later today to get some advice... Meanwhile, please share any ideas or suggestions you may have.