I guess my reason for double top plates are, length. max length I can get is 20' for wood locally. So I need to build walls in multiple sections. Code says I need to stager my top plates for strength, so I figured, double wall plate, have the top plate extend 2' past the 2nd top plate, and I fulfilled my requirement.
My basement measures 8'4" from the cement to the bottom of the floor joists above. So either I have a 1" gap or I do a double top plate, and cut the 8' studs down a half inch? but am open to suggestions of better ideas.
Code changed here in Minnesota in 2015, that now all cold air returns need to be ducted. we can no longer use the space between the studs...
For dropping the return air duct down the wall, do I simply leave a gap in the top plate, or try and cut it out? or does the HVAC person do the cutting?
Intended occupancy is 1 bedroom, 1 bathroom, 1 media room, and 1 family room. I think code states that all bedrooms need to have a supply and a return. My media room will be sealed off from the rest of the basement, so its a separate room. Not completely air tight, but as tight as I can get it without going crazy about it.