I'm remodeling a small bath next to my HT room. I need to add a room vent (in ceiling) for the bathroom. Right now I'm in the framing stage. The main trunk line for the heating/air system is 10 feet away, and I have a clear path via floor joist to tap into the system. I know I'll need the insulated ductwork and a ceiling vent, and the appropriate tape (not duct tape ironically) to seal everything. I'm looking for the proper procedures to do this small project. What's the best way to tap into the trunk? Should it be accessed from the top or side? What size duct is needed for a 4' X 10' bathroom on a short (10') run? Anything else to watch out for? Thanks.