the 4" vent is already thru the roof, i have plenty of 8" round duct and also a lot of square duct. i can build anything out sheetmetal and also have a 4' wide roll of that. i few inline 8" fans should give plenty of ventilation. i started this thread to help me from having a lot of trial and error. my room in the attic can easily be hooked to my cooling duct. i know where everything is in this house because i built it myself while working full time in maintenance. then i built my parents house, 3.5 years of 7 days a week. i can do whatever it takes but like i said before im just looking for someone to help me with amount of light per space, tips with getting started, ect... i believe i will build 2 rooms inside the big room in attic, run ac duct to them and vent some heat to attic over house(attic room over garage is separated by wall) which will leave thru both gable vents and the rest out vent in roof. i can get fresh air from gable vent in garage attic. if there is someone out there that would like to help with the specifics of what i need to keep a mother going and clones flowering please feel free to jump in.