Your temps are around 90? My friend is having a similar issue. The outer room is hot no ventilation (discretion from nosy neighbors). I have heard of bad things happening when people vent into attic, mold etc. Be careful and get advice from multiple sources since there are a lot of growers. My friends exhaust is on one of the light and has duct going to fan on ceiling and venting out into exterior room. He has a 4" inline with a 250w hps and LEDs. We live down south so it is humid and hot. He has a 5000btu ac inside the grow room to keep babies cool. Temp still ranges from 82-88 with lights on. Next grow he is changing to night time to better keep temps down while upgrading to a 6" for 2-250w hps's. He has fans cooling the canopy and a box fan blowing air at the babies.
Also, he is growing sativa so it is more heat resistant and in veg he never runs the air and they look amazing!!! So lush and dark green from FFOF. He only uses Fox Farm products and is happy with the results so far. Need more lights though so his lighting will change with the exhaust. Maybe 2-3 250w HPS (one per baby).
Always keep air moving and fresh air. Good luck!