Where to vent bath fan

The roof mount exhaust is 5-10% more efficient at removing warm, moist air (hot air rises) than a side mount one. Roof terminal should have a pipe neck attached for a positive connection. Use straight pipe (metal or PVC) whenever possible, wrapped with insulation. Corrugated, flex, pipe creates turbulence and has almost double the surface area for water exhausted in baths to collect on. Use as few bends as possible, and 45s* instead of 90s*. Tape metal joints with silver tape, not duct tape (4 year life). Use hose clamps or similar, and a screw on topside of metal joints. Use HVAC black tape for plastic covered insulation. Insulate the whole pipe and the fan box. Use caulk to seal the small gaps at the fan to wallboard joint. Let no heated moist air into the attic which would cause mold, mildew, wet other insulation (defeating its purpose), and even make frost in your attic. Be safe GBAR