Should dryer and bath fans ductwork pitch outside or back in the house? – GreenBuildingAdvisor

Im trying to help my girlfriends dad out. He ran all his exhausts with schedule 40 pvc pipe instead of ductwork. He connected the inline fans and an additional damper with ferncos. He also has pvc with a ground wire for the dryer vent. All venting is pitched back towards the house instead of outside. Everything exits out a side wall.  This is in Wisconsin. Attic has blown insulation. The inline fan is wrapped with some batt insulation and then from there its about 8ft of ductwork that is not in the insulation as it goes to the outside. This was a new build about two years ago. 

The one bath fan started showing water damage on the inside of the ceiling so I went up there and found all the ferncos held a ton of water and were pretty much ice filled. I since removed everything from the inline fan (the pvc was pretty moldy inside) and used the insulated thermaflex ducting. I pitched everything outside from the inline fan now. On some cold days I guess they are still getting some water dripping back into the bathroom through the fan. 

The dryer – she was running it and it got really hot she said so she shut it off. They are good with cleaning lint out everytime. I assume he ran the pvc down into the wall so im not sure how much i can swith over to ducting for this one. or could i just swith the pvc to rigid duct in the attic and pitch it outside? 

Thanks for any pointers to help fix these problems.