Do all exhaust fans need to be vented?

Yes, all exhaust fans must be vented to the outside of the building. This is to ensure that the air being exhausted is not recirculated back into the building, which can cause a buildup of contaminants and reduce air quality. Properly vented exhaust fans also help to reduce humidity levels, which can help to prevent mold and mildew growth. Additionally, venting exhaust fans to the outside helps to reduce noise levels inside the building.