Just discovered during a home inspection that our bathroom exhaust fan vents into the attic instead of outside. Inspector says this is a problem and could cause mold/moisture issues. 😱

How big of a deal is this really? The fan has been like this for 20+ years (house built in 1995) and I don't see any mold in the attic. But inspector says it needs fixing.

Is this something I need to address ASAP? How much does it cost to reroute a vent to the outside? Can I do it myself or need a professional?

Anyone else dealt with this? Did you fix it or just leave it?