A super common defect found in home inspections is a bath fan or dryer vented to the attic space. Handymen often think this is a “good enough” solution. In their mind, the warm moist air will naturally exit the attic space through the roof vents. All too often, this is not the case.
Typically, this is a defect I find inspecting after a remodel. The contractor doesn’t want to penetrate the roof and have to flash the penetration and risk creating a leak. But the damage that warm, moist air can do in the attic is almost as bad as a roof leak.
During the summer, everything may be OK; the hot air in the attic wants to escape and the convection current between the gable or soffit vents and the ridge vent carries the moist air out. In the cooler months, problems develop. When the temperature falls, the moist air cools before it can leave the attic. The cold surface of the roof deck gives the moisture a place to condense, and if it’s cold enough, freeze. Then, in the spring all the ice melts at once, leaving the roof decking and even insulation, framing or ceiling wallboard soaked.
Now, we start to get mold and mildew. If it’s bad enough, the roof decking starts to rot. What started as a shortcut to save a few dollars has become a major issue, festering in the dark. The lesson: all vents, be they plumbing, dryer vents or bath fans, need to terminate properly outside the building envelope. Many times, a vent can be run out the gable end and terminated without having to penetrate the roof. If your home inspection finds a defect like this, make sure it gets corrected. And it you have any work done involving vents, make sure the contractor does it right and saves you cash and headaches down the road.