Vents, vents and more vents … last month we talked about plumbing vents. This month, let’s discuss exhaust vents. The purpose of an exhaust fan vent is to remove moisture from the interior of the home. However, many exhaust fans don’t remove the moisture, but put it right back into the home. And in too many homes, the exhaust fans are not installed in the correct location. The two main types of exhaust vents are for the bathroom and / or laundry room and then in the kitchen over the cooktop or range.
A bathroom and laundry room exhaust vent fan is designed to move the moisture to the exterior. Many bathrooms will have an exhaust fan in the toilet room, but not in the area of the bathroom where there is a tub and / or shower. The exhaust fan in the ceiling is to be connected to a duct that is then connected to the exterior. Older homes commonly have the duct venting directly into the attic or over to the soffit. The soffit contains holes / screens through which air enters the attic that is to flow up to and out the ridge vents, turbine vents, power vents, or static vents. Think about it … if the exhaust air from the vents is directed to the soffit to go outside the house, then the air intake in the soffit will reverse moisture back into the attic. Another common deficiency is that the exhaust fan has no ductwork at all installed and insulation is blocking the exhaust port that renders the exhaust vent fan almost useless.
Exhaust vent fan ducts should be connected from the fan housing itself to a vent in the roof decking or an exterior wall. The owner of a new home I inspected recently had already hired some technicians to install some speakers and fans in the ceiling. They broke ducts in the attic while working in the attic. Do you think they repaired what they broke? Happens all the time. In addition, technicians will mess up the insulation and then fail to redistribute it so that the coverage is still uniform. Broken, disconnected, or crushed ducts can be easily repaired.
Kitchen exhaust fans remove moisture and other grease / vapors from cooking. Many exhaust vents merely recirculate the exhaust right back into the kitchen. If possible, these should be vented to the exterior. The vent screen(s) should be cleaned periodically to remove the grease and dirt build-up. The vent pipe and ducts must be securely sealed at the port on the appliance and on the vent in the roof decking to prevent moisture leakage.
To inspect the exhaust vent ducts, get a good flashlight and be careful moving around in the attic. In some attics the ducts may be difficult or virtually inaccessible to reach. Repairing exhaust vent ducts may or may not be too difficult given the design of the attic and accessibility where needed. If you have a handyman repair something like this, the labor charged will be based upon the difficulty of the job. Be safe in the attic and well-ventilated my friends.
