Prior to and even during a bathroom remodel, I often have conversations about tile and fixture layout, style and finish. But the conversation seldom leads to discussion of bathroom ventilation, issues like CFMs, minimizing ductwork and the placement of external heads and backdraft dampers. In my Boston Globe column and on my ConcordCarpenter website, I often receive questions relative to ventilation and mois- ture in bathrooms. Unfortunately, there’s plenty of misinformation about bathroom ventilation. Some folks ask if it's okay to vent moist shower air into a roof soffit or unheated (but vented) attic. Others ask whether they should be concerned about their current “mile-long” plastic duct tubing. Then there are those who complain of having a mystery stain on their ceiling. The stain is the result of a fan pipe that was installed through an unheated attic where moisture built up from a pipe dip, froze, and months later melted, staining the plaster ceiling below. Mystery stain solved! Not venting a shower or improper venting can result in high humidity in the bathroom. When bathroom humidity builds up, warm moisture-laden air moves toward cooler wall surfaces, where it condenses back into water. Moist air can also work its way into a wall cavity and condense inside the wall. Both situations can result in mold, odors and sometimes structural damage. Moisture will also peel off wallpaper or paint. Seeing or smelling mold and mildew is a good indicator that you have a high moisture problem. So how do we remodel our bathrooms and still enjoy that hot, steamy shower and avoid mold problems?
Circulate fresh air and get rid of unwanted moisture.
By Rob Robillard