Broan Recessed Ventilation Fan Light, 70 CFM

My wife and I were shopping for a bathroom fan that looks good, is quiet, and keeps the bathroom dry after long showers. My bathroom requires a fan rated for 64 CFM minimum. We selected the Broan 744 with a rating of 70 CFM. The fan is quiet and the recessed installation appeals to us. Shortly after installing the unit, however, I noticed that long showers resulted in moisture on the ceiling. I went up the attic to inspect the installation and re-taped the exhaust duct to the unit for a good seal, and also re-positioned the attic insulation flat/against the top of the ceiling sheet rock to minimize condensation due to the cold air in the unheated attic and the warm bathroom. This helped alleviate moisture on the bathroom ceiling after showers. My only recommendation to readers is when determining minimum CFM required, note whether your installation is ideal per Broan instructions. If not, consider purchasing a fan that exceeds the minimum required CFM. For example, if you use a corregated duct in lieu of sheet metal, or have an additional 90 degree turn or elbow, don't hesitate to select a fan with a higher CFM. The Broan 744 has been installed for nine months and is meeting my family's needs and expectations.