Sixty homes, ranging in age from less than one year up to 20 years, were selected in the Madison, Wisconsin, area. All had powered humidifiers mounted on a forced-air furnace. The humidifiers were allowed to run when necessary to satisfy the setting on a calibrated humidistat. The running times of both the humidifier and the furnace blower were recorded during December 1983 to March 1984. The houses in this study were surveyed and information on insulation levels, wall areas, window areas, etc., was obtained, along with the living habits of the occupants. A statistical analysis was done to explain the variation in the running time data for the various homes. From this study, it was concluded that most new homes still need additional moisture to maintain desirable relative humidity, although the amount of moisture required has been reduced.