Enter an life in this column, and a age in the preceeding column, ONLY if you want to use straight-line depreciation (calculated from this age and life) to depreciate the component using a different percentage than this overall percentage.
If you leave this column blank (and also leave the depreciation percentage and effective age columns blank), Residential Estimator automatically sets the depreciation percentage to one of the following:
Main Residence: If the component is for the main residence, Residential Estimator uses the depreciation you set on the Building Data screen.
Garage or Basement Section: If the component is for a garage or basement section, Residential Estimator uses the depreciation you set for the section on the Garage/Basement screen. If you did not set a depreciation percentage or an age and life on the Garage/Basement screen, Residential Estimator uses the depreciation you set on the Building Data screen.