What are the three types of depreciation in real estate appraisal?

The three types are physical deterioration, functional obsolescence, and external or economic obsolescence. Physical deterioration is wear and tear from age and use, like a worn roof or faded paint, and can be curable or incurable depending on repair cost. Functional obsolescence results from outdated design or features, such as a home with only one bathroom or an obsolete floor plan, and may be curable or incurable.