When calculating the square footage of a condominium unit, an appraiser must use:

When calculating the square footage of a condominium unit, using interior measurements is critical because this approach accurately reflects the usable space within the unit. Interior measurements take into account the walls, closets, and any other structural features that are part of the living area, providing a true representation of the space the occupant can utilize.

This method helps to standardize measurements among various condominium units, allowing for proper comparisons and valuations. Many appraisal guidelines and practices specifically advocate for interior measurements, particularly in multi-unit dwellings like condominiums, where the internal layout and space allocation can vary significantly.

Additionally, using exterior measurements could lead to discrepancies due to variations in wall thickness, which does not contribute to the actual livable area of the unit. Overall building measurements pertain to the entire structure rather than individual units, and parcel measurements relate to the land on which the building sits, which is not relevant for determining a specific unit's square footage. Therefore, focusing on interior measurements ensures that appraisals are reflective of the true living space available to residents.