When an appraiser measures the area of a house, they would use the:

When an appraiser measures the area of a house, using exterior dimensions is the most accurate approach for determining the overall footprint of the property. This method encompasses the total space the house occupies, allowing appraisers to assess its value based on the full volume of usable area as measured from the outside walls. This is particularly relevant in real estate, where property listings typically report the total square footage based on exterior measurements rather than interior space, which can vary due to wall thickness and design elements.

Utilizing interior dimensions might misrepresent the size because it does not include wall thickness, which affects how much actual usable space is present. Floor plan measurements and blueprint specifications can provide detailed information about room sizes and layouts, but they are not as universally applied in determining the marketable area for appraisal purposes as exterior dimensions are. Therefore, relying on the overall external dimensions gives a clearer and more comprehensive view for valuation in the real estate market.