Independent state-certified real estate appraisers, qualified commercial architects, and specialized space planning engineers using ANSI/BOMA standards can provide building area calculations (rentable vs. usable) for CRE. For SBA 504 loan compliance on mixed-use properties, lenders require calculations formally certified by a state-licensed commercial appraiser within the property appraisal report to verify that your operating business occupies at least 51% of total rentable square footage.