(Forbes.com) – Leslie Sellers, a certified general real estate appraiser in Knoxville, Tenn. and president of the Appraisal Institute, an organization of professional real estate appraisers, has seen some unusual properties in his 30 years evaluating homes. Appraisers use “comparables”–similarly appointed properties that have recently sold nearby–as part of the valuation process, but in the case of dome-shaped houses, A-frames on six-acre tracts or subterranean homes with earthen ceilings, Sellers has had to get creative. He has scoured national listings for sales of homes with similar designs, then adjusted for differences in the market.
In an unstable real estate market, this kind of detective work is crucial. It also requires special expertise. The highest professional designation for appraisers requires three years of training, extensive post-college coursework, multiple exams and 4,500 hours of experience.
Even for the most qualified appraisers, the job is getting harder. Foreclosures have driven sale prices down, and there are fewer non-foreclosure sales for appraisers to use as comparables. Homes may be sold below their value; and appraisers must control for these cases.