Valuing 2-4 unit properties is a little different. Bedroom count typically drives rent, and income is a main driver of value for income properties. For comparable sales I typically search the MLS by unit count. Using the results I focus on location, bedroom count, actual age, effective age, and condition. Adjusted sales prices ranges are typically wider than that for a single family home. Thus, for the sales comparison approach, appraisers reconcile adjusted sales prices by:
Per Unit
Per Room
Per Bedroom
Per gross building area
I typically give the most weigh to per bedroom given bedroom count drives rent.
For the income approach, rental comparables are identified along with other rentals with similar bedroom count and condition to develop an opinion of market rent. Opinion of market rent is then multiplied a gross rent multiplier (GRM) that is extracted from the market by sales of similar properties. GRM=Sales price/Gross rent.
In a recent appraisal I completed for a duplex I analyzed 23 sales that reconciled to a GRM of 171 and market rent of $3,150 resulting in an indicated value by the income approach at $538,000.