Kathleen, the value is, like many other variables, based on the individual characteristics of the subject property. In and of itself, detached versus attached may not be the strongest factor in owing a home in San Francisco. For instance, a block of homes that are all detached except for one home (lets say on the corner) might reflect similar values for all the attached homes, but a higher value on the one detached home. This is, of course, given that the detached home is in similar or better condition that the rest of the row of attached homes. However, again, if one of the attached homes has an unencumbered view, and has fit and finishes that clearly outshine the one detached home on the block, then the factor of attached versus detached becomes less of an important value - generally.