Owners who put in high-end finishes may be disappointed, because “there is no category for superexcellent,” said Roberta Axelrod, the director of residential sales and rentals for Time Equities. While some buyers may be willing to pay more for those finishes, she said, “there is a difference between what the market will perceive as adding value and what an appraiser will determine.”

Once an appraiser has evaluated a home, he or she compares it with similar ones that have sold recently, known as comparables, or “comps.” These should be in the same building, or in one nearby in similar financial condition and with similar maintenance fees, Mr. Miller said. But in Manhattan, similar apartments a few blocks apart can have different values based on proximity to the subway or a park, or whether the building has a doorman or a gym.

In Bedford Stuyvesant, Brooklyn, for example, sales within a few-block radius can range from $250,000, for a dilapidated home to $1 million for a renovated brownstone with original woodwork, said Sam Heskel, the executive vice president of the appraisal management firm HMS Associates.