The best thing a homeowner or broker can do to help the appraisal process is to prepare a one-page sheet for the appraiser that outlines the changes and repairs that the home has undergone since it was bought, Mr. Miller said.

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 f

Before anyone can buy a house with a loan from a bank or refinance a mortgage, the lender needs an objective assessment of the property’s value — after all, the home is the bank’s collateral for the loan. Assessing the value is the job of the appraiser.

You may or may not incur these costs when you buy (or during the time that follows), but many, many people do. And, once again, as a culture we rarely plan and budget for these expenses.