Property Valuations
The are several ways appraisers use to come up with an appraisal of a home;
The sales comparison uses sold properties similar to the property in question within a certain area and time to come up with a current value of your home based on the principle of substitution.
The cost approach would calculate how much the home would cost to rebuild from scratch at that time of the appraisal.
The income approach is used for properties purchased for investment purposes.
The Local Property Market
The local property market can make an appraisal easy or difficult depending on the current supply and demand within that area.