For single family homes, there are two basic methods used in real estate appraisal. They are replacement cost analysis, and using comparable sales. A third appraisal method, based on capitalization, is used for income properties, and is covered in another article.

In figuring replacement cost the question is: What would it cost to buy this land and put this house on it? If the land (improved) would cost $40,000, and the house could be built for $150,000, the value indicated would be around $190,000 - if the house is fairly new. If it has used up 10% of its useful life, you can deduct $15,000 for depreciation.

Replacement cost is not really a very useful measurement. It is difficult to say what the land is worth in a city center where none is left for sale, for example, and tough to gauge depreciation. It is used as a secondary method, and for unique homes that can't be compared easily with others. The primary method of real estate appraisal used for homes is a market analysis using comparable sales.

Real Estate Appraisal 101

To get a good idea of what a home should sell for, you need to compare it to homes that have sold. Find at least three similar homes in the same area that have sold within the last year, preferably within the last six months. This information is available in the county records, or from a real estate agent with access to the MLS (multiple listing service).

Now the confusing part. You start with the selling price of each of your comparables. If your subject home has a second bathroom, and the a comparable doesn't, you add the value of the bathroom to the sales price of the comparable. If a comparable home has a blacktop driveway, and the subject home doesn't, you take the value away.
 
You are rectifying differences, to see what comparable homes would have sold for if they were like yours. So if a comparable sold for $140,000, and a bathroom is worth $15,000 in your area (ask a real estate agent for help with these figures), you ADD $15,000 for the bathroom it doesn't have. Then you subtract, say $4,000, for the paved driveway it does have. This gives you a comparable sales price of $151,000.

You do this with all differences between the subject home and each comparable. When done, you average the three comparable prices. So if the three comparables have adjusted sales prices of $151,000, 162,000, and 149,000, you add the three figures and divide by three. The indicated value of the home is $154,000.

Of course all appraisal is an inexact science. If you can only find comparables sold over a year ago, you have to estimate appreciation in the area. If one sold with seller financing, you have to decide how this affected the price. For all of it's flaws, however, for single family homes, this is the most accurate method of real estate appraisal.