Two recent posts from my friend Jamie Owen at the Cleveland Appraisal Blog plus a planned realtor office visit inspired me to write this. Jamie did a great job blowing up the myth that comparable sales need to be within one mile of the subject in this post. He also tackled geographical competency, or the need to have boots on the ground knowledge about a market in order to credibly value properties in a second post.

Both posts touch on the subject of what is a comparable sale and why should anyone in real estate, or even the general public, care? The quick answer is that “comps” are the basis for how we, both those in the real estate industry and the man on the street, value residential real estate.

Per the Dictionary of Real Estate Appraisal, 3rd Edition, comparables are:

“…similar property sales, rentals, or operating expenses used for comparison in the valuation process; also called comps.“

Comps are used in the Sales Comparison Approach to Value, especially in residential real estate appraisal. All of us, appraisers, real estate agents, and folks considering buying a home, use the theory of substitution to determine the value of a home. What would the typical buyer shopping in that neighborhood buy instead of the subject?

A comparable sale is a sale of a home that the typical buyer of the subject would buy instead of the subject.

Subconsciously, everyone who owns a home compares it to homes in their neighborhood. We learn about a recent sale on our block and place a price on ours based on whether we think it’s better than ours, relatively similar, or inferior.  The formal version of this is the sales comparison approach used by appraisers.

We appraisers find the most similar sales, adjust the comparables for differences from the subject, leaving each adjusted comparable sale an indicator of value for the subject. The vast majority of single family residential appraisals in the US rely upon this methodology.

In the context of the sales comparison approach to value, the key is to identify the comps for the subject.

The easiest way to get the value of a single family residence wrong is to get the comps wrong!

As my mentor George Dell says, “What does similar mean?”
(Now go subscribe to his blog. He’s really smart. Then take his classes)

Residential real estate, such as a house, a condominium, a home on a small acre lot outside of town, etc., have characteristics (“dimensions”) that serve as descriptions of a specific sale for a specific property. The more similarities between a sale and the subject under consideration, the better a comp. We can go into a deep dive, like George does in his classes; instead, I want to talk about what I do specifically for simple single family residential work in conforming neighborhoods.

Some examples of dimensions and characteristics important to valuing homes include transaction terms (financing, credits, etc.), motivations, location, views, quality, design, condition/age, floor area, and amenities.

Some dimensions/characteristics are more important than others and can vary dramatically in importance depending upon the location. For example, pools are valuable in the Sacramento region but have less value in the Pacific Northwest where the weather is cooler. Basements are common in the Midwest and East Coast but not so here. In the Whisper Creek Subdivision in Arbuckle, CA, a tract of large homes on half acre lots, RV parking is a significant factor unlike other nearby markets. This is why the geographical competency that Jamie discusses is so important. Appraisers with geographical competency understand what characteristics define a true comparable and get the subject’s value right.

Time usually matters except when it doesn’t. If a market is rapidly changing, using the most recent sales can reduce the impact of market change. When a market is relatively stable, time is less important and so using older comparables is reasonable. I downplay time frequently because time is usually the easiest and most reliable adjustment to make.

For a typical tract home in my area, the most important factors are motivations for the purchase or sale, time, location/proximity, and size/floor area. I start with a map search using my neighborhood boundaries and go back 12 months prior to the date of value for closed sales. I exclude from consideration REO sales, short sales, and other transactions where motivations likely had an impact on sale price.

I search for homes a little smaller than the subject because most buyers can make do with a slightly smaller home. Because the typical buyer can accept a larger home than the subject, I set the upper boundary on my floor area range wider than the lower bound. For example, if the subject has 2300 sf of living space, I will search for comparables with 2000 sf to 2800 sf of living space (300 sf smaller to 500 sf larger).

After I set my criteria in the MLS search, I run the search and review the results.

I mentally draw a box around the subject’s important characteristics so I can place it in the competitive market. This is known as bracketing. Reasonably, would the typical buyer consider the sales found suitable substitutes for the subject? Are the sales similar in quality and design? Are there differences in lot size or age? Do I have larger and smaller homes? Do I have homes in similar condition, or inferior and superior? I try to account for every significant characteristic of the subject so I can show, by comparison, the value of the subject by using these comparables.

If I’m comfortable with the sales found, I can start my adjustments analysis. If not, I revise my search criteria and run the search again until I am happy that the sales found reasonably describe the subject.

Once I have my initial candidate comparable sales identified, I dig in and look for most representative comparables of the subject and decide on which sales to research further (view the exterior, contact agents involved in the transaction, etc.). I review outliers, sales outside the normal range, and try to determine why the sales deviate from the norm. I either adjust for the issue or remove the outlier from consideration. The remaining comps, after adjustment, are my indicators of value for the subject.

Comps are usually easy to find in conforming neighborhoods as long as the subject is similar to the rest of the neighborhood. When the subject is unusual, or when there are few sales available and they are all different (“non-conforming”), comparable selection is difficult. The appraisal becomes complex and beyond the scope of this article. I do have tips in my article about appraising complex residential properties.

How do you search for comparables? What are some tips for a real estate agent or new appraiser you can share?