Do Home Appraisers Use Zillow?

Zillow, Realtor, Trulia, and Redfin are some websites that come to mind when buying or selling real estate.

They provide public access to the data that once was only obtainable by licensed real estate professionals through the local multiple listing service (MLS).

But are these sites used by home appraisers? Keep reading to find out. 

Zestimate and Other Estimators 

Each of the previously mentioned sites has its own property estimator.

Pioneered by Zillow, the Zestimate is probably the most well-known.

These estimators work similarly to what an appraiser does to find a property’s value. They use comparable properties that have sold recently in order to estimate the value.

They compare size, room counts, lot size, and other characteristics to the property in question in order to come up with an idea of the property’s value.

Of course, this is an oversimplification of their complex technology, but you get the idea. 

Zillow Estimate Accuracy

These estimators can work great in areas with many similar sales nearby, like in tract neighborhoods where only a few models exist.

Zillow and other websites will often have fairly accurate results in these situations.

The problem arises when the property is unique or in an area with limited nearby sales.

This is where you start to see the fatal flaws of these estimators.

They can only work so well when there is limited data because their core algorithm relies on large amounts of data.

In situations like this, the values are often way off from what an appraiser would value the property. 

Do home appraisers use Zillow?

The question arises then, do home appraisers use Zillow? Yes, and no.

When giving a fee quote estimate on a property, I always google the address and pull up the first few pages (Usually some combination of Zillow, Realtor, Trulia, and Redfin). 

I’ll use the estimates on these websites to see the range of the values to give me a good idea of what the property may be worth. 

They also have the relevant information needed to get an overview of the property and its characteristics.

This is the extent I or any other appraiser should use Zillow and other real estate aggregators.

They are great for getting a general idea of the property, but there are much better places for home appraisers to get their data and a much more professional way to value a property.

Multiple Listing Service (MLS)

Real estate appraisers and real estate agents have access to what is called the multiple listing service, or MLS for short. Every region across the United States has some variation in its real estate market. 

The MLS is where most of the real estate transaction data is shared for members to access. Listing, sales, and leases are all on the MLS. 

Most have a full page of information on the property, and many have attached documents like floor plans or other relevant information.

MLS systems have a considerable amount more of information than a Zillow listing, and they are where appraisers should get the bulk of their real estate data for use in the appraisal process. 

Sales Comparison Approach

When estimating the value of a house in an appraisal report, an appraiser will almost always use the Sales Comparison Approach. 

This process consists of finding comparable properties like your house and adjusting positive and negative dollar amounts for inferior or superior characteristics. 

So if your house has a 5,000 square foot lot, and the comparable has a 6,000 square foot lot, then the appraiser may adjust $10,000 for the difference. 

This is all done in a grid that looks like this:

The Sales Comparison Approach is far superior to valuing a property than a Zillow estimator and is the method most appraisers use to value a house. 

Conclusion

While Zillow and other real estate sites are great for getting a general idea of the value and characteristics of a property, real estate appraisers do not and should not rely on them for the value in their appraisal reports. 

They are a great way to see the value range ahead of the actual appraisal process, but they will never be used by a home appraiser as an indicator of value in a home appraisal.

Founder, Principal at Realvals
Austin Fernald writes about the Bay Area and Northern California real estate market, as well as the real estate appraisal industry as a whole.
Austin Fernald

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