patrick.net

What is the sq ft of the house, and what are the going price of similar houses in the neighborhood?
As for what they put in home repairs in the last 4 years, don't for get that remodeling has been a high retail mark up business for most the last 10 years.
What were the improvements, were they physical additions, or remodel and refurb jobs?
Most home improvement jobs are a lot cheaper now than 4 years ago.
You can get a marble counter now for 1,000 or so, they were at least 5 to 10K.
Labor is cheap now, especially construction labor.

What was the value of the house in in 1972 new, 1985 and 1999?

I would plot a line from three values and project what it would have been ignoring the bubble.
Then consider the work done in today's prices, and then consider the usage value from there.
What you spend is not always relate to the value it adds.

Fixing Curb appeal by adding a 5K landscape overhaul adds a lot more value, then spending 25K on a drop ceiling in the den with recessed lighting.

T'nounce has much more experience than I do and much more practical knowledge. I just wanted to offer what I've noticed on Zillow: they refer to public records and use their proprietary algorithms, but they are subject to the "garbage in garbage out" principle. For instance, my house is listed with 2 extra bedrooms (don't I WISH I had 5 bedrooms!!!) and two other houses on the street are listed with 5 beds, but one is the 5-bed plan and the other is a 4-bed home with a 1-bed mother-in-law unit out back. I think the values of imaginary bedrooms vs. a real bedroom vs. a possible rental unit should be very different, but we're all lumped in pretty much the same.

Interestingly, despite fairly uniform Zestimates of ~$250k in the neighborhood, a much nicer/newer/bigger house than mine has been sitting forlornly at $210k with no takers since January. (At least 4 homes are bank owned and just sitting vacant, not for sale, not rented, just sitting.) I'm inclined to believe Zillow needs a lot of improvement before you can really rely on it.