Simply put, it doesn't take customization into account. Zillow cannot be considered a reliable source for home value. It has it's benefits, but home valuation is not one of them. Location and size are two factors Zillow uses. There are numerous threads here on Zillow.

No, zillow doesn't take customizations into account.

Yes, you are going to be surprised how little value that adds to a real appraisal.

I can't seem to make heads or tails of Zillow. The house beside of ours is priced $65,000 less than the exact same house around the corner. Both are located on cul-de-sacs. Both have deeded boatslips. Both are three car full brick homes with the same floorplan. However the one which is priced less has a full basement! Go figure...didn't realize that a walk-out basement could actually devalue a home. The only difference is that the one that is priced higher just sold about 9 months ago and Zillow has its estimated value the same as the sales price. I wonder why it doesn't believe that the other house would sale for a similar price? It seems that in my neighborhood nearly every house is priced about $100,000 less than what they are selling for. Could that be because we are on a lake and Zillow doesn't care about that? The other houses in our zip code are rural and usually sell for $300,000 less than the lake neighborhoods, but of course this brings down the zip code average price.

Your problem is.... trying to make sense of Zillow. It is a waste of time. Your house (or your neighbors) value as shown on Zillow is not important. Best advice, don't look at it.

Zillow is just a computer program. It doesn't necessarily know about all the features you are talking about. It takes its data from county records, which may not show all of the pertinent information.

Also agree that no one should use Zillow to determine value .. Zillow has the value on my house higher than anything locally has sold .. I laugh every time I cat an update from them.

Speak to a real estate agent and have them run comparables, then you'll have a better idea of value.

I've found Zillow to be moderately accurate for my area, and I find it useful for getting a rough idea about costs in other neighborhoods, but expecting it to magically take into account things that you think are important just isn't realistic. I once had 5 realtors tour my house and do appraisals prior to selling and got market estimates that ranged from $715k to $865k, so don't be surprised when Zillow doesn't nail it. It's just a computer program that tries to use available public data to make estimates.

Quit wasting you time with Zillow!

About 10 years ago we sold a house that was custom built in a neighborhood with tract houses and although there was a slight adjustment for some features it didn't appraise for anymore than the tract homes in general. It is the unfortunate part of choosing to build a custom home in a tract home neighborhood.

Now zillow isn't accurate in any case and I wouldn't take much stock in it at all. In TX a lot of the values come from the tax appraisal which isn't a good indication of value in all counties/cities around here and in some it can be very close. Actually my house doesn't even show up on zillow and it was built 2 1/2 years ago.

"How does Zillow take in account that a house is custom vs tract built? "

It does not.

It simply reports the prices of houses within a distance of another.

They may or may not be comparable.

It ASSUMES that they are similar in value if they are nearby.

I live in a small infill development in a larger less expensive area.

I have the only house in the infill that has a yard and was not built with the others.
They are all mid-702, mine dates before 1935.

Zillow will list the infill houses and the larger neighborhood houses (1950s) as the same 'group.'