What Is Superadequacy?
Superadequacy is a form of functional obsolescence where a feature or system exceeds what the market actually wants or needs — meaning its cost is higher than the value it contributes.
Example
A home with an oversized commercial-grade HVAC system for its square footage has a superadequacy: it cost more to install than it adds to the home's market value.
Why It Matters
Appraisers deduct for superadequacy in the cost approach, since a buyer generally won't pay extra just because a feature was expensive to build.