A house lacks central air conditioning in an neighborhood in which central air conditioning is the norm. It costs $5,000 to install the air conditioning. The ensuing increase in the value of the property is expected to be $4,000. This house has incurable functional obsolescence because the increase in value is less than the cost to cure.
A house needs new carpet and interior paint. The cost to cure is $8,000 but the expected increase in property value is only $5,000. This house has incurable physical deterioration because the increase in value is less than the cost to cure.