Mike, if the market (i.e., buyers & sellers, governmental agencies which oversee housing) is "blind" (i.e., no enforcement, buyers and sellers pay no heed, etc.) to whether or not (for example) the finish in the subject's basement was via the permit process or not--and you cannot find a permit for the finish--may I ask what your approach would be to offering an opinion of Market Value for the subject?
Whether "Blindness" is typical or not, the requisite "Legally Permissible" Use leg of HABU does not magically vanish. When Muncipal ordinance/local Laws exist governing site use and site improvements (Zoning / Building ordinances):
1. identify and confirm
whether a BP and C.O. (via the Building ordinance and or
generic inquiry with the Bldg Dept. re property type, dwelling type, improvement type) is/was required by the Municipality as of the Effective Date of appraisal.
2. review property records for the subject property that exist/existed as of the Effective Date of Appraisal (in person, via online municipal assessment
and building dept. records, via phone confirmation with identified municipal personnel by name, position and date of contact - retained in workfile).
3.
IF required by the Municipality, either the requisite C.O. exists or not. Depending on the SOW (including assignment conditions), utilization of either an EA or HC conditioning the market-extracted contributory value of actual improvements that exist upon Owner, or Client, confirmed legally permissible use of the site "as-improved".
As of an Effective Date of appraisal a subject's site improvements which exist, "as-is", are or are not Legally Permissible.
According to The Uniform Standards of Professional Appraisal Practice, highest and best use is defined as “The reasonably probable and legal use of property that is physically possible, appropriately supported, and financially feasible, and that results in the highest value”.
(It may also be defined as the legal use to which a property can logically be put or adapted, for which there is a current market, and which may reasonably be expected to produce the greatest net return to land over a given period of time, or to yield to land it’s highest present value.)
In order to determine Highest and Best Use, the property must meet the following tests. These four tests are applied in their corresponding order, in other words the test of legally permissible must be met before the test of physically possible may be applied, and so forth.
1) Be legally permissible
2) Be physically possible
3) Be financially feasible, and
4) Be maximally productive
The first test involves a determination of what uses are legally permissible. Existing leases, existing or proposed improvements, deed
restrictions, zoning, building codes and environmental regulations may all influence potential use.