How to Verify Unpermitted Expansion at a Self-Storage Facility Using County Permit and Assessor Records

A storage OM says 78,400 net rentable square feet. The assessor shows 64,200 square feet of improvements. Current aerials appear to show a newer row of buildings behind the original site. That is not a footnote. It is the beginning of the diligence file.

The mismatch may be innocent: assessor lag, a different square-footage definition, or a recent permit that has not flowed through the roll. It may also be unpermitted expansion. Either way, the buyer should not be paying for undocumented income area without knowing which bucket it falls into.

Write down the broker’s stated NRSF, the assessor’s improvement square footage, the square footage supported by permits, and the measured footprint from aerial imagery or survey. Do this before debating value.

If the numbers are close, move on. If broker NRSF is materially higher than assessor square footage, look for assessor lag or unsupported area. If measured footprint is higher than the permit file, the risk is sharper. If assessor square footage is higher than permit history, the county may have picked up improvements that were never properly closed out.

The building department, not the assessor, owns the permit file. Pull original construction permits, additions, alterations, conversions, demolition permits, expired permits, and certificates of occupancy. A permit without a final inspection or CO is not the same as completed, permitted area.

In smaller jurisdictions, expect friction. You may need a public-records request keyed to address, parcel number, owner name, and project name. That delay is annoying, but it is cheaper than discovering after close that part of the rentable area has no closed permit.

Assessor improvement square footage usually updates after the building department closes work, often on an annual cadence. If a permit closed in March 2024, it may not appear until the next roll. If two roll cycles pass and the improvement still is not reflected, the lag explanation gets weaker.

Do not generalize across states. California, Texas, Florida, and smaller county systems handle improvements differently. The right question is always local: how does this assessor receive and update building-department information?

Historical aerials give you the construction window. If 2018 imagery shows 12 buildings and 2024 imagery shows 14, the permit search should explain what happened between those dates. If it does not, the next step is not a conclusion. It is a targeted request to the building department and, where relevant, code enforcement.

Then pull the zoning file. Many storage facilities operate under conditional-use permits or site-plan approvals that cap building footprint, height, lot coverage, or access. A building can have a permit problem, a zoning problem, both, or neither. The files answer different questions.

A strong research output should read like this: “Permit history supports 64,200 square feet. Broker states 78,400 NRSF. Aerial imagery suggests two additional buildings appeared between 2018 and 2023. No matching permit found in the online file. Open question: request complete building and code-enforcement records from the jurisdiction.” That is useful. A yes/no label is not.

Unsupported square footage can affect lender proceeds, insurance, tax exposure, permitting costs, and buyer basis. If 14,200 square feet of asserted rentable area is undocumented, the buyer needs to decide whether that income should be valued the same way as fully supported area.

The goal is not to scare a buyer away from every discrepancy. It is to keep the discrepancy priced correctly. Records do not eliminate the judgment call; they make the judgment call honest.