We go under the house, moisture-map the joists and subfloor, check the vapor barrier and vent situation, and look at any ductwork or equipment down there. Because crawl spaces are enclosed and hard to see day to day, we take extra time here compared to a room inside the living space.
Where we find active mold or elevated moisture readings, we sample and send it to an independent lab, which reports back on spore count and genus. We combine that with what the crawl space itself is telling us about airflow and moisture to explain what's driving the problem, not just what's growing.
For rental properties, we can time the inspection around a gap between bookings, so there's no disruption to a paying guest and the report is ready before the next reservation. We'll also note anything worth flagging to a property manager for the next scheduled turnover, even if it doesn't need immediate attention.