Thermal roof inspection is one of those services where timing matters enormously. The same roof scanned at the right hour in the right conditions yields rich, defensible data; scanned at noon on a hot summer day, it produces noise. Here's how to schedule it correctly.
Time of day
Almost always after sunset. Wet insulation holds the day's heat longer than dry insulation, so the thermal contrast that reveals moisture is strongest during the evening cooling cycle. Daytime scans suffer from solar loading and reflection that hide real anomalies.
Time of year
In North Carolina, late spring through early fall offers the most consistent flight windows. We avoid scanning within 24-48 hours of significant precipitation (it can mask anomalies) and prefer dry, calm evenings.
How often
For active commercial portfolios: annually. For roofs nearing the end of their service life: more frequently, especially after major weather. For acquisition due diligence: at least once before closing.
Event-triggered scans
Schedule a thermal scan after any major storm (hail, wind, hurricane), before any major roof capital decision, when tenant complaints suggest envelope issues, and any time visual inspection shows damage but you suspect more is hidden.