Infrared Roof Scanning - When It Works in San Antonio and When It Doesn't

Infrared (IR) thermography for commercial roofs works on a straightforward physical principle: wet insulation retains daytime heat longer than dry insulation. When the roof surface cools after sunset, the areas over wet insulation stay warmer - they appear as warm spots in an IR image taken during the early nighttime cooling window. That thermal signature allows an IR scan to map moisture distribution across a large roof surface faster than core sampling alone.

The limitation is that the thermal differential between wet and dry insulation is only visible when the ambient temperature drops enough at night relative to the daytime heat load. In San Antonio, that temperature differential is significant from October through February. During the July and August peak heat months, nighttime temperatures regularly stay above 80°F, and the entire roof surface retains heat at roughly similar levels - wet and dry insulation are nearly indistinguishable in the thermal image. Trying to do IR scanning in August in San Antonio produces data that is difficult to interpret and easy to misread.

At Commercial Roofers of San Antonio, I use infrared scanning as a tool within the appropriate seasonal window and in combination with core sampling for verification. IR is not a replacement for core sampling - it is a prioritization tool that helps us place core samples in the most informative locations on large roof surfaces. Understanding what IR can and cannot show is the service.