How temperature differences can reveal moisture beneath a commercial roof

Infrared thermography can help commercial roof inspectors spot temperature patterns that may point to trapped moisture before visible leaks appear. Jaymar Roofing in Slidell, Louisiana, says the technique works best when paired with physical inspection and careful interpretation of weather, roof construction and timing.

Why it matters: - Moisture trapped beneath a commercial roof can go undetected for long periods even when the membrane looks intact. - Hidden moisture can reduce insulation performance, damage roofing components and complicate restoration planning. - Finding affected areas early can help building owners decide what needs repair, removal or further testing before a larger project moves forward.

What happened: - Jaymar Roofing in Slidell, Louisiana, outlined how infrared thermography can reveal temperature differences that may indicate moisture inside a commercial roofing assembly. - Owner Jules Albert III said infrared inspections can identify temperature patterns that suggest moisture, but a temperature difference alone does not prove a roof is wet. - The company said commercial roofs face rainfall, UV exposure, temperature swings and other conditions that can slowly weaken performance and allow water intrusion around seams, flashing, penetrations and other weak points.

The details: - Infrared thermography uses specialized cameras to detect infrared radiation and turn it into thermal images. - Thermal images show apparent surface temperature differences through color or shading. - Unlike ordinary photography, infrared imaging measures thermal characteristics, not visible light. - Wet roofing materials may absorb, retain and release heat differently than dry materials. - In some systems, moisture-containing areas may cool more slowly after sunset than surrounding dry areas. - Infrared cameras do not see through roofing materials or directly measure how much water is beneath a membrane. - The cameras detect radiation from the visible surface, which can provide indirect evidence of what is happening underneath. - Inspection timing matters because daylight, sunlight and sunset all change roof temperatures. - After sunset, some moisture-affected areas may remain warmer than nearby dry areas because of thermal mass and heat transfer differences. - Cloud cover, surface shading, wind and changing temperatures can weaken or alter thermal contrasts. - Environmental conditions leading up to an inspection can affect what appears on the infrared camera, Albert said. - Roofing materials with different thicknesses or compositions can heat and cool at different rates. - Insulation variations, prior repairs, roof penetrations, equipment shadows, surface contamination and membrane color can also create thermal patterns. - HVAC equipment can change roof temperatures for mechanical reasons that have nothing to do with moisture. - Roof sections that receive different amounts of sunlight may show contrasting temperatures even when both areas are dry. - A thermal image is a diagnostic tool, not a definitive moisture test. - When infrared imaging shows a concern, inspectors may confirm the location with moisture meters, electrical impedance testing, core samples or other appropriate procedures. - Core sampling allows direct examination of roofing components but requires careful planning and restoration of the sampled area. - Some roofing assemblies are not suitable for conventional infrared moisture surveys because their construction does not produce reliable thermal contrasts. - Moisture in roofing assemblies can affect insulation, adhesives, roof decks and other components. - Persistent moisture can contribute to corrosion in metal decking or fasteners under the right conditions. - Trapped moisture can also leave underlying deterioration unaddressed if crews apply a coating or add new roofing materials over the problem area. - Commercial roofs often cover thousands of square feet, so infrared imaging can help survey broad areas and document patterns that warrant more investigation. - Thermal patterns can identify isolated problem spots or suggest that suspected moisture extends across multiple roof sections. - Albert said identifying how far moisture may extend can be as important as finding the first area of concern. - Infrared thermography is most useful when combined with a physical roof inspection. - Inspectors may examine seams, flashing, drains, rooftop equipment, penetrations and previous repairs for signs of water intrusion. - Drainage patterns and areas where water regularly accumulates can also provide useful context. - A roof may show thermal anomalies without visible damage, and another roof may have open seams or deteriorated flashing without a clear infrared signal.

Between the lines: - The article frames infrared thermography as a screening tool that narrows where to look next, not as a standalone answer. - The emphasis on weather, roof type and inspection timing shows that interpretation matters as much as the camera itself. - For property owners, the practical value is in deciding whether a roof needs confirmatory testing before moisture turns into a bigger repair bill.

What's next: - Inspectors will typically use infrared findings to guide follow-up testing and build a maintenance or repair plan. - The next step after a thermal anomaly is often confirmation through direct testing or physical opening of selected roof areas. - Jaymar Roofing said the goal is to determine where moisture may be present, what additional testing is needed and which parts of the roofing assembly are affected.

The bottom line: - Temperature differences can point to hidden roof moisture, but they must be interpreted with roof construction, weather conditions and follow-up testing in mind. - Jaymar Roofing, located in Slidell, Louisiana, performs commercial roof inspections, maintenance, repairs and restoration, and evaluates drainage and underlying roofing components. - More information is available on Jaymar Roofing’s social media page.