Commercial Roof Moisture Surveying
You’ve walked the roof. You’ve had a contractor look at it. You’ve patched the spots that looked suspicious. And the leak is still there.
This is one of the most common, and most frustrating, scenarios in commercial roofing. The roof surface appears intact. There’s no obvious crack, no open seam, no failed flashing you can point to. But just below you, water is getting in and traveling through the roof assembly before it shows up somewhere you can see it.
There’s a specific reason this happens, and a specific way to find the source.
Why Water Sometimes Appears Far From Where It Enters
Commercial roofing systems are built in horizontal layers: membrane on top, insulation in the middle, deck underneath. When water infiltrates through even a tiny breach in the membrane (a pinhole in a seam, a compromised fastener, a hairline crack near a drain), it doesn’t drop straight down. Instead, it often runs laterally along the top of the insulation, following the natural slope of the roof system, until it finds a pathway through to the next layer.
By the time that water appears as a ceiling stain, a drip, or damp insulation in the wall cavity, it may have traveled 10, 20, or more feet from its actual entry point. Patching based on where the leak appears is guesswork. The entry point could be anywhere upstream.
Why Visual Inspection Alone Can’t Always Find It
Even an experienced roofer walking the surface of a commercial roof can miss the entry point when:
- The breach is in a seam that visually looks sealed but has delaminated below the surface
- The damage is at a flashing junction or penetration where small gaps aren’t obvious without probing
- The membrane has micro-cracks that are invisible to the naked eye, but allow water infiltration under hydrostatic pressure
- Multiple small breaches exist across the roof, with moisture saturating a large area rather than draining from a single point
In these cases, the only way to quickly and accurately locate the problem is with tools and methodology that can detect moisture beneath the surface and map where it is throughout the system.
What a Moisture Survey Does Differently
The aerial view.
Conducted via drone after civil sunset, thermal imaging detects the temperature difference between wet and dry insulation. Wet areas retain heat longer, showing up in thermal imaging. This gives us a map of the entire roof from which to start our investigation.
Verifying Results
Once thermal scanning identifies anomalies, a small probe is inserted directly into the roof assembly at each flagged location to measure and quantify moisture content. Our inspectors use a Tramex RWS impedance scanner to pinpoint the optimal probing location within each anomaly, ensuring the most accurate reading possible. This is the step that turns observed anomalies into documented, defensible data our clients can take to contractors, insurers, and manufacturers.
Moisture Mapping
As an optional service, many clients prefer to add to our moisture surveys. This step of the process utilizes our impedance equipment, such as the Tramex DecScanner to scan the roof’s surface entirely, measuring the electrical resistance of the materials below the surface. Moisture conducts electricity well and garners different readings than a dry area of the roof would. Once this equipment has been calibrated to the roof system we are working on, it allows us to identify and outline areas that have tested as wet so that we know where the problem areas are with a low margin for error, even if these areas look just like any other.
What the Report Tells You
After our inspectors have completed their inspection and final payment has been received, you will receive a comprehensive report outlining all of the findings from our investigation. This report can include:
This report is the foundation for an accurate scope of repair or restoration. It eliminates the guesswork and breaks the cycle of patching one spot while the real problem remains elsewhere.