Roof Leak Repair

Finding where a commercial flat roof is leaking is harder than finding where it is wet inside the building. Water travels horizontally through insulation before entering the building below - the interior leak point and the roof failure point are rarely in the same location. We find the source.

The most common call we receive from Atlanta commercial building operators is some version of: the ceiling is wet, the contractor came out and patched the area above it, and it is still leaking. The patch did not work because the patch was placed above the interior leak point, not above the roof failure point. On a commercial flat roof, water enters the membrane at a failure point, travels horizontally through the insulation, and enters the building below at a low point in the deck - which may be 10 to 30 feet from the actual membrane failure. Patching above the wet ceiling is patching the wrong location.

Locating the actual source of a commercial roof leak requires a systematic approach: infrared or nuclear moisture scanning to identify saturated insulation zones, visual inspection of the membrane above high-probability leak sources - drains, penetrations, seams, flashings, parapet terminations - and correlation of those findings with the interior leak pattern. We work through that process methodically and document what we find before applying any repair material.

Atlanta's 53-inch annual rainfall makes active leak sources easy to distinguish from historic moisture intrusion - the building will tell you within a few weeks whether the repair is holding. But confirming the repair holds means knowing what was actually repaired, where, and with what material. Our repair reports document all of this.

Water on a commercial flat roof follows the path of least resistance through the membrane and insulation assembly. When the membrane fails at a seam or penetration, water enters the membrane at that point and travels downhill through the insulation - which has essentially no drainage capacity - until it finds a gap in the vapor barrier or deck to pass through. The interior ceiling stain appears at the deck's lowest point, which may be feet or dozens of feet from the membrane failure point.

Atlanta's high-humidity environment compounds this. Insulation in Atlanta commercial roofs often carries some background moisture from condensation cycling that has nothing to do with active membrane failure. When a new leak develops, the interior moisture pattern reflects both the active infiltration and the existing wet areas - making the leak source even harder to locate by looking at the ceiling from below.

The tools that work for commercial flat roof leak location are infrared thermographic scanning - which images temperature differential between wet and dry insulation - and nuclear moisture meter scanning, which directly measures moisture content in the insulation. We use both depending on the building's situation. Infrared requires a temperature differential of at least 15 degrees between the roof surface and the ambient - a condition Atlanta reliably provides during morning hours after overnight cooling, when the wet insulation retains heat longer than dry areas. Nuclear scanning works day and night regardless of temperature but requires access to the roof surface across the full area.