Clear scope. Clean execution.
Where Commercial Roof Leaks Start in San Antonio
Penetration flashings: Pipe, conduit, electrical, mechanical, and duct penetrations are the highest-probability entry point on San Antonio commercial flat roofs. The pitch pocket and pitch pan flashing systems used on older roofs dry out and crack under San Antonio's extreme UV load - a pitch pocket that was sound at installation becomes a funnel for water infiltration within 10 to 15 years. We inspect every penetration on the roof above a reported leak, not just the visually obvious ones.
Drain and scupper flashings: Primary drains, overflow scuppers, and through-wall scuppers carry the highest water volume on the roof surface. The flashing at the drain bowl-to-membrane connection and at the scupper wall termination are high-stress points that are also high-traffic areas for HVAC maintenance. We lift every drain strainer above a reported leak area and inspect the drain bowl flashing condition.
Parapet base flashings: The base flashing at the parapet wall is the transition from the roof membrane to the vertical surface. Short base flashings - less than 8 inches of vertical height - allow water to wick up the wall and over the flashing termination under wind-driven rain conditions. San Antonio's summer thunderstorms produce 40 to 60 mph wind-driven rain that will find a low parapet flashing.
HVAC curb flashings: San Antonio commercial roofs have dense rooftop mechanical equipment. Each HVAC unit sits on a curb with a flashing that integrates the curb with the roof membrane. Curb flashings that were installed without a heat-welded cap strip, or that have separated at the top bond line, allow water infiltration directly into the building at equipment concentrations - which is often exactly where the ceiling stain appears.
Leak Investigation Methods We Use
Electronic leak detection: For large-format commercial roofs where visual inspection cannot isolate the entry point, we use low-voltage electronic leak detection. The EFVM (electric field vector mapping) method applies a low-voltage field across the wet membrane surface and maps the voltage gradient to locate membrane breaches to within 12 inches. This is the most reliable method for pinpointing entry points on fully adhered or ballasted membrane systems where the water travel path is long.
Infrared thermal scanning: After sundown on a clear day, the roof surface radiates stored heat at different rates over dry and wet insulation areas. Wet insulation retains heat longer and shows as warm zones on a thermal camera scan. IR scanning maps moisture distribution through the insulation layer - not the entry point location, but the moisture pathway from entry point to the building interior. We use IR scanning to scope insulation replacement after the entry point is identified.
Flood testing: On roofs where the entry point is suspected at a specific drain or scupper area, we can temporarily plug the drain and flood the zone to a controlled water depth, then observe the interior from below for active infiltration. Flood testing confirms the entry point location with certainty and is documented with photographs before and after.
Frequently asked questions
I had someone repair a leak on my San Antonio commercial roof three times and it keeps coming back. Why?
This is almost always because the repair was made at the visible symptom rather than the actual entry point. Each repair patched the most obvious candidate and the water found the next path. The only way to stop the cycle is to find the true entry point - which requires a systematic investigation of the roof surface, not a visual scan from the ground or a quick repair at the stain location. If you have had three failed repairs we will tell you what the previous investigations missed.
How long does a leak investigation take?
A standard leak investigation on a commercial flat roof up to 50,000 sq ft takes two to four hours on the roof and produces a written report with photographs within one to two business days. Electronic leak detection or infrared scanning adds time depending on the roof size and conditions. We do not repair first and investigate second - we identify the entry point before any repair work begins.
Can you investigate leaks while the building is occupied?
Yes. Most commercial roof investigations require only roof access - we are working above the occupied space. We coordinate access with the facility manager and typically need a roof access hatch or ladder access point. For buildings without direct roof access we bring our own roof ladder equipment. Tenant disruption during investigation is minimal.
Active leak on a San Antonio commercial building?
We find the entry point - not just the stain - and repair what is actually letting the water in.
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