Commercial Roof Repair
On a low-slope roof, water almost never drips below where it got in. It enters at a seam or a failed penetration, runs along the top of the deck or between insulation boards, and drops through the first joint or fastener hole it reaches — which can be two bays away and one room over. That single fact governs how a commercial repair has to be approached, and it is why chasing the ceiling stain is the most expensive way to fix a roof. APC Roofing does commercial roof repair in Florida, Colorado, Kansas and Missouri.
What actually fails
Seams, first and most often — a lap that was never fully welded, or one that has been worked loose by movement. Then flashings at penetrations: pipes, conduit, and the curbs under rooftop units, where the sheet metal, the sealant and the membrane all have to agree with each other. Then drains, where the clamping ring has loosened or debris has built a dam around it. Punctures from foot traffic and dropped tools. Weathered sealant at terminations and counterflashing. And impact damage from hail or wind-blown debris, which frequently bruises the insulation beneath a membrane that still looks intact from above.
Finding it before fixing it
Locating a leak on a large roof is its own discipline. Infrared or capacitance moisture surveys map where water is held inside the assembly rather than where it is dripping. Core cuts confirm what the survey suggests and show what the roof is actually built of, which is often not what the drawings say. Flood or spray testing isolates a suspect area. None of this is exotic, and all of it beats sealing the nearest visible defect and waiting to see whether the stain returns.
The repair has to match the system
A method that works on a metal roof can be the wrong move on a single-ply membrane. Thermoplastic sheets like TPO and PVC are repaired by heat-welding compatible material; EPDM wants the correct primer and seam tape, since ordinary adhesives will not bond to cured rubber; modified bitumen is patched in kind. Mixing chemistries — a bituminous product against a thermoplastic membrane, for instance — produces a patch that looks right on the day and releases within a year. So the first question on any repair is what the roof is made of, verified rather than assumed.
Wet insulation is not a cosmetic issue
Once water is in the insulation it stays there. It carries weight, it destroys the R-value the building is paying for, and it corrodes a steel deck from above where nobody is looking. Patching a membrane over saturated insulation seals the problem in and lets it spread. The honest scope on a wet roof includes cutting out and replacing the wet material, which is more disruptive and more expensive than a patch, and skipping it is the most common reason a repaired roof leaks again in the same area.
What a repair report should contain
Photographs of each defect with its location on a roof plan. What was repaired and by what method. Any moisture survey results and core cut findings. Conditions observed but not addressed, with a note on how urgent each one is. And the remaining service life the evidence supports, stated as a range rather than a promise. That document is what makes budgeting possible, and it is what an insurer will want if storm damage turns out to be part of the story.
