Commercial Roof Inspection Checklist

Surface and drainage

Start where the water tells you the most.

Ponding — water still sitting on the roof 48 hours after rain — is not a cosmetic issue. It degrades the membrane, adds structural weight, and exposes every seam in the puddle to constant moisture. Note the location and size. If ponding areas are growing or new ones are showing up, the structure underneath may be deflecting.

Check every drain, scupper, and gutter. Clear the strainer baskets. If a drain seems slow, the blockage may be below the surface, not just debris on top.

Walk the surface. Look for blistering, cracking, splitting, erosion, or spots where the membrane looks stretched or thin. On modified bitumen or built-up roofs, alligatoring — a web of cracks that looks like reptile skin — means the surface has lost its flexibility.

Run your finger along accessible seams on single-ply systems. Anything that feels loose, lifted, or separated gets noted. Pay extra attention near rooftop equipment, at direction changes, and at T-joints where three panels meet.

Check the edges — drip edges, gravel stops, coping, parapet caps. These protect the most wind-vulnerable parts of the roof and are usually the first to show storm damage.

Penetrations and problem zones

Most commercial roof leaks don't start in the middle of an open membrane. They start where something goes through it or connects to it.

Check every penetration — pipes, conduits, HVAC curbs, exhaust vents, electrical masts. The flashing around each one should be intact, well-adhered, and free of cracks or gaps. Sealant that's shrunk, cracked, or pulled away needs attention before it becomes a leak.

HVAC equipment gets special focus. The curbs underneath rooftop units are high-traffic zones — technicians walk around them, lean tools on them, and occasionally damage the flashing without realizing it. Check all four sides of every curb. Check whether equipment is sitting on proper supports or directly on the membrane, which causes damage over time.

Look at previous repair areas. Patches have edges, and edges are failure points. If an old patch is lifting or showing new distress, the original problem may be coming back — or the repair didn't address the real cause.

Anywhere the roof changes elevation, material, or direction is a transition zone. Transitions are inherently complex and leak-prone. They deserve more scrutiny than the open field.

Interior and documentation

The roof tells half the story. The inside of the building tells the other half.

Check the spaces below the roof for staining, active drips, musty smells, or mold. If there's a drop ceiling, lift tiles in areas that have had past problems and look at the deck above. Sometimes the biggest clues are hiding above the grid.

Ask the people who work in the building. A tenant mentioning condensation or a musty closet might be describing a roof leak that hasn't produced a visible drip yet.

Pull the last two to three years of repair invoices and maintenance records. Plot the repair locations on a simple roof diagram. A cluster of work in one area, a line of failures along a seam, recurring problems near one piece of equipment — these patterns are invisible in a stack of invoices but obvious on a map.

Photograph everything during the inspection — problems and areas in good condition. Date each photo. This creates a baseline for the next inspection, which is the only way to objectively measure how fast things are changing.

Organize the findings: what needs attention now, what should be addressed within six months, and what to monitor. That format gives ownership something they can act on.

If your findings raise concerns, request a professional assessment. We document commercial inspections with photos and deliver prioritized recommendations you can act on.