RoofingSouthwest OhioCincinnati

Oak Hills Roofing Updates 2026

Oak Hills Local School District is putting a new roofing system over the south section of Oak Hills High School in Cincinnati, Ohio. The membrane is 90 mil EPDM rubber, installed with every detail Carlisle requires for a 30-year no dollar limit warranty, with a 40-year membrane manufacturer warranty behind it.

The decision on the page is the thickness. Sixty mil is the default specification on a school roof, and the district went half again heavier. Every foot of perimeter edge metal is replaced with new metal, and the new edge metal is written into the same watertight warranty rather than left sitting outside it — which matters, because the edge is where a rubber roof most often gives up first.

The rest of the roofing scope is the housekeeping that keeps a summer roof job from turning into a fall punch list. Existing ballast is staged in the parking lot and reused rather than hauled off and bought again. Dumpsters and portable toilets are on site for the duration. Grass torn up during the work is brought back to finish grade, seeded and strawed, so the district is not left with the roof fixed and the ground behind the building a mess.

The roof was bought against a pre-bid TOP-C unit price contract the district already holds, on the same agreement it uses for its other maintenance work.

Aerial view over Oak Hills High School's classroom wings and glass-front main entrance

Drone view of a roofing crew installing new black EPDM membrane over a classroom wing at Oak Hills

Aerial view of new black EPDM roofing meeting the older gray roof sections at an Oak Hills school, with material staged on the deck

High drone view of the Oak Hills roof replacement in progress, with the ball field and tree line behind the school

Technical Discussion

Why ninety mil instead of sixty

EPDM is sold by thickness, and thickness is close to the only specification decision a district actually makes on a rubber roof. Sixty mil is the default. It satisfies the warranty requirements, it installs the same way, and on a building nobody walks it will very likely outlast the people who approved it. The case for ninety is not that sixty is a bad membrane. It is about what happens between the day the crew leaves and the end of the warranty.

A rubber roof rarely fails as a sheet. It fails at a puncture: a dropped tool, a screw left behind by another trade, a heel driving a piece of stone through the membrane on a hot afternoon when the rubber is soft. Ninety mil is half again more material to get through, and it is thicker in the places where thickness is doing work — over plates and fasteners, at the edge, and anywhere someone kneels down.

Scale comparison of 60-mil and 90-mil EPDM roof membrane over cover board, each with a pointed object above it, showing the 90-mil sheet is half again thicker against punctures. — Figure 1 — Ninety mil is 50 percent more rubber between a dropped screw and the insulation.

Which is why who walks the roof decides the question. A district with its own maintenance staff has people up there through the year, after storms and at the drains. Those visits are the reason roofs get punctured and also the reason punctures get found before they become deck problems, and a heavier sheet improves the odds on both counts. A building whose roof is visited twice a year by a contractor is carrying a different risk, and sixty mil may well be the right answer for it.

The other half of the choice is weight. A 90-mil sheet weighs roughly half again as much as a 60-mil sheet, on the order of 0.55 pounds per square foot against 0.38, which matters on a roof being recovered rather than torn off, where every pound of new material goes on top of what is already there. Here the old roof came off, so the deck saw no penalty for the heavier sheet, and the district bought the extra rubber for the places its own people kneel.

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