OHio Multifamily R20 insulation requirement for new roofs

[DL Martin]

Greeting;

Today, while gathering information for obtaining a bid on 7,200 sq ft of flat roof for a 38 unit apartment complex, I was told that in Cincinnati, Hamilton County, if a permit is pulled for a re-roof, prior to issuing the permit, the building department must inspect and verify that R20 insulation is in the rafters. 

No R20, no re-roof permit. 

How long has this requirement been in place?

DL

@Ben Leybovich this  (insulation) looks to be (approximately) another $12,000 capex every 12 to 15 years (flat commercial roof) in addition to the roof itself. (Assuming that they put rigid insulation boards down under the rubber roof, as opposed to taking down the ceiling of all of the upstairs apartments, installing R20 insulation between the ceiling joists, and then reinstalling drywall, texture and paint. Ben, I've never seen this discussed on BP. Is this an Ohio "green" statute or is this just a "Hamilton County" requirement?