Make sure commercial flat roofs meet R30

The current Michigan Commercial Energy Code became effective September 20, 2017 (see this chart for the update history, courtesy of the Building Codes Assistance Project), and this year we've heard scattered reports across the state that building inspectors are mandating compliance to the R30 requirement for commercial flat roofs.

1803-ISOtwolayers.jpgTraditionally, low slope contractors could use two layers of 2.5" ISO to achieve acceptable levels of insulation. But 2.5" ISO is rated at R14.4, for R28.8 at two layers. We've seen customers forced by inspectors to revise their projects to meet R30. This can be done by using two layers of 2.6" ISO (R15) to achieve the R30 required by the energy code.  Best play it safe and spec 2.6" ISO for your upcoming projects!  Inspectors are taking notice in 2018.

For a breakdown of R values by ISO size, consult this handy chart from Hunter Panels.

Wimsatt stocks ISO panels in a variety of sizes, including 2.6" R15.

Tags Energy Code ISO Commercial Roofing R-Value

About Dave Karras

Dave Karras

Dave Karras is the Marketing Manager at Wimsatt Building Materials.

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