IMC · 2024 International Mechanical Code
§603.4 · Supply duct insulation
Local amendment on §603.4 for the IMC 2024 Minnesota jurisdiction.
Plain-English explainer
The Minnesota amendment to §603.4 keeps the IMC R-6 flexible / R-8 rigid supply-duct R-values. The drafter cites it for permits pulled in the seven-county metro — the local authority's wording matches the IMC without tightening.
Why inspectors flag this
A Minneapolis / St. Paul crew wiring the supply run at the IMC R-6 / R-8 rate passes the Minnesota rough-in; the drafter surfaces the rule so the wrap matches the local amendment.
As quoted in the code: Supply ducts in unconditioned space sized to R-6 (flexible) / R-8 (rigid) for Minnesota duct insulation; return-side insulation remains R-6; the local amendment adopts the IMC base without tightening.
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