How do I seal a duct penetration going through a non-rated CMU wall?

Pack the open annular space surrounding the duct tightly with mineral wool insulation backing material to fill the structural void. Apply a thick, continuous smooth bead of standard construction polyurethane caulking or mastic sealer around both sides of the wall line to create an airtight and dust-tight perimeter wrap.

['Pack the open annular space surrounding the duct tightly with mineral wool insulation backing material to fill the structural void. Apply a thick, continuous smooth bead of standard construction polyurethane caulking or mastic sealer around both sides of the wall line to create an airtight and dust-tight perimeter wrap.']

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Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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Pack the open annular space surrounding the duct tightly with mineral wool insulation backing material to fill the structural void. Apply a thick, continuous smooth bead of standard...

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how do i seal a duct penetration going through a non-rated cmu wall?

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