Apprentice answer

Why does aluminum ductwork require closer hanger spacing than galvanized

3rd YearGrease Duct & Specialty ExhaustStop / Verify

Aluminum has a significantly lower modulus of elasticity than galvanized steel, meaning it is much softer and more prone to bending, sagging, and warping under its own weight or internal air pressure. Hanger spacing must typically be reduced from 10 feet down to 4 to 6 feet max for wide aluminum lines.

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Plain-English answer

Field checklist

Stop and verify the approved detail, manufacturer instructions, foreman direction, and project specs before touching it.
Aluminum has a significantly lower modulus of elasticity than galvanized steel, meaning it is much softer and more prone to bending, sagging, and warping under its own weight or...

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Hey boss, I’m on specialty duct and need verification before I touch this: Why does aluminum ductwork require closer hanger spacing than galvanized? Do you want me to stop here and check the approved detail, submittal, or inspector/manufacturer requirement first?

Verify before acting

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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