TinnerFlow logoTinnerFlow™
Apprentice Q&A · #070

How do I keep my flex duct cuts clean without tearing the inner core?

2nd YearFlex Duct & GrillesYELLOW · Check First

Use a dedicated dual-blade insulation knife to slice cleanly through the outer vinyl jacket and the fiberglass insulation core down to the wire ribbing. * Use heavy-duty wire side-cutters (dikes) to snap the internal coiled spring steel wire cleanly. Never try to cut the spring wire using your aviation metal snips, or you will ruin the snip blades instantly.

Search Field RescueOpen in Q&A search

Plain-English answer

Use a dedicated dual-blade insulation knife to slice cleanly through the outer vinyl jacket and the fiberglass insulation core down to the wire ribbing. * Use heavy-duty wire side-cutters (dikes) to snap the internal coiled spring steel wire cleanly. Never try to cut the spring wire using your aviation metal snips, or you will ruin the snip blades instantly.

--

Field checklist

Ask Foreman

Hey boss, I’m checking flex duct & grilles: How do I keep my flex duct cuts clean without tearing the inner core? I found the likely issue and want to verify the next step before I lock it in. Do you want me to adjust it now or check the drawing/detail first?

Open Ask Foreman

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.

Related questions

Related Field Rescue routes

Related mistakes & recovery checks