Rigid Metal vs. Flex Dryer Vent: Which One You Actually Need

Smooth-wall rigid galvanized duct is what code calls for inside walls and through attics or crawlspaces. Lint slides through instead of catching on ribs.

A short semi-rigid metal transition between the back of the dryer and the wall stub is acceptable — but only that short transition piece, kept under 8 feet and never run through walls.

Vinyl, plastic, and foil flex are all documented fire hazards. If you can see any of those behind your dryer, that's the upgrade to do this month.