Recommended Specifications: Dryer exhaust ducts should be constructed of 4 inch, rigid metal pipe with a smooth interior and joints running in the direction of air flow. The flexible foil and vinyl types are considered to be a fire hazard. The dryer duct should be as short and straight as possible. The maximum length for a dryer duct is 25 feet; however, it must be reduced by 2.5 feet for each 45 degree turn and 5 feet for each 90 degree turn because bends restrict air flow.

Dryer Vent Cleaning Davis Gives Homeowners Tips On Dryer Vent Installations