A flexible dryer duct is considered a "transition duct" by the building code, meaning it is only supposed to be used as a transition connection between the dryer and the smooth metal dryer duct that runs to the duct termination at an outside wall or the roof. The transition duct cannot be longer than 8-feet long. 

    Also, only one section of transition duct is allowed to be used and it cannot pass through a wall or other object that obscures any part of it. So the example shown above is not acceptable. But, of course, if it is possible to run one length of transition duct from the dryer to duct termination without concealing any part of it, that is acceptable.

    To learn more, go to our articles How do you inspect a dryer vent? and What is the maximum length for a clothes dryer vent? and Why is it bad to have a clothes dryer vent near an air conditioning condenser (outdoor unit)? and What are the code requirements for an outdoor dryer vent cover? 

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