Dryer exhaust ducts shall not be joined with screws that protrude more than ________ inch into the inside of the duct.

In the context of dryer exhaust duct installation, it is essential to minimize any obstructions within the duct that could restrict airflow or create turbulence in the exhaust system. The specific requirement stating that screws used to join duct sections should not protrude more than 1/8 inch into the inside of the duct is designed to prevent any potential blockages that could lead to lint buildup, reduced exhaust efficiency, or even fire hazards.

Screws that protrude too far into the duct can create an uneven surface, making it difficult for lint and other debris to be carried away efficiently. This can significantly impair the performance of the dryer and could lead to safety issues. Thus, keeping the screw protrusion to 1/8 inch or less ensures that the airflow remains unobstructed, promoting better exhaust flow and reducing the risk of lint accumulation, which is a critical factor in maintaining dryer efficiency and safety.