ICC Commercial Mechanical Practice Exam

What material must ducts penetrating a wall into a garage be made of?

1. Plastic

2. Sheet steel

3. Wood

4. None of these

The correct answer is: Sheet steel

Ducts that penetrate a wall into a garage must be constructed of sheet steel due to safety and fire protection standards. This requirement is put in place to minimize risks associated with fire and to prevent the ignition of any flammable materials that may be present in the garage environment. Sheet metal ducts are robust and can withstand higher temperatures compared to plastic, which may warp or melt, posing a significant hazard. Similarly, wood is not suitable for this application due to its flammability and susceptibility to damage from moisture and pests. Thus, the use of sheet steel is a crucial safety consideration in building and mechanical codes, ensuring that the ducts provide a safe means of ventilation or air distribution without increasing fire risks in attached structures such as garages.