What is the primary function of a smoke shelf in construction?

The primary function of a smoke shelf in construction is to prevent downdrafts. Smoke shelves are architectural features found in flue systems of chimneys or ventilation shafts. They are specifically designed to create a barrier that catches smoke and directs it upwards while preventing cold air from entering the system. This design is crucial during a fire, as it helps to ensure that smoke rises and escapes through the chimney rather than back down into the living space, thereby enhancing safety and air quality.

In this context, the smoke shelf plays an essential role in maintaining proper airflow and smoke evacuation during a fire, which is critical for both building safety and compliance with fire codes. The effectiveness of the smoke shelf in preventing downdrafts contributes significantly to the overall performance of the chimney system.