The interior finish of walls and ceilings of an atrium must be a minimum of what class?

In commercial building design, particularly in atrium spaces, the requirements for wall and ceiling finishes are established to ensure safety and manage the spread of fire and smoke. The International Building Code (IBC) specifies that the interior finish of walls and ceilings in atriums must be classified according to their fire-resistance attributes.

Class B finishes are commonly required for interior spaces like atriums because they provide a balance between fire safety and aesthetic flexibility. Class B materials have a moderate flame spread rating, which is sufficient for occupancy areas that are designed to be open and accessible to the public. This class is typically appropriate in larger, enclosed spaces where fire safety measures are crucial, and it helps prevent the quick spread of flames or smoke, offering occupants more time for evacuation in the event of a fire.

While Class A finishes have the best performance in terms of flame spread, they may not always be necessary in every type of atrium and can come with higher costs or more stringent application requirements. Class C and Class D finishes, on the other hand, do not provide adequate protection in spaces designed to accommodate large numbers of people, making them unsuitable for an atrium environment. Thus, the minimum class requirement of Class B is in line with safety standards while still accommodating functional