Makeup air ducts must be constructed according to specific sections if they connect within what distance to a Type I hood?

Makeup air ducts must be constructed according to specific sections when they connect within 18 inches of a Type I hood due to concerns surrounding the performance and safety of kitchen ventilation systems. Type I hoods are typically used to capture and exhaust grease-laden vapors from cooking appliances. To ensure that the air quality within the kitchen remains suitable and to prevent any potential backdraft or contamination, regulations specify the construction criteria for makeup air ducts in close proximity to these hoods.

The 18-inch distance is critical because it reflects the need for a transition area where potential grease accumulation can occur. By adhering to specific construction requirements within this distance, it ensures that the makeup air is introduced in a manner that does not compromise the effectiveness of the hood or the overall air quality. This construction requirement may include proper material specifications, air flow considerations, and additional safeguards against unwanted backflow of air or contaminants, which ultimately help maintain kitchen safety and compliance with the mechanical code.