Which percentage slope is required for ducts serving a hood?

Which percentage slope is required for ducts serving a hood?

• A. 4%
• B. 3%
• C. 5%
• D. 2%

Answer: (D)

Ducts serving a kitchen hood must have a slight downward slope so condensate and grease that collect in the duct can drain away by gravity instead of pooling and causing buildup. This drainage reduces corrosion, minimizes grease accumulation, lowers fire risk, and makes inspection and cleaning easier. A two percent slope (about a quarter inch per foot) provides enough fall for horizontal runs to drain reliably without adding unnecessary height or complicating installation. Slopes steeper than this aren’t required and can add cost, while flatter slopes may not drain effectively. So, two percent is the standard slope for hood ducts.

Ducts serving a kitchen hood must have a slight downward slope so condensate and grease that collect in the duct can drain away by gravity instead of pooling and causing buildup. This drainage reduces corrosion, minimizes grease accumulation, lowers fire risk, and makes inspection and cleaning easier. A two percent slope (about a quarter inch per foot) provides enough fall for horizontal runs to drain reliably without adding unnecessary height or complicating installation. Slopes steeper than this aren’t required and can add cost, while flatter slopes may not drain effectively. So, two percent is the standard slope for hood ducts.