Bowling Alley Kitchen: DuraSystems KEX Grease Duct

The Challenge

The tenant build-out for a new bowling alley inside an existing San Jose mall placed the commercial kitchen more than 120 ft from the nearest fire-rated shaft. California Mechanical Code requires grease duct to slope ¼” per ft for runs under 75 ft of horizontal distance, and 1” per ft for runs over 75 ft. At this length, code-compliant slope would have dropped the duct more than 120”, over 10 feet, across the run, which was incompatible with the finished ceiling elevations the architect needed to hold throughout the space.

The Solution

We brought DuraSystems’ factory-built grease duct to the design team. The DuraDuct KEX system is a UL/ETL-listed, 2-hour fire-rated, double-wall (3” insulated) grease duct that has been tested to support a ‘seesaw’ routing method: instead of a single continuous slope, the run uses multiple low points along its length, each equipped with a drainable reservoir / cleanout. Grease collects at those low points and is removed during scheduled cleaning, satisfying the intent of the slope requirement without the elevation drop. With KEX specified, the engineer redesigned the kitchen exhaust run to hold ceiling height across the 120′+ path to the fire-rated shaft.

The Result

The bowling alley kept its designed finished ceiling elevations across the full kitchen exhaust route. The double-wall 2-hour fire-rated assembly satisfied code through the existing mall structure, and the drainable seesaw routing gives the operator a maintainable, cleanable grease duct without the +10′ slope drop a site-built duct would have required.