How to Seal the Duct Work on a Kitchen Vent


The exhaust of grease cooking fumes, steam, and aromas via the kitchen venting system should normally be sent all the way to the outside of the house in accordance with best standards. The ductwork that transports exhaust either travels from the attic to the roof or through the wall voids to an outside vent. In order to avoid potentially hazardous gases from cooking from condensing in enclosed areas like the attic or the walls, the vent ducts in the kitchen need to be effectively sealed against leaking. It is possible that air pulled straight from the cooktop will be hot, full of moisture, and a challenge to the procedures used for duct sealing. The following is an example of a standard duct installation and sealing.

  1. For the ducts in the kitchen, use steel ducting that has been authorised by Underwriters Laboratories, or UL. It is important that the inside of the ductwork be smooth and devoid of any corrugated ridges, since these tend to collect grease residue and are difficult to clean.

  2. According to Family Handyman, you should run the ducting along the path that is the quickest and most direct way to get to the outdoor vent. Check to see that there are no impediments in the route, such as plumbing vents, electrical conduits, or ceiling joists, and then proceed. It is recommended that you consult the owner’s handbook of the fan in order to determine the maximum length of ductwork that is compatible with the fan’s capacity.

  3. According to the recommendations of the Office of Energy Efficiency and Renewable Energy, mastic sealant should be applied to joint surfaces before joining spans of ductwork. The mastic may be spread on by hand or painted on with a paintbrush and applied in generous amounts onto the ducting. When applying mastic, it is important to protect your hands by donning a pair of thick cotton gloves. This is because the edges of metal ducts may be jagged, and pointy screw points may protrude. !!-!! First, join the individual segments of the duct, and then use sheet metal screws measuring 1/4 inch to mechanically secure each connection.

  4. Using duct sealing tape that has been authorised by the UL and has an aluminium foil backing, wrap the exterior of the joint seams. This tape has been evaluated for use in environments with high temperatures and high levels of humidity.

  5. Wrap the outside of the joint seams with UL-approved 181A aluminum foil-backed duct sealing tape. This tape is tested for applications that present high temperatures and humidity.

    Things You Will Need

    • 1/4-inch sheet metal screws

    • Screwdriver

    • Mastic duct sealing compound

    • Paintbrush

    • UL-approved 181A aluminum foil-backed duct tape