Insulating Exhaust Ducts In A Commercial Kitchen

We were asked to insulate the kitchen exhaust duct above a commercial kitchen grill at a busy café in a New York City based university.  This request had many layers of difficulty, one of which was when to perform the work.  The café is in operation from  4am to 2am every day or  there was a small window of closure on a holiday weekend.  We had to choose the holiday weekend as we needed the time to get the job done.

IMG_2455Spec’ing in the right fire rated duct wrap insulation was important and required.  Using the wrong type of material could lead to safety issues and is a fire hazard.  One of the requirements of the job was an inspection by the safety coordinator and fire marshal.   

We had in hand the university insulation specification and consulted with the  university engineer and moved forward with 3M’s Fire Barrier Duct Wrap 615.  The technical data for this product can be found here - 3M Fire Barrier Duct Wrap 615 Installation Guide 

As you read the information regarding the install guidance, there are many things to consider.  First, inspect the ducts and locate the duct access doors.  3M’s spec guides you on how to insulate the duct service doors using the same material as the duct wrap.  Keeping the service door accessible is essential for performing regular maintenance, cleaning and inspections.  This will ensure that the fats, oils and grease that accumulate on the surfaces won’t lead to a fire down the road.  Even with the appropriate hood filter, a certain amount of grease will find its way into the duct.  Duct grease fires can be damaging and dangerous.  They travel rapidly throughout the exhaust system while putting adjacent areas of the building at risk.  Burning at 1500F or more can ignite materials outside the duct.   

All horizontal and vertical ducts must be provided with access.  On horizontal ducts, at least one 20in x 20in opening must be provided.   If an opening of that size is not possible, openings large enough to permit a thorough cleaning must be provided at 12 ft. intervals.   

IMG_2456Once you have the design laid out with service doors in mind, you can begin to insulate using the fire rated duct wrap.  Following the project design and 3M technical data, cut outs were made so the service door could be accessed.  We installed the service door kit per the 3M spec and wrapped the duct twice with the fire rated insulation.  The post inspection was performed just in time for any necessary changes.  We were happy to find the job passed inspection and the café was able to open in time for kitchen staff to return after a long holiday weekend.    

If you are faced with an insulation challenge and safety is a concern, please reach out to an insulation expert that will follow code rules, specifications and technical guidance from the manufacturer.

Contact Thermaxx to get help with insulation in your industrial or commercial kitchen.

Suzanne Rowe

Suzanne is a sales manager at Thermaxx in New York City.