Unsightly, perhaps. Necessary, 100%

Restaurant kitchen exhaust fans not only remove the potentially odorous and toxic products of combustion that are unavoidably created through the cooking process, but they are also crucial to saving lives in the event of fire by helping to remove flames and smoke from the space. 

Therefore, if any part of the kitchen exhaust fan, grease duct, or hood are not installed as per the NFPA-96 Standard for Ventilation Control and Fire Protection, it puts the public—and your employees—at risk.

The Importance of Proper Kitchen Exhaust Fan Installation

Case Study #1

A field review on a Vancouver restaurant where the installing contractor approved sheet metal screws and fire stopping in lieu of proper welding or an industry standard fastening method, revealed that it’s important to understand that proper installation is as important as the actual fan.

kitchen exhaust fan case study #1

It might look secure and be deemed usable at first glance. However, upon closer examination, this method was not up to standards.



remove screws in grease duct

According to NFPA – 96 Section 8.1.4., Sentence 4:

The fan shall be connected to the exhaust duct by flanges securely bolted as shown in Figure through Figure or by a system specifically listed for such use.

Kitchen Exhaust Fan Installation Process

Case Study #2

During another restaurant inspection, we found the contractor had connected a flexible duct between the grease duct and the kitchen exhaust fan, rather than taking the time to measure and weld the two together directly.

In standard HVAC systems, this is okay because the system isolates the vibration and noise. However, in a commercial kitchen, this would likely fail in the event of fire and allow smoke build-up.

flexible connections are not allowed in kitchen exhaust systems

As per NFPA – 96 section  8.1.4. Sentence 5:

Flexible connectors shall not be used.

Kitchen Exhaust Fan Connection to Roof

Case Study #3

In this picture we have 3 issues:

1.  The kitchen exhaust fan has been bolted to a combustible wood curb and not metal curb.
2.  The kitchen exhaust fan is closer than 18” to the combustible roof structure.
3.  The fan curbs themselves are not connected to the roof thus not structurally sound.
If you look a little closer you will see the 18” tall metal curbs behind the kitchen exhaust fan that the contractor decided to abandon!

Improper Kitchen Exhaust Termination 

Case Study #4

Another restaurant, another problem. In this case, the mechanical engineer signed off on an installation that leaves the exhaust vent inside the space! This duct is connected to a Class 2 hood and the cooking appliances are electric. 

Forget citing the code that states how many things are wrong with this scenario, it’s basic common sense that the exhaust needs to escape to the outdoors, not within the space.

exhaust systems need to lead outside

Do Your Due Diligence When Hiring a Contractor and Engineer

When hiring an engineer and contractor, ask for resumes, previous client work, and even references. Research the restaurants they have designed for and fact-check! Cross-reference the mechanical engineer on EGBC to see if they have been reported for any misconducts, or —even worse—if they’ve ever been suspended.

If you have any questions about the mechanical, plumbing or hood fire suppression for your restaurant, give us a call! We always have time to discuss the details.