The architect just called, and the owner wants to add a residential oven/range to their breakroom. Do I need a commercial hood? This could be expensive, but I don’t want to discourage my client. Can you help?

As a consulting MEP engineer, this type of issue will likely come up in around 75% of your projects. While your instinct may be to dive straight into the International Mechanical Code (IMC) to find the answer, what you’ll quickly discover is that the code is filled with regulations for residential equipment in residential settings, and commercial equipment in commercial settings. But when it comes to residential-grade equipment in a commercial environment, there’s a notable gap, leaving you with the daunting question: “What should I do now?”

The reality is, you’re entering a grey area. The code, in its strictest interpretation, states that if grease-laden vapors are produced, a Type I hood is required – end of story. However, the code commentary notes that it’s not the intention of the code to impose unnecessary and costly restrictions on the public. In this scenario, your ability to balance knowledge of the code with practical wisdom in its application will define your reputation with the architect and owner. The truth is, code compliance is not always black and white.

Experience will teach you that addressing such issues requires a practical approach and a thorough analysis of the situation. This isn’t about following strict formulas – it’s about applying your understanding to each unique application. To guide the architect and owner to the best solution, you need to ask the right questions.

Key Questions to Ask:

How will the breakroom be used (Application)? Is it a demonstration kitchen, a space for lunch breaks, client entertaining, or just a warming kitchen with no grease-laden vapor production?
Will any food products be sold for public consumption? If the answer is yes, this is a commercial kitchen, period.
What equipment will be in the “non-commercial” kitchen? Oven/range, microwave, coffee maker, dishwasher, refrigerator, etc. Are all of these items residential-grade?
What is the facility type (occupancy classification)? Is it an office, school, hospital, warehouse, or another type of building?
How often will the kitchen be used? How many meals will be warmed or prepared each day?
What type of food will be prepared, and how? Are you simply warming pre-cooked meals, steaming vegetables, brewing tea? Or are you preparing large quantities of bacon every morning? The type of food determines the types of vapors created, which is directly addressed by the code. Are you generating grease-laden vapors?
What fire protection measures are in place? Is the building fully sprinklered? Does the existing hood have a dedicated fire-suppression system? Have you considered adding one?

Once you’ve gathered answers to these questions, the picture will start to come together. For instance, let’s say the breakroom is in an office building, used infrequently, and designed for warming purposes only. In this case, a residential hood could suffice, and no Type I or Type II hoods would be necessary. Plus, the owner has agreed to avoid activities like frying bacon in the breakroom. We’re good to go, right? Not so fast.

We’re still in that grey zone. This means that even with the answers in hand, you must document your analysis in a letter. The owner will need to sign off on the usage conditions, and you’ll also need to seek approval from the Authority Having Jurisdiction (AHJ) for an exception to the code.

Ultimately, there are situations where exceptions to the Type I and/or Type II hood requirements can be justified. Be prepared for a case-by-case evaluation, as well as additional requirements from the AHJ. In some instances, the AHJ may approve the use of a residential hood, provided a point-of-use automatic fire suppression system is added.

With careful analysis, proper documentation, and collaboration with the AHJ, you can navigate this grey area successfully.

Written by By Jonathan Moore, Mechanical Engineer