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Is a Range Hood Required by Code In California

Range hoods do a lot to protect the indoor air quality of your home and, to a certain extent, the facade and structural elements. They provide ventilation without having to rely on open windows, which is annoying in cold, rainy, or windy weather.

Things like home exhaust ventilation are regulated by building codes because of their beneficial impact on a home. However, there is a difference between being regulated by the code and being required by it. So, let’s look at both of these things as they pertain to California.

Although range hoods aren’t mandatory according to the IRC, California code requires mechanical kitchen ventilation that exhausts 100-300 CFM (intermittent ventilation) or allows 5 air changes per hour (continuous ventilation). Range hoods are a good way to meet this requisite mechanical ventilation.

Kitchen Range Hoods Not Mandatory According to IRC

While Section M1503 of the International Residential Code (IRC) contains regulations regarding ventilation in the kitchen as well as the design and installation of range hoods, it does not actually require range hoods to be installed in kitchens.

Adequate ventilation can be provided by a window that opens to the outside, for example.

Even though the range hoods are not mandatory according to IRC, they should still be used, regardless of where your home is.

Here are 5 reasons why it’s important to have a range hood, even though it’s not required by code:

  1. You prevent oil residue from building up on your walls, floors, ceilings, and furniture.
  2. Your kitchen and adjoining rooms/areas don’t smell like whatever meal you are preparing.
  3. Your home is protected from moisture damage associated with the steam produced during stovetop cooking.
  4. Cooking by-products can be carcinogenous! A range hood helps to limit the amount of by-products you are inhaling.
  5. (If range hoods are a local code requirement) Your kitchen is code-compliant, which makes it legal (there is such a thing as an illegal kitchen), saleable, insurable, and safe.

California Local Codes Require Mechanical Ventilation

The IRC is used as a baseline building code for US states and territories, but each county, state, or governable area can make amendments to the code to make it applicable to their specific area, and these altered regulations take precedence over those in the IRC.

The reason these local codes differ and take precedence is that not all states, counties, provinces, etc., are subject to the same factors, like weather conditions, building designs, and atmospheric pollution.

In California’s case, they have not included in their residential code any of the regulations set out in the mechanical sections of the IRC.

Instead, they have created their own set of regulations on mechanical ventilation in the home (including the kitchen).

These regulations are presented in California Mechanical Code 2022. Significant changes to the setup of the code were made since the 2019 version. However, the basic information remains the same. Previously, the code referred to ASHRAE standards. The 2022 version does not.

map of california drawn in chalk on a blackboard

California Mechanical Code, Section 405.4 says that the kitchen has to be provided with mechanical ventilation leading to the outside.

It implies that the ventilation system must have a fan-based design but it can run on-demand or continuously, and it can be manually or automatically controlled.

So, while mechanical ventilation is required, this does not have to take the form of a range hood.

That being said, a range hood does present one of the most effective and easily accessible methods to achieve this mechanical ventilation in a kitchen.

Required Exhaust Rates

Section 405.4.1 goes on to specify how powerful the chosen method needs to be to meet the ventilation requirement.

An exhaust rate of at least 300 CFM is required for intermittent ventilation options unless you use a range hood.

With a range hood, you need an exhaust rate of at least 100 CFM. This give you an indication of how much more effective range hoods are considered to be at achieving proper kitchen ventilation.

If you have a continuous ventilation system, it needs to enact five air changes per hour.

Any other kitchen exhaust fan designed for intermittent ventilation will have to have a rating of 300 CFM or must be capable of achieving five air exchanges within one hour for enclosed kitchens.

Faber LEVA36SS300-B 36" 300 CFM Levante I Under Cabinet Range Hood, Stainless Steel

Don’t forget that the size of your kitchen is going to determine how powerful the fan has to be to achieve five air changes each hour. Obviously, the larger your kitchen, the more air volume has to be exchanged.

Furthermore, these are the minimum airflow ratings.

If you are someone who, by choice, necessity, or as part of your home business, spends many hours each day cooking in the kitchen, then you may benefit from a stronger exhaust system.

You will, however, have to balance this with the cost of a stronger range hood and the power used to run it. You may also have to take into consideration make-up air.

Sound Limits for Kitchen Range Hoods

Not only are the airflow rates regulated, but the sound levels of kitchen range hoods are also controlled by the local state codes.

Range hoods used intermittently cannot exceed a noise level of 3 sones, and for those used continuously, the level cannot exceed 1 sone.

Important Venting and Ducting Regulations

It should be noted that the kitchen range hood has to be vented to comply with the mechanical code, i.e., it cannot be ductless, and this venting has to lead to the outside.

Below are some of the rules and regulations that were previously included in the California Mechanical Code.

I cannot find them specified for kitchen ventilation in the latest version. However, they are still important and should be followed to ensure the best use of your range hood.

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AC Infinity 6" Backdraft Damper, One-Way Airflow Ducting Insert with Spring-Loaded Folding Blades for 6” Ducting in Range Hoods and Bathrooms Fans
  • An antidraft duct insert designed for use with range hoods, bathroom fans and other home HVAC applications.
  • Features outer rubber gaskets that create an airtight seal and grip between the damper and ducts.
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  • You cannot link a range hood’s exhaust system to another exhaust system such as the dryer or bathroom fan (Section 504.2).
  • Ducts must be insulated if the air passing through them exceeds 140 °F (60 °C) (Section 1604.1).

Why Windows Are No Longer Adequate

Residential areas, remodeled homes, and areas greater than 1,000 square feet are required to abide by the mechanical code of California, and opening windows do not satisfy this ventilation requirement under California State Laws.

minimalist kitchen with a closed window

In the past, opening windows satisfied California’s residential ventilation requirements.

However, studies found that citizens of California did not open their windows frequently enough to provide proper in-home ventilation or keep indoor pollutants at an acceptable level. This lack of proper ventilation is why the state code now requires range hoods in the kitchen area.


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