Is a Range Hood Required by Code In California

When designing your kitchen, it is important to consider building codes regarding ventilation in your home. It can be tempting to assume that if you have a window then you don’t need mechanical ventilation. But, what about during winter when the windows are closed? Or on rainy days? Furthermore more, natural ventilation relies on external air flow, air pressures, etc., and so it is not always the most effective option. That is why, in some instances, there may be state-specific ventilation guidelines that pertain to range hoods in the kitchen area.

Let’s dive a little deeper into the specifics of Californian range hood requirements.

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

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Kitchen Range Hoods Are Not Mandatory According to IRC

While Chapter 15, 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 be still 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:

You prevent oil residue from building up on your walls, floors, ceilings, and furniture.
Your kitchen and adjoining rooms/areas don’t smell like whatever meal you are preparing.
Your home is protected from moisture damage associated with the steam produced during stovetop cooking.
Cooking by-products can be carcinogenous! A range hood helps to limit the amount of by-products you are inhaling.
(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 universal building code, but each country, country, state, or governable area can make amendments to the code 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, such as 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 2019.

map of california drawn in chalk on a blackboard

California Mechanical Code, Section 402.1.2 says that ventilation requirements for single-family dwellings shall be in accordance with Chapter 4 of the California Mechanical Code or ASHRAE 62.2. “ASHRAE” stands for American Society of Heating, Refrigerating and Air-Conditioning Engineers.

ASHRAE 62.2 is a standard that was developed to regulate ventilation requirements for residential buildings that are 3 stories or less, so it is applicable to one- and two-family dwellings but not to apartment complexes. It states that kitchen areas must contain mechanical ventilation to meet residential ventilation requirements.

One of the most effective and easily accessible methods to achieve this mechanical ventilation in a kitchen is through the installation of a range hood. They are specifically designed to handle air containing grease, oil, moisture, and strong odors, which other forms of mechanical ventilation would struggle with.

Required Airflow Rates

California state codes specify how powerful the range hood needs to be to meet ventilation guidelines outlined in ASHRAE 62.2.

According to the most recent version of ASHRAE 62.2, both enclosed and nonenclosed (open-plan) kitchens require a range hood with at least 100 CFM if the ventilation system is going to be run intermittently, i.e., if it is going to be used on-demand only.

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 continuous ventilation systems in enclosed and nonenclosed kitchens, the mechanical ventilation in a kitchen needs to be 5 air changes per hour.

Don’t forget that the size of your kitchen is going to determine how powerful the fan has to be to achieve 5 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.

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. Below are some of the most important rules and regulations to make sure that you are properly and safely venting your kitchen range hood.

Unless otherwise specified, the regulations presented in this section all pertain to the California Mechanical Code 2019.

Range hoods must vent to the outside of the house; you cannot vent it into another room or space, including the attic, soffit, and crawl space (Section 504.1.1).

Backdraft or motorized dampers have to be installed on all range hood exhaust systems to ensure that the exhausted air and cold outside air are not able to enter the kitchen through the range hood and to prevent the build-up of condensation that leads to dripping (Section 504.1.1).

If you are looking for a good recommendation for a backdraft damper, might I suggest AC Infinity dampers? They are effective and long-lasting options for a very reasonable price.

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.
Mounts horizontally or vertically to prevent backflow and debris from entering ducting.
Galvanized steel body with spring-loaded aluminum damper blades that open with minimal airflow.

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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).

The ducting material must be metal and flex ducting cannot be used for venting a range hood (Section 504.3).

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 1000 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.

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.