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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.
When designing your kitchen, it is important to consider building codes regarding ventilation in your home. 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.
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.
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.
California Local Codes Require Mechanical Ventilation
Some states, including California, have specific ventilation requirements that homeowners must abide by.
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. It states that kitchen areas must contain mechanical ventilation to meet residential ventilation requirements.
One of the most effective methods to achieve this mechanical ventilation in a kitchen is through the installation of a range hood.
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 kitchens require a range hood with at least 100 CFM if the ventilation system is going to be run intermittently.
Any other kitchen exhaust fan designed for intermittent ventilation will have to have a rating of 300 CFM or one that produces 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 minute.
It should be noted that the kitchen range hood has to be vented to comply with the building code, and flex ducting cannot be used for venting a range hood.
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.
Why Windows Are No Longer Adequate
Residential areas, remodeled homes, and areas greater than 1000 square feet are required to abide by this code, 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.
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