Bath Fans and Codes

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Safety

July 15, 2023

Code and Certification Considerations for Bath Fans

Specifying the right bath fan for a new home or remodeling project requires consideration of several factors, including room size, fixture types, desired sound level, and budget. Building codes come into play, of course, but specialty certifications and standards can add another layer of assurance for performance and energy use.

Consider these requirements and guidelines when selecting a bath fan.

Code Requirements for Bathroom Exhaust Fans

Chapter 15 of the International Residential Code (IRC) requires bathrooms and toilet rooms to have a minimum local exhaust capacity of 50 cfm intermittent or 20 cfm continuous. In addition, Section M1505.2 states,

Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or circulated to another dwelling unit and shall be exhausted directly to the outdoors. Exhaust air from bathrooms, toilet rooms, and kitchens shall not discharge into an attic, crawl space, or other areas inside the building.

Bath Fans Certified by the Home Ventilating Institute

It’s important to remember that the building code represents a minimum requirement. For best functionality and efficiency, specifiers should size bathroom fans for each application.

The Home Ventilating Institute (HVI) recommends that exhaust fans for bathrooms up to 100 square feet provide 1 CFM per square foot. For bathrooms over 100 square feet, HVI recommends basing ventilation on the number of fixtures—50 CFM each for the toilet, shower, and tub, or 100 CFM for a jetted tub. This can be accomplished with individual 50-CFM fans over each fixture or one fan equaling the total recommended CFM (e.g., a 150-CFM fan for a bathroom with a toilet, shower, and tub).

Bath fans carrying the HVI-Certified label have undergone independent performance testing, providing buyers with peace of mind that the product’s ratings are not inflated, and the unit will provide proper ventilation as advertised.

Bath Fan Guidelines Under ENERGY STAR®

The ENERGY STAR ^® program provides guidelines and certifications for products that meet specific energy-saving criteria and performance requirements. These standards ensure that the fans effectively remove moisture and odors from the bathroom while minimizing energy consumption.

Key aspects of ENERGY STAR-certified bathroom fans include:

Energy Efficiency

ENERGY STAR-certified bathroom fans use about 50% less energy than standard models. The units’ advanced motor and fan blade technologies deliver adequate ventilation while consuming less energy.

Low Noise Levels

ENERGY STAR-certified bathroom fans are also engineered to run quietly, ensuring a more comfortable and peaceful environment.

Optional Features

Some ENERGY STAR-certified bathroom fans may offer added features such as built-in humidity sensors or occupancy sensors. These features allow the fan to automatically adjust its operation based on moisture levels or occupancy, further enhancing energy efficiency.

Bath Fan Requirements Under California Title 24

California Title 24 — i.e., California’s energy code — is a set of standards designed to reduce energy consumption. As with many areas of the home, Title 24 requirements for ventilation are typically the most stringent in the country. Using Title 24-compliant fans and installation methods, even outside of California, can help ensure optimal performance well beyond code. In many cases, products with Title 24 certification are available throughout the country so manufacturers can ensure compliance within the state.

Under California Title 24, specific requirements for bathroom ventilation aim to promote energy efficiency, indoor air quality, and moisture control. Key points regarding bathroom fans in Title 24 include:

Mandatory Exhaust Fans

Title 24 requires that all bathrooms, including half bathrooms (powder rooms), have mechanical exhaust ventilation. This means that a fan must be installed to remove moisture and odors from the bathroom.

Airflow Rates

Like HVI recommendations, bathroom size determines the minimum airflow rate for exhaust fans. The standards specify a minimum ventilation rate in CFM per square foot of floor area. The rates can vary depending on whether the bathroom has a bathtub, shower, or both.

Controls and Automatic Shutoff

Title 24 mandates that bathroom exhaust fans must be controlled by a switch located inside the bathroom. The switch should be readily accessible to the occupant and easily identified. Additionally, the standards require that the fan has an automatic shutoff feature so that the fan continues operating for a specified period after the switch is turned off to ensure proper ventilation and moisture removal.

Ducting and Venting

The ductwork should be properly sized, insulated (where applicable), and directed to the exterior of the building. The vent termination point should be located away from windows, doors, and other openings to prevent the exhausted air from reentering the building.

Bath Fan Selection Made Easy

Fantech’s bathfan series includes a curated, versatile range of 21 bathroom fan configurations. All 20 residential models in the line meet ENERGY STAR, HVI, and Title 24 requirements. Each fan features energy-efficient, permanently lubricated motors that are designed to increase the life cycle of the units for up to 70,000 hours (about 8 years) of continuous use.

Learn more about the bathfan line here.