What Is a Type 1 Commercial Range Hood? (CFM Specs)
A Type I commercial range hood is a listed exhaust hood designed to capture grease-laden vapors from cooking equipment and carry them outdoors. Its required airflow, measured in cubic feet per minute (CFM), depends on appliance duty, hood shape, and the locally adopted code. There is no single CFM-per-foot value that fits every kitchen or installation.
Would you rather size a hood from a number printed online, then discover it cannot capture the cooking plume, or match it to the appliances, hood listing, and code from the start? The second approach is more reliable. Below, I explain how Type I hoods work, how to use common CFM tables, and what to check before installation.
What is a Type I commercial range hood?
A Type I hood captures and exhausts grease-laden vapors produced by cooking. It is used over appliances that generate those vapors, such as fryers, griddles, and many ranges. The hood is one part of a system that also includes filters, ductwork, an exhaust fan, and fire protection.
“Range hood” can suggest a simple fan above a stove. A commercial Type I system is more specific: its hood must be listed for the intended use, and its exhaust rate and installation must meet applicable code and manufacturer requirements. The authority having jurisdiction (AHJ), usually the local building or fire official, determines which rules apply.
Type I versus Type II hoods
Type I hoods are for grease-laden vapors. Type II hoods are generally for heat, steam, or odors when cooking does not produce grease-laden vapors. The appliance and cooking process determine the hood type; the label “range” alone is not enough to decide.
For example, a fryer normally needs a Type I hood. A dishwasher that releases heat and steam may be served by a Type II hood, subject to the applicable code. When a cooking line includes different appliances, have the hood designer or local official confirm which equipment must be under the Type I hood.
Type I hood CFM specs and how to size airflow
CFM means cubic feet per minute, the volume of air a fan moves in one minute. Model-code tables commonly set minimum exhaust rates per linear foot of hood, with different rates for appliance duty and hood configuration. These values are references, not a universal specification for every project.
The table below gives common IMC model-code reference rates. Confirm the adopted code edition, the exact table and hood configuration, and any local amendments. The hood’s listing and manufacturer’s performance data may also affect the required rate.
| Hood configuration | Light duty | Medium duty | Heavy duty | Extra-heavy duty |
|---|---|---|---|---|
| Wall canopy | 200 CFM/ft | 300 CFM/ft | 400 CFM/ft | 550 CFM/ft |
| Single island | 250 CFM/ft | 400 CFM/ft | 500 CFM/ft | 700 CFM/ft |
How to calculate a table-based exhaust rate
Multiply the applicable rate in CFM per linear foot by the hood’s length in feet. First identify the appliance duty and hood configuration. Then check the adopted code and hood documentation. The result is a planning reference, not a replacement for a complete design or code review.
For a 10-foot wall-canopy hood classified for heavy-duty appliances, the table-based calculation is:
10 ft × 400 CFM/ft = 4,000 CFM
That result does not prove the system will capture the cooking plume. Appliance placement, hood height, overhang, end panels, and air movement nearby all matter. A listed hood’s required airflow or an engineered capture assessment may call for a different design. Do not use the table alone as a fan order.
Duty classification is also important. Light, medium, heavy, and extra-heavy describe cooking duty, not the metal or power rating of the hood. A line with a fryer or griddle may need a different classification from one with lower-grease appliances. Ask the hood manufacturer or design professional to classify the actual appliance line, and confirm the decision with the AHJ.
Select the hood for appliance duty and capture
A hood must suit the appliance line as installed, not just its total length. Match the listed hood to the equipment type, fuel, heat load, and cooking duty. Geometry also matters: an island hood is exposed on more sides than a wall canopy and commonly has a higher table rate.
What affects capture beyond CFM?
Capture is the hood’s ability to contain and remove the rising plume. More airflow does not automatically fix poor geometry. Overhang, mounting height, end panels, appliance arrangement, and cross-drafts can all change how well the hood captures vapors. Use the hood maker’s listed dimensions and clearances rather than assuming a standard overhang or mounting height.
A useful way to review a plan is to trace the plume from each appliance toward the hood. Check that the equipment is within the hood’s listed capture area and that nearby supply-air outlets, doors, or fans will not push the plume sideways. If the design includes solid-fuel equipment, seek specific code and manufacturer guidance; extra requirements may apply.
| Planning scenario | Table-based reference | What to verify |
|---|---|---|
| 10-ft wall canopy, heavy duty | 10 × 400 = 4,000 CFM | Adopted code, appliance classification, listing, and capture |
| 8-ft single island, medium duty | 8 × 400 = 3,200 CFM | Island configuration and listed performance |
| 10-ft wall canopy, extra-heavy duty | 10 × 550 = 5,500 CFM | Duty classification and any solid-fuel provisions |
These calculations illustrate how the reference rates work. They are not equipment selections. A hood designer must also account for duct routing, fan performance, makeup air, and the specific listed hood.
Installation, makeup air, and commissioning
Installation turns the design into a working exhaust system. A compliant system may require a listed hood, grease filters, a suitable exhaust fan, grease duct with required access, and fire suppression. The adopted code, NFPA 96, the hood listing, and manufacturer instructions guide the details. Confirm requirements with the AHJ before construction.
I treat commissioning as a test of the complete air path, not just a fan switch. The exhaust fan must move the intended air through the installed duct, while makeup air replaces the air removed. If these systems are not coordinated, the kitchen can become drafty or the hood may fail to capture vapors even when its nominal CFM appears adequate.
Two illustrative installation checks
These examples are planning scenarios, not reports of actual projects. They show why an airflow number alone is not enough.
- Wall line with a fryer and griddle: The designer records each appliance, confirms the duty classification, and selects a listed wall canopy for the complete line. The team checks the applicable table rate, hood dimensions, duct route, and makeup-air plan before ordering the fan.
- Island cooking line near a supply diffuser: The selected exhaust rate may meet the table reference, yet supply air can push the plume beyond the hood’s capture zone. The installer adjusts diffuser placement as allowed by the design, then recommissions the system under realistic cooking conditions.
Commissioning should include checking fan operation, makeup-air balance, filter placement, and capture with the equipment operating. If smoke or grease-laden vapor escapes, investigate air movement and hood geometry rather than simply increasing fan speed. A qualified hood contractor and the AHJ should review changes that affect the listed system or code compliance.
Grease control, fire protection, and upkeep
Grease exhaust systems need grease removal, suitable duct construction, and access for inspection and cleaning. Automatic fire suppression is also required where applicable. NFPA 96 and local rules govern these protections; commercial cooking suppression systems are commonly UL 300-listed. Confirm the design and inspection requirements with the AHJ and equipment providers.
Grease filters must be correctly seated and kept clean. Follow the filter, hood, fan, and suppression-system instructions, along with required cleaning and inspection schedules. Do not remove filters, reduce exhaust below the approved setting, or disable suppression to address noise, drafts, or energy costs. Those changes can undermine capture or fire safety.
Air discharged near the hood deserves attention, too. A diffuser or other supply-air source can create a cross-draft that pushes the hot plume out of the capture zone. If vapor escapes during operation, check for cross-drafts and verify the system under realistic cooking loads. Have a qualified contractor correct the air balance and recommission it.
FAQ: Type I hood airflow and code
These answers address common questions about Type I commercial hoods. The governing code is the edition adopted locally, not necessarily the newest model-code edition. For a project decision, compare the hood listing and manufacturer instructions with local requirements, then confirm the interpretation with the AHJ.
What does a Type I hood do?
It captures and exhausts grease-laden vapors from cooking equipment. The full system includes the hood, grease removal, exhaust duct and fan, and applicable fire protection.
How many CFM does a Type I hood need?
There is no universal CFM requirement. Common model-code tables use airflow per linear foot and vary by hood configuration and appliance duty. Check the adopted code and listed hood.
What is the common wall-canopy rate for heavy-duty cooking?
A common IMC model-code reference is 400 CFM per linear foot for a heavy-duty wall canopy. Verify the adopted edition, applicable table, hood listing, and project conditions before using it.
Is an island hood’s CFM rate the same as a wall hood’s?
Not necessarily. Common model-code references are higher for single-island hoods than for wall canopies at the same duty level. Confirm the specific configuration and adopted table.
Does every commercial range need a Type I hood?
Not based on the word “range” alone. Type I is used where cooking produces grease-laden vapors. Confirm the appliance duty and cooking process with the hood designer and AHJ.
Can a Type II hood be used over a fryer?
A fryer produces grease-laden vapors and generally calls for a Type I hood. Verify the equipment, hood listing, and local requirements before installation.
Does meeting the table CFM guarantee capture?
No. Hood dimensions, mounting height, overhang, appliance layout, and cross-drafts affect capture. The installed system needs to be checked under operating conditions.
Is makeup air part of a Type I hood design?
Yes. Exhaust removes air from the kitchen, so replacement air must be considered. Poorly placed or excessive supply air can disrupt capture; balance and test the system.
What fire protection does a Type I hood need?
Grease-removal components, duct details, and automatic suppression must follow applicable code and listing requirements. NFPA 96 and the AHJ provide key references; commercial suppression systems are commonly UL 300-listed.
Can I lower the fan speed to reduce noise?
Do not lower exhaust below the approved design setting or disable safety equipment. Ask a qualified hood contractor and the AHJ to evaluate noise, capture, and air balance, then recommission any approved changes.
(This article was written by one of our staff writers, Julian R. Hayes. Visit our Meet the Team page.)
