Why Your New Kitchen Might Need a Bigger Range Hood Than You Think

Range hoods are usually one of the last things homeowners choose in a kitchen remodel. They pick one from a showroom or a photo because it looks right and has a big CFM number on the spec sheet. Then the kitchen is finished, and the smoke from searing a steak still drifts into the living room.

The short answer is that the hood that fits the design often isn’t the one that clears the kitchen. There are three reasons. First, the hood’s size and shape affect how well it captures smoke more than its fan rating does. Second, the duct path through your house decides how much airflow you actually get. Third, California’s Energy Code now judges hoods by performance, in ways that depend on the size of your home and what fuel you cook with.

In a San Francisco Victorian or Edwardian, or a mid-century home in Marin, all three factors tend to push toward a bigger hood. Often that means a wider or deeper hood rather than a more powerful one. If you’re still weighing whether ventilation deserves attention in your remodel at all, our earlier post on why kitchen ventilation matters in a remodel covers the basics. This article picks up where that one leaves off.

“Bigger” usually means wider and deeper, not stronger

Cooking produces a rising plume of heat, moisture, grease, and particles. That plume spreads out as it rises. A hood’s first job is to contain it long enough for the fan to pull it out. If the hood is exactly as wide as the cooktop and mounted near the top of its allowed height, the plume can spill past the edges before the fan catches it. Adding more fan power doesn’t fix a hood that’s too small to hold the plume.

A few factors determine whether a hood captures well:

Width. A hood at least as wide as the cooking surface is the baseline. Many designers extend it a few inches past each side, especially over a professional-style range.

Depth. Shallow hoods tend to miss the front burners, which are the ones people use most.

Mounting height. Lower captures better. Stay within the manufacturer’s recommended range for your cooktop.

Location. A wall-mounted hood captures better than an island hood because the wall blocks drafts from one side. Island hoods usually need to be larger to perform the same way.

So when a kitchen needs a “bigger” hood, the useful question is usually whether the hood is big enough to hold what the cooktop produces. How many CFM it has is a secondary question.

Rated airflow isn’t the same as delivered airflow

A hood’s airflow rating comes from a lab test at a specific amount of duct resistance. Your house adds its own resistance: every foot of duct, every elbow, any reducer from a larger outlet down to a smaller duct, and the cap on the exterior wall or roof. The farther and more awkward the route, the less air the hood actually moves.

California’s code recognizes this gap. The airflow required by the Energy Code is the quantity of indoor air exhausted by the ventilation system as installed in the dwelling unit. Installers can confirm it in one of two ways. They can measure airflow with a flow hood, flow grid, or other measuring device, or, as an alternative, install an exhaust fan and duct system that conforms to the specifications of Table 150.0-H, the code’s prescriptive duct-sizing table.

In practice, a hood that looks strong on paper can underperform once it’s connected to a small or long duct. The duct route is part of the hood decision, not something the installer works out later.

What California’s Energy Code asks of a range hood now

This is where many remodels get caught off guard. Under California’s residential standards, the installed range hood model must be rated by the Home Ventilating Institute (HVI) or the Association of Home Appliance Manufacturers (AHAM) and meet either a minimum ventilation airflow rate or, alternatively, a minimum capture efficiency. You can look up a specific model’s certified ratings in the HVI product directory before you commit to it.

The required level is set by a state table of range hood airflow rates and capture efficiency ratings, organized by dwelling unit floor area and kitchen range fuel type. The size of your home and whether you cook on gas or electric both change what counts as a compliant hood. The 2025 version of the California Building Energy Efficiency Standards applies to projects permitted under it. The state’s single-family compliance forms carry a January 1, 2026 date.

For remodels, the rules for altered ventilation systems depend partly on the home’s permit history. When a kitchen fan is altered or replaced:

• Dwellings that were required by a previous building permit to comply with the kitchen exhaust requirements must meet or exceed the applicable airflow or capture efficiency requirements.
• Dwellings that were previously required to install a vented range hood or other kitchen exhaust fan must install a replacement that meets or exceeds the airflow required by the previous permit, or 100 cfm, whichever is greater.
• Dwellings that were never required to have a kitchen exhaust system under either condition are not required to comply with those requirements.

In every case, new or replacement exhaust fans must be rated for airflow and sound.

How these rules apply to your project depends on its scope, the home’s permit history, and your building department. A full gut remodel, a kitchen relocated during a larger renovation, and a new kitchen in an ADU or addition may all be treated differently from a simple hood swap. Third-party field verification may also be required. Some energy consultants note it also applies to ADU projects that include a kitchen.

Treat this section as orientation and confirm the requirements for your address. In San Francisco, that means the Department of Building Inspection. In unincorporated Marin, it means the County of Marin’s Community Development Agency. Incorporated towns like Mill Valley and San Rafael run their own building departments.

Why these Marin and San Francisco homes push the numbers up

Long duct routes in San Francisco row houses and flats. Many Victorians and Edwardians sit on narrow lots, with side walls at or near the property line and kitchens toward the middle or back of the building. Getting a duct outside can mean a long horizontal run across joists, a chase up through a flat above, or a route to the rear wall. Code rules on where exhaust can terminate relative to property lines, windows, and doors can narrow the options further, and those details vary with the building and the jurisdiction. Longer runs with more elbows deliver less air, so the hood either needs more headroom in its rating or a better route. It’s one of several constraints we cover in our guide to remodeling a historic home in San Francisco, and it shapes much of our kitchen remodeling work in San Francisco.

Opening up the floor plan. Removing the wall between kitchen and dining room is one of the most common changes in these houses. If you’re considering opening up a kitchen to the rest of the house, know that cooking smoke and moisture will have a much larger area to spread into. The Energy Code distinguishes enclosed and nonenclosed kitchens in its ventilation tables. In practical terms, capture matters more when there’s no wall to contain what escapes.

Smaller homes and units. Because the required range hood rating is tied to the home’s floor area, an SF flat or condo can face a different standard than a larger single-family house with the same cooktop. Homeowners are often surprised that a hood that works fine in a large suburban kitchen may not be the right choice in a compact San Francisco unit.

Mid-century roofs and ceilings in Marin. Many mid-century homes in Mill Valley, San Rafael, Novato, and elsewhere in the county have flat or low-slope roofs, exposed beams, or vaulted ceilings with no attic above the kitchen. There may be no hidden path for a duct. A roof penetration on a low-slope roof has to be flashed and waterproofed carefully, and a wall route may run into walls of glass. Hillside homes add another layer when the kitchen sits under a deck or an upper floor. Our Marin County remodeling page covers more of what makes projects there distinct.

Gas cooking. Gas combustion adds its own byproducts to the air, and fuel type is one of the variables in the state’s range hood table. If you’re also weighing a switch to induction, make that decision before you choose the hood, because it can change the requirement. Some local jurisdictions in Marin and San Francisco have adopted their own energy ordinances that affect gas in certain projects, so check what applies at your address.

The makeup air question

Every cubic foot of air a hood pushes outside has to be replaced. In a drafty house, it leaks in through gaps. A remodeled home with new windows, insulation, and air sealing is tighter, and a strong hood can depressurize it. Symptoms include a hood that underperforms, doors that whistle or resist opening, and in more serious cases, gas appliances like a naturally vented water heater or furnace pulling exhaust back into the house instead of sending it up the flue. Tighter homes also hold onto moisture differently, which is part of why moisture management in a Bay Area remodel deserves attention alongside ventilation.

That’s why codes address makeup air for high-capacity hoods. Under the widely used model residential code, kitchen exhaust hood systems capable of exhausting more than 400 cfm must be provided makeup air at a rate approximately equal to the exhaust. Green Building Advisor’s overview of makeup air for kitchen exhaust is a good plain-language explainer. California’s mechanical code and your local building department determine exactly how this applies to your project.

The practical takeaway: pushing a hood’s fan rating higher can add a makeup air system, which means more coordination, more cost, and possibly another trade on the project. Often the better move is to improve capture with a wider, deeper, properly mounted hood and a shorter, well-sized duct, rather than adding fan power. If a high-capacity hood is the right call, plan for makeup air during design, not after the cabinets are in.

What to decide before demolition, and what can wait

Decide before demolition or cabinet ordering:

• Hood type (wall, island, or an insert inside a custom enclosure), width, depth, and mounting height
• Whether the cooktop is gas or induction
• Duct size, full route, and exterior termination point (wall or roof)
• Whether makeup air is likely to be needed, and how it would be provided
• Electrical circuit for the hood, plus any interlock wiring for makeup air
• Structural blocking for a heavy hood, especially island and custom hoods
• Upper cabinet layout, since cabinets on either side depend on the final hood dimensions

These can wait until later:

• The finish of a custom hood cover (plaster, wood, metal), as long as the insert dimensions are locked in
• Trim and decorative details
• Final light and control preferences, if they don’t change the model

A common source of delay is choosing the hood after the cabinets are ordered. A custom hood enclosure is built around a specific insert, and that insert has to be known before the cabinet shop finalizes drawings.

Questions to ask before you approve the ventilation scope

• What duct size and route are planned, and how many elbows are in it?
• Is the hood you’re recommending listed in the HVI or AHAM directory at the rating our project needs?
• How will installed airflow be confirmed?
• Is makeup air likely to be required with this hood, and if so, how will it be provided?
• Where will the duct exit the house, and how will that penetration be flashed or sealed?
• Does the proposal cover the hood as an allowance only, or does it also include the ductwork, exterior cap, electrical, and any makeup air?

That last question matters when comparing bids. Two proposals can list the same hood allowance and very different ventilation scopes.

Common questions about range hoods in a kitchen remodel

Can I use a recirculating (ductless) range hood instead?
A recirculating hood filters air and returns it to the room rather than exhausting it outside. California’s range hood provisions are written around vented hoods, and compliance checklists commonly tell specifiers to confirm the hood is a ducted model, not a recirculating one. If venting outside is difficult in your home, ask your contractor and building department how a recirculating option would be treated before you plan around one.

Is a downdraft vent a good option for an island?
Downdraft systems are allowed in some configurations. California’s tables list other kitchen exhaust fans, including downdraft, at 300 cfm for demand-controlled systems. Because smoke and steam rise, a downdraft has to pull them sideways and down, and it generally captures less effectively than a well-sized overhead hood, especially from tall pots.

If I switch to induction, can I use a smaller hood?
Possibly. Fuel type is one of the variables in the state’s range hood table, and induction doesn’t produce combustion byproducts. Cooking still produces grease, moisture, and particles, though, so capture still matters. Size the hood for how you actually cook.

Can I reuse the existing duct?
Sometimes, but many existing kitchen ducts are undersized, poorly sealed, or routed in ways that cut airflow. A new hood connected to an old, small duct is one of the most common reasons a new kitchen underperforms. Have the existing duct evaluated as part of the design, not after the hood arrives.

Will my new hood need to be tested?
It depends on your project scope and jurisdiction. Some projects require the installed airflow to be measured or third-party field verification. Ask about this during planning so the hood and duct are chosen with verification in mind.

A practical next step

If you’re planning a kitchen remodel in Marin County or San Francisco, bring your cooktop and hood choices, even tentative ones, to your first planning walkthrough. Walking the duct route in the actual house is the fastest way to find out whether the hood you want will perform the way you expect. Our kitchen remodeling page explains how HTS plans and sequences kitchen projects, including ventilation, before construction starts.

This article is general educational information. Ventilation, energy code, and permit requirements depend on your property, its permit history, your plans, and your local building department. Confirm project-specific requirements with your jurisdiction and the licensed professionals on your project.