Ducted or Ductless Comes Down to the Duct Route

Pick a ducted hood if your kitchen can get a duct outside. Ducted venting carries steam, grease, heat, and combustion byproducts out of the house. A ductless model filters grease and odor through a charcoal cartridge, then pushes the rest of the air — moisture included — back into the room you’re cooking in. Ductless earns its place when there’s no route out at all: a cooktop on an interior wall, a condo, a concrete ceiling with nowhere to run a chase. That’s the whole comparison.

What makes it hard is timing. Most homeowners fall for a hood at the showroom, then learn the only way to vent it is a fourteen-foot run through a joist bay that’s already full of plumbing. Sometimes that’s solvable. Sometimes it costs more than the hood did.

What Each Hood Type Takes Out of the Room

Grease is the easy part. Both types catch it, in a metal baffle or a mesh filter you wash in the sink. The difference is everything else rising off the burners. Boiling a pot of pasta puts a startling amount of water vapor into the air. Searing a steak adds smoke and fine particles. A gas flame adds combustion byproducts on top of both.

Only one of the two gets that out of the building. EPA guidance on improving indoor air quality is plain about the mechanism: “Local bathroom or kitchen fans that exhaust outdoors remove contaminants directly from the room where the fan is located.” Exhaust outdoors is doing the work in that sentence. A recirculating hood has no outdoors to exhaust to.

The distinction gets sharper if you cook on gas. EPA guidance on carbon monoxide and indoor air names a specific step for gas cooking: “Install and use an exhaust fan vented to outdoors over gas stoves.” A charcoal cartridge doesn’t do that job. It was never built to.

Moisture is the part people notice a year later. Vapor that stays in the room finds the coldest surface available — window glass, an exterior wall, the underside of the cabinets flanking the hood. In a tight, well-insulated house it has nowhere else to go.

How Much Airflow Does Your Cooktop Need?

Airflow is measured in cubic feet per minute, and the number you need follows the cooking surface underneath the hood rather than the size of the kitchen. A wider cooktop needs more. A high-output gas burner needs more still. Undersizing is the common mistake, though oversizing carries a problem of its own.

Manufacturers publish a recommended airflow range for each range and cooktop they sell. That spec sheet is the honest starting point, and it beats a rule of thumb copied off a forum. Width matters just as much as the fan rating. A hood narrower than the cooking surface lets the plume slip out at the edges before the fan ever sees it.

Mounting height is the third variable and the one that quietly gets missed. Every hood carries a manufacturer-specified height above the cooktop. Hang it higher for headroom and capture falls off fast. If the plan runs toward a professional-style range, the airflow target climbs quickly and the duct has to grow with it — worth settling early when you’re designing a kitchen built around real cooking.

Finding a Duct Route in Your House

Three routes cover most kitchens, and they don’t cost the same.

• Straight out an exterior wall behind the cooktop. Shortest, cheapest, quietest.
• Up through the cabinet and ceiling, then out the roof. Longer, and it needs a roof cap and flashing.
• Island or peninsula. The duct climbs into the ceiling and travels to an outside wall or the roof.

Every elbow costs airflow. So does flexible duct. A short, smooth, correctly sized run moves more air at a lower fan speed, which is also the reason it runs quieter.

What decides the route isn’t the hood you liked. It’s the direction the floor joists run, whether the space above is conditioned or attic, how far the exterior wall sits from the cooktop, and whether that wall is masonry. None of those show up in a rendering. A free kitchen design tool will happily float a hood over an island without ever asking where the duct goes.

When a Hood Moves Enough Air to Pull Back

A powerful hood is a pump. Every cubic foot it pushes outside has to be replaced by a cubic foot coming in from somewhere else. In a drafty older house that air seeps around windows and doors and nobody notices. In a tight, well-sealed house, a strong hood can pull hard enough to put the whole room under negative pressure.

That’s where it turns into a safety question. Negative pressure looks for the easiest opening it can find, and sometimes the easiest opening is a chimney or a water-heater flue. Air comes down the flue instead of going up it, and combustion gases come along. Building codes answer this with makeup air: a dedicated, usually damper-controlled path that lets replacement air in on purpose.

The airflow threshold that triggers a makeup-air requirement varies by jurisdiction, so confirm the local number rather than assuming one. The physics doesn’t vary. Cutting a roof penetration and adding a damper is also well past the point where doing it yourself pays off.

Choose Ducted If, Choose Ductless If

Choose ducted if the cooktop sits on or near an exterior wall, if you cook on gas, or if searing and frying are a weekly habit rather than a holiday event. Choose it too if the house is newer and tight, because that’s precisely where trapped moisture has nowhere to disperse.

Choose ductless if you’re in a condo or a building that won’t permit an exterior penetration, or if the cooktop lands in the middle of a slab-ceiling space with no chase. It’s also the reasonable answer for a light-use kitchen where the cooking is mostly reheating and boiling water.

Decide before the layout locks if you’re still moving walls. The cooktop’s position is the single biggest lever on venting cost, and it’s nearly free to move on paper. Putting the cooktop out in an island is the most expensive venting choice available, and it’s usually made for reasons that have nothing to do with air.

Not sure which bucket your kitchen falls into? That’s a twenty-minute conversation with someone who can look at your joist direction and your exterior wall. Book a kitchen design consultation and get the venting question settled while it’s still cheap to change.

Where a Ducted Hood Loses

Ducted venting isn’t free and it isn’t always graceful. It costs more up front, sometimes substantially, and the gap widens with every foot of duct. It eats cabinet space; a chimney-style hood usually takes the upper cabinet above the cooktop with it, which is a real trade in a small kitchen where every bit of upper storage counts.

A roof penetration adds a flashing detail that has to be maintained like any other. And in some buildings the answer is simply no, regardless of budget.

This is the kind of thing that belongs on a drawing rather than in a conversation. Our design plans mark relocated vents, removed walls, and outlet placement before a single cabinet gets ordered, and they carry a field-verification note because measurements taken on site have a way of correcting measurements taken from a plan. A hood that fits on paper and misses a joist by two inches is a change order nobody wants to sign.

Frequently Asked Questions

Can a ductless range hood be converted to ducted later?

Often yes, if the model is built for it. Many hoods ship convertible, and the change is a matter of a kit and a blower orientation. The hard part was never the hood. It’s opening the wall or ceiling afterward to build the duct path you skipped, with finished surfaces already in place.

Does an over-the-range microwave count as a range hood?

It counts as ventilation, though usually the weakest version available. Combination units sit lower than a dedicated hood, cover a narrower footprint, and move less air. Many are installed in recirculating mode even when a duct is available, so it’s worth confirming which way yours is configured.

How do I know if there’s already ductwork behind my cabinets?

Look outside first. A wall cap or roof cap near the kitchen is a strong sign something was vented at some point. Beyond that, it takes a look inside the cabinet above the cooktop or a small exploratory opening. Existing ductwork is a gift when it’s the right size and in the right place, and neither is guaranteed.

Settle the Vent Before the Cabinets Are Ordered

The hood is the last thing anyone shops for and one of the first things that should be planned. Once the cabinet order is placed and the drywall is closed, the duct route stops being a design question and starts being a demolition question.

If you’re weighing a kitchen project in Crofton or the surrounding area, bring the cooktop question to the table early. Schedule a design consultation and we’ll walk the space, find the honest duct routes, and tell you which hood your house will support before you fall for one that it won’t.