Range hoods don't always have to vent outside, but it depends on your building code and what you're willing to accept in air quality

A ducted range hood that vents to the outside removes heat, moisture, and cooking odors from your kitchen entirely. A ductless (or recirculating) range hood filters the air and pushes it back into the room. Most building codes require ducted venting in new construction and major renovations, but existing kitchens often have more flexibility. The real question is whether you can live with the tradeoffs: ducted hoods work better but cost more to install, while ductless hoods are cheaper and easier but don't remove humidity or all odors.

Key Takeaways

  • Building codes in most jurisdictions require ducted venting for new kitchens or major renovations, but existing kitchens may be grandfathered in under older rules.
  • Ductless range hoods filter and recirculate air instead of removing it, so they reduce odors and grease but don't remove moisture or heat.
  • Ducted installation typically costs $500 to $2,000 more than ductless because it requires ductwork, roof or wall penetration, and sometimes professional installation.
  • If you rent or live in a condo, your lease or HOA rules may prohibit exterior venting or require landlord approval before installation.

What your local building code actually requires

Building codes vary by state, county, and city, so you need to check with your local building department or code official—not a general online source. Most jurisdictions that have adopted the International Residential Code (IRC) require range hoods to be ducted to the outside in new construction and when you're doing a kitchen remodel that includes moving or replacing the hood. Some codes allow ductless hoods only in specific situations, like a rental unit where ducting isn't physically possible.

If your kitchen was built before the current code went into effect, your existing ductless hood is usually legal to keep and replace with another ductless model—this is called being "grandfathered in." However, if you're doing a full kitchen renovation or moving the hood location, the new installation often has to meet current code, which usually means ducting to the outside. Call your local building department and describe what you're planning; they can tell you in one conversation whether you need a permit and what the code requires.

Some jurisdictions have adopted stricter energy codes that require ducted venting specifically because ductless hoods don't remove conditioned air from the home. Others are more lenient. The only way to know is to ask your code official directly.

How ductless hoods work and what they actually remove

A ductless range hood has a charcoal filter (or sometimes a mesh grease filter plus charcoal) that traps grease particles and odor molecules, then a fan that pushes the filtered air back into the kitchen. They're quieter than ducted hoods at the same fan speed, cost less to buy and install, and work in any kitchen layout because they don't need ductwork.

The catch is what they don't do: they remove maybe 50 to 70 percent of cooking odors (depending on filter quality and how often you replace the charcoal), they remove almost no moisture, and they put all the heat from cooking back into your kitchen. If you boil pasta or fry bacon regularly, a ductless hood will not stop your windows from fogging or your kitchen from getting hot and humid. Charcoal filters also need replacing every 3 to 6 months depending on how much you cook, which adds ongoing cost.

Ductless hoods work best in kitchens where cooking is light to moderate, you don't mind some lingering smells, and you have good cross-ventilation from windows. They're also a practical choice if you rent, live in a condo with strict rules, or can't run ductwork to an exterior wall or roof.

Ducted venting: why it works better and what it costs

A ducted range hood pulls air and moisture directly outside through rigid or flexible ductwork, so nothing stays in your kitchen. This removes 85 to 95 percent of odors, eliminates cooking moisture before it can fog windows or damage walls, and keeps heat out of your living space. Ducted hoods are the standard in professional kitchens and high-end homes because they actually solve the problem.

The tradeoff is installation cost and complexity. A straightforward ducted installation—straight ductwork to an exterior wall on the same floor—might cost $500 to $1,000 in materials and labor. A complex installation—running duct through walls, up to the roof, or across multiple rooms—can easily reach $2,000 to $4,000. You also need to account for the hood itself, which ranges from $300 for a basic model to $2,000 or more for a high-end unit.

Ducted hoods also need to be sized correctly for your kitchen. A hood that's too small won't capture steam and smoke; one that's too large will create negative pressure and pull air down your chimney or through other openings. A professional installer can calculate the right size based on your stove type and kitchen layout.

When you can't vent outside: renting, condos, and other restrictions

If you rent, your lease almost certainly prohibits you from cutting holes in walls or roofs for ductwork. Some landlords allow ductless hoods because they're removable and don't damage the building. Check your lease or ask your landlord before buying anything.

Condo owners often face HOA rules that prohibit exterior venting because it affects the building's appearance or envelope. Some HOAs allow ducting only to a shared vent stack or require approval from the board. Others prohibit any exterior modifications. Read your HOA rules or contact the board before planning a ducted installation.

In apartments and condos, a ductless hood is often your only legal option. Some buildings have a shared ventilation system you can tie into, but that's rare and requires professional assessment. If exterior venting is truly off the table, a high-quality ductless hood with regular filter replacement is the practical choice.

Installation: DIY versus hiring a professional

A ductless hood is a straightforward DIY project if you're comfortable with basic wiring and mounting. Most models come with a template; you mark the holes, drill, and bolt the hood to the wall or cabinet. Wiring usually means running a cable to a nearby outlet or hardwiring to a circuit—if you're not comfortable with electrical work, hire an electrician for that part.

Ducted installation is more complex and often worth hiring out. You need to run ductwork (which means cutting through walls or ceilings), seal all joints to prevent air leaks, and make sure the duct terminates properly on the exterior—usually with a damper that closes when the hood is off. Mistakes here lead to backdrafting, air leaks, or moisture problems inside walls. If you're handy and the run is straightforward and straight, you might handle it yourself; otherwise, a professional installer ensures the job is done to code.

Many jurisdictions require a permit for ducted hood installation and a final inspection. This protects you because an inspector will catch problems like improper ductwork or inadequate makeup air. The permit usually costs $50 to $200 and adds a week or two to the timeline.

Makeup air and negative pressure: why they matter

A powerful ducted range hood removes a lot of air from your kitchen. If your home is very tight (well-sealed, modern construction), that removed air has to come from somewhere, and it often comes down your chimney, furnace vent, or other openings—a problem called backdrafting. In extreme cases, this can pull exhaust gases back into your home.

Building codes address this by requiring makeup air in kitchens with very powerful hoods (usually 400 CFM or higher). Makeup air is fresh outside air that enters the home to replace what the hood removes. It can come from an open window, a dedicated duct, or a passive intake. In most residential kitchens with standard-size hoods (200 to 300 CFM), makeup air from a nearby window or door is sufficient.

If you're installing a very large or commercial-style hood, or if your home is extremely well-sealed, ask your installer or code official whether makeup air is required. Ignoring this can create comfort and safety problems.

Frequently Asked Questions

Can I use a ductless hood if my building code requires ducted venting?

Not in new construction or a major renovation where the code applies. However, if you're replacing an existing ductless hood in an older kitchen, you may be grandfathered in. Check with your local building department—they can tell you whether your specific situation requires ducting or allows you to keep a ductless model.

How often do I need to replace the charcoal filter in a ductless hood?

Most manufacturers recommend replacing charcoal filters every 3 to 6 months with regular cooking, or sooner if you cook frequently or fry often. Some filters are washable, but charcoal cannot be cleaned—only replaced. Check your hood's manual for the exact interval and filter cost, which typically ranges from $20 to $60 per filter.

What size ductwork do I need for a ducted hood?

Most residential range hoods use 6-inch or 8-inch round ductwork. The size depends on the hood's CFM (cubic feet per minute) rating and the length of the duct run. Your hood's manual specifies the required duct diameter; using undersized duct reduces performance and increases noise. A professional installer can size the duct correctly for your setup.

Can I vent a range hood into the attic instead of outside?

No. Venting into the attic introduces moisture and cooking odors into an uncontrolled space, which leads to mold, rot, and damage to insulation and framing. Building codes prohibit this. The hood must vent to the exterior—either through a wall or roof—with the duct terminating outside.

What's the difference between a range hood and a microwave hood?

A microwave hood is a small ductless unit built into a microwave above your stove. It has limited suction power and a charcoal filter, so it works like a ductless range hood—it recirculates air rather than removing it. A full-size range hood (wall-mounted, island, or under-cabinet) has much more power and can be either ducted or ductless. Microwave hoods are convenient but less effective for serious cooking.