Where your stove hood vents determines what you install and how much work it takes

A stove hood must move cooking smoke, steam, and odours somewhere. That somewhere is either outside your home through ductwork, or back into your kitchen through a filter. The vent path you choose depends on your home's structure, your budget, and whether you rent or own. Outside venting (called ducted or exhaust venting) removes moisture and odours completely but requires cutting through walls or ceilings and running metal duct to the exterior. Recirculating hoods filter the air and push it back into the room, which costs less to install but requires regular filter changes and does not remove moisture as effectively.

Most building codes require ducted venting in new construction and major renovations, though recirculating hoods are allowed in some rental situations and older homes. The choice affects not just installation but long-term maintenance, energy use, and how well the hood actually works.

Key Takeaways

  • Ducted hoods vent to the outside through metal ductwork and remove moisture, odours, and heat completely; recirculating hoods filter air and return it to the kitchen, requiring filter replacement every one to three months.
  • Ducted venting requires a hole through an exterior wall or roof, so installation difficulty depends on your home's construction and whether you can run duct in a straight path with minimal bends.
  • Ductwork diameter (typically 6 inches or 8 inches) must match your hood's outlet, and undersized or overly long duct reduces airflow and makes the hood less effective.
  • Recirculating hoods work best in kitchens with good cross-ventilation from windows or doors, because they cannot remove moisture the way ducted hoods do.
  • Renters should check their lease before installing any vent system; many landlords prohibit ducted venting but allow recirculating hoods.

Ducted venting: routing duct to the outside

Ducted hoods move air out of your home through metal ductwork that runs to an exterior wall or roof. The duct connects to the hood's outlet (usually on the back or bottom) and terminates outside through a wall cap or roof flashing. The most direct route is best: a straight run from the hood to the outside wall, with as few bends as possible. Each 90-degree bend reduces airflow, so if your hood is far from an exterior wall or you must route duct through cabinets, joists, or around obstacles, the hood will work less efficiently.

Duct diameter matters. Most residential hoods have a 6-inch or 8-inch outlet. Using undersized duct (for example, 6-inch duct on an 8-inch hood) creates a bottleneck and forces the motor to work harder. Oversized duct is wasteful but does not harm performance. Flexible duct is easier to install around tight spaces, but rigid metal duct (galvanized steel or aluminium) resists collapse, moves air more smoothly, and lasts longer. Many building codes prefer rigid duct for this reason.

The exterior termination must have a damper or flapper that closes when the hood is off, preventing cold air, rain, and pests from entering your home. Most wall caps and roof flashing include a damper built in. Check that it moves freely and seals completely when closed.

Recirculating hoods: filtering and returning air to the kitchen

Recirculating hoods pull air through a filter and push it back into the room without venting outside. They use charcoal or carbon filters to absorb odours and grease filters (usually mesh or baffle-style) to catch particles. Because no ductwork is required, installation is simpler: you mount the hood to the wall or cabinet, plug it in, and it is ready to use. This makes recirculating hoods popular in rentals and in kitchens where running duct to the outside is impractical.

The trade-off is maintenance and moisture. Recirculating hoods do not remove steam or humidity, so they work best in kitchens with windows or doors that can be opened during cooking. The charcoal filter must be replaced every one to three months depending on cooking frequency; the grease filter can usually be washed and reused. If you skip filter changes, the hood becomes less effective and odours linger. Over time, moisture can also accumulate in cabinets above the hood if there is no outside venting.

Recirculating hoods are quieter than ducted hoods because they do not have to push air against the resistance of ductwork and exterior dampers. They also do not pull conditioned air (heated or cooled air) out of your home, which can be an advantage in very cold or hot climates.

Choosing between ducted and recirculating: what to consider

Start with your home's structure. If you own and your kitchen is on an exterior wall, ducted venting is usually the better choice because it removes moisture and odours completely. If your kitchen is in the centre of your home or far from an exterior wall, running duct becomes complicated and expensive; recirculating may be more practical. If you rent, check your lease. Most landlords prohibit cutting holes in exterior walls, which rules out ducted venting. Recirculating hoods are usually allowed because they require no permanent changes.

Consider your cooking habits. If you cook frequently or use high-heat methods like frying or broiling, a ducted hood will keep your kitchen more comfortable and prevent moisture buildup in cabinets and walls. If you cook occasionally and have good cross-ventilation from windows, a recirculating hood may be sufficient. Budget also matters: ducted hoods cost more to install because of ductwork, labour, and potential wall or roof work. Recirculating hoods have lower upfront costs but higher ongoing costs for filter replacement.

Building codes in your area may also decide for you. Many jurisdictions require ducted venting in new construction or when a range hood is added during a renovation. Check with your local building department before you buy.

Installing ducted venting: the basic steps

If you are installing a ducted hood yourself, start by measuring the distance from the hood to the nearest exterior wall or roof. Determine the shortest, straightest path. Mark where the duct will exit on the outside, then drill a pilot hole from inside to outside so you can locate it from the exterior. From outside, cut or drill the hole to match your duct diameter (usually 6 or 8 inches). Install the wall cap or roof flashing, sealing around it with caulk or flashing tape to prevent water leaks.

Inside, connect the duct to the hood outlet using duct clamps or duct tape (metal tape, not cloth). Run the duct along the path you marked, securing it with duct hangers every 3 to 4 feet to prevent sagging. Minimize bends; if you must turn, use a 45-degree elbow rather than a 90-degree one, or use two 45-degree elbows to create a gentler curve. Connect the far end of the duct to the wall cap, again using clamps and sealing any gaps with duct tape or caulk.

Before you close up walls or ceilings, test the hood. Turn it on and feel for air movement at the exterior cap. If airflow is weak, check for kinks in the duct, a closed damper, or a filter that needs cleaning. If you are not confident in your ability to cut through walls or work at height, hire a professional. A poorly installed duct can reduce hood performance by half or more.

Maintaining ducted and recirculating hoods

Ducted hoods require less frequent maintenance than recirculating ones, but they still need attention. Clean the grease filter (usually removable and dishwasher-safe) every month or when it looks clogged. Check the exterior damper twice a year to make sure it moves freely and closes completely. If you notice reduced airflow, the duct may have accumulated grease buildup inside; this is rare in residential kitchens but can happen if you cook very frequently. A professional can clean the duct if needed.

Recirculating hoods need more regular care. Wash the grease filter monthly in hot soapy water or the dishwasher. Replace the charcoal filter every one to three months; the exact interval depends on how often you cook and how much odour you notice. Some filters are washable and reusable; most are disposable. Check the manufacturer's instructions for your model. If you neglect filter changes, the hood will not remove odours and may start to smell itself.

Common problems and how to fix them

Weak airflow is the most common complaint. In a ducted hood, check the grease filter first—a clogged filter blocks air. Next, inspect the duct for kinks, crushing, or disconnections. Make sure the exterior damper is opening fully. If the duct is very long or has many bends, the hood may straightforward be undersized for the run; upgrading to a higher-CFM (cubic feet per minute) hood can help, but this is expensive. In a recirculating hood, a clogged charcoal filter is usually the culprit; replace it and airflow should improve.

Noise is another issue. Ducted hoods are inherently louder than recirculating ones because they push air against resistance. If a ducted hood is unusually loud, check for loose duct clamps, a partially closed damper, or duct that is kinked or undersized. Recirculating hoods should be quiet; if yours is loud, the motor may be failing or the filter may be so clogged that the motor is straining.

Odours lingering in the kitchen suggest either a clogged filter (in either type) or insufficient venting. In a recirculating hood, no amount of filter replacement will help if the kitchen has no windows or doors for cross-ventilation. In a ducted hood, a closed or stuck damper can trap odours inside the duct. Open the damper manually to test; if it does not close on its own, it may need replacement.

Frequently Asked Questions

Can I install a ducted hood if my kitchen is not on an exterior wall?

Yes, but it is more complex and expensive. You must run duct through walls, cabinets, or the attic to reach an exterior wall or roof. The longer the run and the more bends required, the less efficient the hood becomes. In some cases, a recirculating hood is more practical.

Do I need a permit to install a range hood?

It depends on your local building code. Many jurisdictions require a permit for any work involving ductwork or holes in exterior walls. Check with your local building department before you start. A permit usually means an inspection, which ensures the work is safe and up to code.

Can I use flexible duct instead of rigid duct?

Flexible duct is easier to install around obstacles, but rigid metal duct is preferred because it resists collapse and moves air more smoothly. If you use flexible duct, keep it as straight as possible and support it every few feet to prevent sagging. Never crush or kink it, as this reduces airflow significantly.

How often should I replace the charcoal filter in a recirculating hood?

Most charcoal filters last one to three months depending on cooking frequency and the types of food you cook. Frying and broiling clog filters faster than boiling or baking. If you notice odours are not being removed, replace the filter. Some filters are washable; check your hood's manual to see if yours can be cleaned and reused.

What is CFM and why does it matter?

CFM stands for cubic feet per minute, a measure of how much air the hood moves. A higher CFM means the hood can clear smoke and odours faster. Most residential hoods range from 300 to 600 CFM. If your duct is very long or has many bends, you may need a higher CFM hood to maintain adequate airflow. Check the hood's specifications and compare them to the duct run you are planning.