A powered cooker hood is never connected to a shared extract system: article 14 of the French order of 24 March 1982 bans connecting an individual powered device to a communal air extraction installation, whether mechanical or passive. The one case where a hood and the kitchen extract coexist is set out in article 3, and it covers a hood connected by design to the extract without a fan of its own: it then allows a lower kitchen extract rate.
Understanding hood types and their impact on kitchen ventilation
Ducted hood: when air is expelled outside, and what that means for mechanical ventilation
A ducted hood captures fumes and expels the air outside through a dedicated duct. It's effective against odors and especially steam. In a home fitted with mechanical ventilation, watch out for an air imbalance if the hood's airflow is high. You need a sufficient air inlet and, in collective housing, must avoid any connection to the shared ventilation ductwork.
Recirculating hood: grease filter, carbon filter, and limits in real use
A recirculating hood sends the air back into the room. The grease filter traps particles, the carbon limits odors, but none of that deals with the VOCs and formaldehyde in the room, which only leave through the extract. In practice, steam stays in the kitchen, so the mechanical ventilation has to do the work. Keep maintenance in mind. The carbon filter needs regular replacement, otherwise efficiency drops quickly.
Airflow, pressure loss, and noise: what to check before choosing a hood
Look at the usable airflow, not just the maximum. A long, narrow duct or one with bends increases pressure loss and raises noise levels. Aim for a simple installation, a backdraft damper, and a bearable noise level, especially for daily use.
The three arrangements, and which one is lawful
The confusion comes from "hood" meaning two very different objects: a box that recirculates, and a box that blows into a duct. The second is an individual powered device, and it is the one article 14 targets.
| Arrangement | What it is | Verdict |
|---|---|---|
| Recirculating hood, charcoal filter | nothing discharged, air returns to the room | always possible, does not remove the need for a kitchen extract valve |
| Powered hood connected to the ventilation duct | individual powered device on the communal installation | banned, article 14 |
| Powered hood on its own dedicated duct, discharging through the wall or roof | a network independent of the ventilation system | possible, and the ventilation installation is still owed separately |
| Hood connected by design to the kitchen extract, with no fan of its own | planned into the network from the outset | possible, and the only case that opens the door to a reduced extract rate |
The last row is the one that saves money, and the one everyone forgets. Article 3 allows a lower kitchen rate where a hood is connected by design to the extract, the reduction being set according to the hood's efficiency under terms approved by the ministers responsible for construction and health. In other words this is not a tolerance to be decided on site: it is justified by the product and its documentation.
What it changes in your quotation and at handover
Three practical consequences. First, a recirculating hood does not replace the kitchen extract valve: every service room must have one, and the kitchen is a service room. Second, if the client insists on an extracting hood, the dedicated duct goes on the quotation, with its wall or roof terminal, its clearances and its protection: it is an extra package, not a free variant, and it joins the works plan like any other ancillary trade priced alongside the main work. Third, in a block of flats the question does not even arise, since putting a powered hood on the communal system upsets the airflow balance of every dwelling on the riser.
The drafting habit that avoids the dispute: state in writing, on the quotation, that the hood supplied is recirculating, or that the dedicated duct is included, or that it is excluded. A client who discovers afterwards that they cannot cut into their facade comes back to you, not to the regulation.
Hood and mechanical ventilation compatibility: what works, what causes problems
Single-flow ventilation: risks of imbalance and odor backflow into the home
With single-flow mechanical ventilation, a ducted hood creates a strong depressurization. If the air inlets are insufficient, air can flow back through the vents or ducts, bringing odors and moisture with it. Avoid connecting the hood to the ventilation ductwork. Prefer a recirculating hood, or an extraction on a dedicated duct.
Heat-recovery ventilation: precautions against clogging and malfunctions
With heat-recovery (double-flow) ventilation, airflows are balanced. A hood connected to this network can send grease and steam into the ducts, causing rapid clogging of the filters and disrupting the heat exchanger. The safest option remains a recirculating hood with well-maintained filters. For ducted extraction, keep an independent outlet with a backdraft damper.
Airtight homes and air inlets: why the hood can put the system at fault
In an airtight home, the hood can draw in more air than what's coming in. The result: slamming doors, backflow into a combustion appliance, and a mechanical ventilation system thrown off balance. Plan suitable air inlets, or a dedicated air supply near the kitchen. Opening a window while cooking remains a simple test.
Installation best practices: ensuring effective and compliant ventilation
Roof or facade outlet: distance rules, backdraft damper, and sealing
For direct extraction, favour a roof outlet. On a facade, check local rules and keep sufficient distance from openings and air inlets. Fit a suitable backdraft damper, then take care with sealing using a compliant penetration and cowl. The goal is to prevent backflow and infiltration.
Hood extraction ductwork: diameter, length, bends, and reducing losses
A short, smooth duct run changes everything. Keep the correct diameter specified by the manufacturer, often 125 or 150 mm. Limit the length, reduce the number of bends, avoid reducers and flexible accordion ducting. In unheated spaces, insulate the duct and provide a slight slope toward the outside to limit condensation.
Coordination with mechanical ventilation: don't tap into it, manage airflow, and secure operation
Do not connect the hood to the ventilation ductwork. Grease and airflow overload degrade the system. Set the ventilation system according to its vents, and ensure sufficient air inlets when the hood is running. With a combustion appliance, check draft safety and the manufacturer's specifications.
Special cases: gas, heat pumps, stoves, and other appliances sensitive to depressurization
Kitchen with gas: attention to air supply and combustion product evacuation
With a gas hob, combustion consumes oxygen and generates moisture and pollutants. An extraction hood is useful, provided you keep a functional air inlet (grilles, tilt-and-turn window, dedicated supply). If air is lacking, the flame degrades and emissions increase.
Boiler, stove, insert: preventing backflow and securing the air intake
The risk is backflow of fumes when the mechanical ventilation or the hood puts the home under depressurization. Favour room-sealed appliances, or provide a direct air supply. After the work, test under real conditions (ventilation running, hood running, doors closed) and check the draft and the flue system. To frame the points of attention, you can also consult the regulatory obligations and frequency.
Homes renovated in 2026: reinforced airtightness and the need for well-set ventilation
In 2026, airtightness is often reinforced. The house becomes a thermos, so ventilation must be set and balanced. Measure the airflows, keep air passages (door undercuts, transfer grilles), and avoid overly powerful extraction that destabilizes sensitive appliances. The kitchen is precisely one of the wet rooms the survey documents, with its vent, the air inlets to create on the dry-room side and the combustion safety checks.
Maintenance and settings: keeping a performant hood without penalizing the ventilation system
Cleaning filters and the hood: frequency, signs of clogging, good habits
A clogged hood draws less air and often pushes people to raise the speed setting. Clean the metal filter every 3 to 4 weeks (more often if frying regularly). Telltale signs: greasy film, droplets, increasing noise, lingering odors. Wipe the visor and underside after cooking, and keep filters well dried before reassembly.
Ventilation check: mechanical ventilation vents, air inlets, and airflows to monitor
The hood should not "pump" the air that the mechanical ventilation is supposed to extract. Check the air inlets of dry rooms, making sure none are blocked or taped over. In the kitchen, check that the ventilation vent stays clean and audible, even with the hood on low speed. If doors slam or whistle, that signals a lack of fresh air.
On-site diagnosis: symptoms, common causes, and quick fixes for the client
Common symptoms: odor backflow, condensation, reversed draft, a draft sensation near the vents. Causes: saturated filters, a blocked damper, the hood too often on "boost," a pinched duct, blocked air inlets. Quick actions: cleaning, repositioning the grilles, switching to speed 1 or 2, and a simple smoke test to check the direction of airflow.
