Quick answer: Before installing commercial kitchen equipment, contractors and kitchen designers should finalize exhaust hood type, duct routing, makeup air balancing, fan placement, fire suppression coordination, grease cleanout access, airflow calculations, utility coordination, and local code compliance. Addressing these details early prevents costly rework, failed inspections, and operational delays once the kitchen opens.
Opening a commercial kitchen involves dozens of moving parts, but few are as easy to overlook—and as expensive to fix later—as the exhaust system. Kitchen designers often focus first on layout, equipment brands, and workflow, leaving ventilation as an afterthought. That’s a mistake. Exhaust systems are governed by strict fire and building codes, and once equipment is bolted down and walls are finished, correcting a poorly planned exhaust setup can mean tearing out ductwork, relocating hoods, or delaying a grand opening by weeks.
Getting exhaust details right before equipment installation saves time, money, and headaches. This guide walks through nine details that should be locked in during the planning phase, not discovered during a failed inspection.
1. What type of exhaust hood does your equipment require?
Not all cooking equipment produces the same type of grease-laden vapor or heat, and the hood you install has to match. Type I hoods are designed for equipment that produces grease and smoke, such as fryers, griddles, and charbroilers. Type II hoods handle heat and steam from equipment like dishwashers or steam-based cooking appliances, without the grease-related fire risk.
Choosing the wrong hood type—or trying to make one hood serve equipment with mismatched needs—is one of the most common planning mistakes. Before any equipment ships, confirm which appliances will sit under which hood, and size the hood length and capture area to match the equipment lineup, not just the available wall space.
2. How will the ductwork be routed, and what clearances does it need?
Duct routing decisions made early can save significant rework later. Grease duct runs must maintain specific clearances to combustible materials, and the routing path affects everything from ceiling height to the structural path through floors and roofs.
Ask these questions during planning:
- Will the duct run vertically through multiple floors, or horizontally through a plenum space?
- What clearance to combustibles does the duct require along its entire path?
- Are there structural beams, sprinkler lines, or electrical conduits that will conflict with the planned route?
Mapping this out digitally, ideally in coordination with mechanical, electrical, and plumbing (MEP) drawings, prevents the exhaust contractor from discovering conflicts mid-installation.
3. Is makeup air balanced against exhaust volume?
Exhaust hoods remove enormous volumes of air from a kitchen, and that air has to be replaced. Without properly balanced makeup air, kitchens experience negative pressure, which can cause doors to stick, pilot lights to blow out, and heating or cooling systems to work overtime pulling in unconditioned outside air through gaps and cracks.
Makeup air planning should account for the total exhaust CFM (cubic feet per minute) generated by all hoods combined, not just the largest one. Kitchens with multiple hood sections often underestimate total exhaust volume, leading to a makeup air system that’s undersized from day one.
4. Where will the exhaust fan sit, and what does the roof curb need?
Exhaust fans are typically mounted on the roof, and their placement affects both performance and neighborly relations. Fans positioned too close to fresh air intakes can recirculate grease-laden exhaust back into the building. Fans placed near property lines or neighboring windows can create odor or noise complaints.
The roof curb also matters. It needs to be structurally rated for the fan’s weight, properly flashed to prevent leaks, and positioned to allow safe access for future cleaning and maintenance. Planning fan placement and curb specifications before equipment arrives avoids a scenario where the fan is ordered but has nowhere appropriate to go.
5. Can grease ducts be accessed for cleaning after installation?
Grease duct cleanout access is a code requirement, not an optional convenience. The National Fire Protection Association’s NFPA 96 standard for ventilation control and fire protection of commercial cooking operations requires accessible cleanout openings along the duct run, especially at changes in direction.
If ductwork is boxed in behind finished ceilings or walls without planning for access panels, the kitchen will fail inspection or require costly demolition later to create compliant access points. Confirm cleanout locations with the exhaust contractor before framing or finish work begins.
6. Have exhaust airflow requirements been calculated for the actual equipment lineup?
CFM requirements depend on the type, size, and heat output of the cooking equipment underneath the hood, not a generic estimate. A hood sized for light-duty equipment like ovens and steamers will be undersized if the kitchen later swaps in heavy-duty charbroilers or solid fuel cooking equipment.
This is why airflow calculations should happen after the equipment list is finalized, not before. If equipment selections change during planning, revisit the exhaust calculations to confirm the hood and fan can still handle the updated load. Choose a higher-capacity exhaust fan if there’s any chance equipment will be upgraded or expanded later, since retrofitting fan capacity is far more disruptive than sizing correctly the first time.
7. How will the exhaust system coordinate with fire suppression?
Commercial kitchen exhaust systems over Type I hoods must coordinate with a fire suppression system, typically a wet chemical system compliant with UL 300 standards. The suppression system needs to shut down fuel and electrical supply to the cooking equipment automatically when activated, and it needs nozzle placement that matches the exact equipment layout underneath the hood.
If equipment positions shift after the suppression system is designed, nozzle coverage can end up misaligned, leaving gaps in fire protection. Finalize equipment placement before the fire suppression contractor designs nozzle locations, and revisit the design if equipment moves even slightly during final installation.
8. Are gas and electrical utilities coordinated with hood and duct placement?
Exhaust hoods, ductwork, and the equipment underneath all compete for space with gas lines, electrical conduit, and plumbing. A duct run planned without checking utility drawings can end up crossing paths with a gas line that needs rerouting, adding cost and delay.
Coordinate utility rough-in locations with the exhaust system layout early, ideally at the same time equipment cut sheets are being reviewed. This is especially important for gas equipment, since shutoff valve locations and connection points need to remain accessible even after the hood and duct are installed.
9. Does the exhaust design meet local code and AHJ requirements?
Building codes for commercial kitchen exhaust vary by jurisdiction, and the authority having jurisdiction (AHJ) may have specific interpretations or additional requirements beyond the base code. Some jurisdictions require additional fire dampers, specific duct gauge thickness, or particular roof termination heights that go beyond NFPA 96 minimums.
Schedule a pre-design meeting with the local fire marshal or building department when possible. Confirming code requirements before equipment installation—rather than during final inspection—avoids the scenario where an inspector flags an issue after ductwork is already sealed and equipment is already running.
Plan the exhaust system before you plan the kitchen layout
Commercial kitchen exhaust systems touch nearly every other system in the building: structural, electrical, plumbing, and fire safety. Treating exhaust as a detail to solve after equipment selection is one of the most common—and costly—mistakes in commercial kitchen design.
The nine details above (hood type, duct routing, makeup air, fan placement, cleanout access, airflow calculations, fire suppression coordination, utility coordination, and code compliance) should all be resolved before equipment is ordered, not after it arrives on-site. Bring the exhaust contractor, mechanical engineer, and equipment vendor into the same conversation early, and confirm every equipment change gets reflected in the exhaust design. A kitchen built this way opens on schedule, passes inspection the first time, and runs safely for years to come.
Frequently Asked Questions
What happens if a commercial kitchen exhaust system is undersized?
An undersized exhaust system will fail to capture smoke, heat, and grease effectively, leading to visible smoke buildup, grease accumulation in unintended areas, and potential failure of health and fire inspections. It can also violate NFPA 96 requirements, putting the kitchen’s operating permit at risk.
How much does it cost to fix exhaust problems after installation?
Costs vary widely depending on whether the fix requires simple adjustments (like rebalancing airflow) or major work (like relocating ductwork or replacing an undersized fan). Rework after finishes are installed is significantly more expensive than addressing the same issue during the planning phase, since it often involves demolition and re-inspection.
Who should be involved in planning a kitchen exhaust system?
Exhaust planning works best with input from the mechanical engineer, exhaust hood contractor, fire suppression contractor, equipment vendor, and the local fire marshal or building department. Involving all parties before equipment is ordered helps catch conflicts early.
Can makeup air problems be fixed after a kitchen is already operating?
Yes, but it typically requires adding or resizing makeup air units, which can mean cutting new roof penetrations or upgrading ductwork. It’s far less disruptive to size makeup air correctly during initial planning than to retrofit it into a functioning kitchen.
Does every commercial kitchen need a Type I hood?
No. Type I hoods are required for equipment that produces grease-laden vapors, such as fryers and griddles. Kitchens using only heat- or steam-producing equipment, like ovens and steamers, may only need a Type II hood. The equipment lineup determines which hood type applies.