Probably the most important code requirement for range hoods is that they should vent outdoors.
Another important code is on the duct length and diameter of kitchen hoods.
The in-wall range hood duct should be made out of smooth metal and with a minimal amount of turns.
As a home inspector, I have inspected many range hoods over the years, and clients frequently ask me about building codes. Even though inspectors aren’t code inspectors, we do like to familiarize with building codes and best practices.
In this HomeInspectorSecrets.com code guide, I will go over…
- Minimum duct length & diameter
- Minimum CFM or fan speed
- How range hoods vent to the outside
- Makeup air systems for high powered vent hoods
Kitchen Hood Vent Codes Are Based On The IRC And Your Local Code
7 Building Codes For Kitchen Vent Hoods
Makeup Air Venting Code Prevents Carbon Monoxide Poisoning
Kitchen Hood Vent Codes Are Based On The IRC And Your Local Code
Range hood vent code requirements are laid out in the IRC or the International Residential Code.
The IRC is a ‘model code’ that many U.S. states and counties base their code on. For the final say on any code matter, you will need to consult your local state or city building codes or even a quick call to your local building department.
Even though I summarize the code requirements (I just looked at some of the most important issues), this isn’t exhaustive of every single code and exception.
As a side note, older houses are almost usually ‘grandfathered in’ and not required to adhere to newer code requirements except for new installations.
Read Also >> What Are The Building Codes For Dryer Vents?
7 Building Codes For Kitchen Vent Hoods
1. Must Vent To Outside
Range hoods always need to vent to the exterior. They can’t exhaust into an attic, a crawlspace, or inside a ceiling cavity.
The main code exception is for ductless or recirculating range hoods as long as they are listed and designed for that type of installation. Recirculating range hoods always require the addition of a carbon filter which helps catch smoke and smells.
Here are a few other code requirements on how range hoods exhaust…
- Interior of the duct should be smooth (no ridges)
- Range hood duct needs to be air tight
- Hood needs to have a backdraft damper (a damper or ‘flap’ closes the vent when the hood is not in use)
- Exhaust duct needs to be independent and not connected to any other exhaust system such as a bathroom fan
Read Also >> Do Kitchen Vent Hoods Have To Be Vented Outside?
2. Ducting Material
Range hood ducts always need to be either galvanized steel, stainless steel, or copper.
The one big exception to this code is if the range hood is a downdraft type (it sucks in air downwards and the vent goes into the floor).
With a downdraft hood, it is permissible to use PVC plastic piping instead of metal under certain conditions.
3. Makeup Air System May Be Required
If you have a range hood that is rated at 400-cfm or greater, you may be required to have a makeup air system installed. Makeup air systems are automated devices with dampers that brings in fresh outdoor or to replace the air exhausted by the range hood.
This code requirement only applies to gas or propane ranges and if it isn’t already direct vented.
The makeup air unit also needs to have a damper which closes when not in use so outdoor air doesn’t leak into the home.
There are universal makeup air systems on the market that uses a sensor to open the damper if it detects the range hood turned on. These systems only need low voltage wiring and they work well with new construction or existing kitchen hoods.
Read Also >>What Are The Building Codes For Bathroom Fan Venting?
4. Duct Length
The code requirements for the duct length of range hoods is based on the duct diameter, whether it is smooth walled, and it’s CFM rating.
For example, if your range hood is rated at 200-cfm, and the flex duct has a 6-inch diameter, then the maximum duct length is 18-feet. And a 5-inch diametersizedduct or below isn’t even permitted with a 200-cfm hood and 6-inch flex duct.
The exception to this section is if the range hood satisfies the requirements of the manufacturer or if you independently test the air flow of the hood with some type of measuring device.
The X marks in the table provided below means that under these conditions a duct is not allowed because of the high pressure drop.
5. Exterior Cover
Range hood vents should always be located on the outside and they need to terminate at least 3-feet away from windows, doors, and other vents such as bathroom fans.
If you have a powered air intake such as from a high efficiency furnace, then the range hood vent needs to be at least 10-feet away. The exception to the 10-foot rule is if the range hood vent is at least 3-feetabovethe intake vent.
6. Minimum Exhaust Rate Or CFM
The absolute minimum CFM for a kitchen range hood is 100-cfm.
CFM stands forcubic feet per minuteand it is a range hood rating for how much air the hood can exhaust every 60-seconds. Most range hoods are in the 150-350 cfm range.
7. Must Use Individual Or Dedicated Branch Circuit
Range hoods need to be supplied by an individual branch circuit.
For higher powered range hoods, a dedicated circuit will be needed.
The minimum cord length will be 18-inches and the maximum cord length is 48-inches.
Read Also >> What Are The Building Codes For Dryer Vent Installations?
Makeup Air Venting Code Prevents Carbon Monoxide Poisoning
The main reason for the makeup air code requirement (code #3 above) for some range hoods is to prevent a carbon monoxide hazard.
If you have a very strong range hood, it will create a largeair pressureimbalance in the home (negative air pressure) which can possibly create a backdrafting scenario.
Backdraftingis when negative air pressure actually reverses the flow of the exhaust gases into the home. If exhaust gases are going into the home rather than to the exterior, carbon monoxide poisoning can occur.
Makeup Air Should Go Into Kitchen
If you need a makeup air system by code, the ‘makeup’ or fresh air needs to be sent into the kitchen or room where the range hood is located.
The exception to this rule is that it can go into a different room as long as they are connected by a permanent opening.
The type of damper for the makeup air system should work either by gravity (opens and closed based on air flow) or it can be electronically operated. The electric dampers open automatically when the range hood is turned on.
Read Also >> What Are The Building Codes For Gas Water Heater Venting?
The biggest takeaway for range hood code requirements is that they need to vent to the outside. They can’t vent into a crawlspace or an attic.
Also, there are duct requirements for safety such as the length and the type of material used. If you use too small diameter of a duct, it can cause a pressure drop, and create a hazardous situation.
Another important code requirement is for makeup air.
If your range hood is 400-cfm or greater, you may need to install a makeup air system to prevent a dangerousbackdraftingsituation with carbon monoxide poisoning if you have fuel-burning appliances.
What is code for a range hood? ›
Although the international CFM code for range hoods is 100CFM, some local authorities allow for range hoods with slightly lower or higher CFM than this, depending on the type of your cooking, and the square footage of your cooktop.Is it against code to not have a range hood? ›
Most residential building codes do not require a range hood above a cooking surface, but is that enough to forego having one installed? Even though it may not be legally required for your build or remodel, it is a good idea to install one.Are you required to have a hood vent over your stove? ›
Though you may not be required to install a hood over your stove, it is generally recommended for the best cooking experience. Without one, smoke and fumes may build up in your kitchen. Range hoods also help to reduce heat and moisture while cooking so you may not even break a sweat when cooking dinner for your family.Is there a code for range hood height? ›
In most states in the USA, the average height from the top of the cooking range to the bottom of the range hood is 18”, and it is the minimum height clearance required by most building codes.What is the HVAC code for range hood? ›
A range hood must move at least 100 CFM intermittently, or 25 CFM continuously. The code further states: “Range hoods shall discharge to the outdoors through a duct.What makes a range hood ADA compliant? ›
To comply, The Department of Justice ADA standards section 309 states the range hood control must be placed within reach and shall be operable with one hand and shall not require tight grasping, pinching, or twisting of the wrist Also, range hoods are typically installed 24-30” above a cooktop or 60-66” above the floor ...Are ductless range hoods legal? ›
Some areas may not allow for ducted range hood installation. Apartments often allow ductless hoods only because there's no room for ductwork. Most residential homes allow ducted range hoods.What is code for venting a gas stove? ›
There's no national code for gas venting in the United States. Generally, in the U.S., you don't have to vent a residential gas range to the outside. But, we recommend that you buy a range hood to vent contaminants from your gas range to outside your home.Do I need a vent over my electric stove? ›
The truth is that you should consider a vent for your electric stove. Even if you cook one or two times a week, a vent hood can be beneficial for you. It will clean your indoor air and improve your indoor air quality. For electric stoves, we recommend a range hood of at least 600 CFM.What is the minimum distance between cooktop and rangehood? ›
|Product||Minimum clearance rate specified by manufacturer||Clearance rate to be used by practitioner|
|Gas cooking appliance||600mm||650mm|
How high should a range hood be from the floor? ›
The bottom of the hood should never be more than 72” (182.9 cm) above the floor or more than 36” (91.4 cm) above the countertop. These dimensions provide for safe and efficient operation of the hood.How high should a hood fan be above a gas stove? ›
In general, most installations require a distance from 20" to 24" between the bottom of the hood and the cooking surface. Over a gas range, this distance should be between 24" and 30", unless otherwise specified.What is the NFPA requirement for kitchen hood? ›
If the inspection shows evidence of a build up of greater than 50 microns of grease-laden vapors in the kitchen hood, the hood system must be cleaned. The system, according to NFPA 96 includes the kitchen hood, filters, fans, fire suppression system, light covers, ducts, grease removal devices, and any metal surfaces.Are range hoods required for gas stoves? ›
Unfortunately, many people are unaware of this and it might be because a gas range doesn't have to be vented. Across the United States, the majority of residential homes cooking with gas do not need to vent their range. However, just because you don't have to does not mean that you shouldn't.What kitchen equipment requires a hood? ›
Mechanical ventilation hood systems are required above all high-temperature dishwashing machines (except under-counter models) and cooking equipment, including ranges, griddles, broilers, steam jacketed kettles, ovens, large popcorn machines, deep fryers, barbecues, rotisseries, and any equipment that produces cooking ...What are the venting options for range hoods? ›
There are two types of range hood ventilation systems: external venting and recirculating venting. A convertible range hood can convert from one to another depending on the ductwork that is or isn't present in your kitchen.What is the exhaust vent termination clearance requirements? ›
A mechanical draft venting system shall terminate at least 3 feet (914 mm) above any forced-air inlet located within 10 feet (3048 mm).What is the minimum duct size for a range hood? ›
The minimum allowed duct size is 3¼" x 10", or 6" diameter for round ducts. Never use a plastic duct or one that is smaller than the size specified for the hood as this will directly affect the hood's performance. High performance hoods require larger, up to 10" diameter ducts.What are ADA requirements for ranges? ›
What is an ADA compliant range or cooktop? An ADA compliant range must have controls between 15” and 48” off the ground. This ensures that people can reach the controls easily. People must also have room under the appliance for their legs: 25 inches for their feet and knees.What are ADA requirements for cooktops? ›
ADA compliant cooktops have a few requirements. The controls must be on the front of the cooktop, or at least somewhere which does not require reaching to the back to reduce the risk of burns. Low forward reaches must be no less than 15 in., and high forward reaches must be no greater than 48 in. on the cooktop.
Does a range hood need to be AFCI protected? ›
Yes, this needs to be on an AFCI
All 15A and 20A, 120V kitchen outlets (not just receptacles, but lighting and fixed appliances too) have been required to be AFCI protected since the 2014 NEC. (See 210.12(A) for the details -- it covers just about any sort of space you'll find within a dwelling unit proper.)
Because ductless range hoods are not connected to a duct, they cannot ventilate smoke out of your home. However, they do help remove smoke from your cooking environment by taking smoke in, filtering it, then recirculating the filtered air throughout your kitchen.Is ductless range hood better than ducted? ›
When it comes to power, efficiency, and longevity, ducted hoods are better than ductless hoods. A ductless hood does not completely remove the cooking odors, smoke, and grease from your kitchen air. Instead it recirculates back into your home. But a ducted hood will move all the smoke and odors to the outside.Can you use flex duct for range hood? ›
No, do not use flex duct for your range hood. Most flex duct is made of cheap materials and will not last nearly as long as semi-rigid or rigid duct. You run the risk of having to clean or replace your duct which is quite expensive.What is the maximum duct length for a range hood? ›
For optimum performance, make sure that the air duct is short and straight, with a maximum length of 50 linear feet. Long radius elbows are preferred to short radius elbows for better air intake. Note: Each elbow is equivalent to 10 linear feet of duct.Can a hood vent pipe have an elbow? ›
Yes, you can use an elbow in your ductwork to install your range hood. We recommend using no more than two elbows in your entire duct run. Otherwise, resistance builds up in the duct, causing turbulence. If you need to use an elbow, make sure it is at least 18 inches from the connection to the range hood.Should a range hood go all the way to the ceiling? ›
Absolutely. A range hood extending down from the ceiling creates the illusion of extra height in a kitchen by drawing the eye upward. Its large surface area also leaves plenty of room to play with textures, multi-tonal designs, and accessories like picture frames and wreaths.What is the NFPA code for kitchen hoods? ›
Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations. NFPA 96 provides preventive and operative fire safety requirements intended to reduce the potential fire hazard of both public and private commercial cooking operations.What is the HS code for kitchen hood? ›
|Hs Code||Description||No of Shipments|
|8414||Air Or Vacuum Pumps, Air Or Other Gas Compres-Sors And Fans; Ventilating Or Recycling Hoods Incorporating A Fan, Whethe|
|84146000||Hoods having a maximum horizontal side not exceeding 120 cm||7|
In general, most installations require a distance from 20" to 24" between the bottom of the hood and the cooking surface. Over a gas range, this distance should be between 24" and 30", unless otherwise specified.
What is the maximum distance for a range hood vent? ›
For optimum performance, make sure that the air duct is short and straight, with a maximum length of 50 linear feet. Long radius elbows are preferred to short radius elbows for better air intake. Note: Each elbow is equivalent to 10 linear feet of duct.What is kitchen ventilation requirements? ›
Requirements. An adequate kitchen ventilation system should: Remove cooking fumes at the source, i.e. as close as possible to the cooking equipment. Remove excess hot air and introduce cool clean air, maintaining a comfortable environment.What is the NFPA standard for ventilation? ›
NFPA 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, provides broad-based preventive and operative fire safety requirements for the design, installation, operation, inspection, and maintenance of commercial kitchens.Are Type 2 hoods required? ›
18-28-507.2 Where required. A Type I or Type II hood shall be installed at or above all commercial food heat-processing appliances. A Type II hood shall be installed above commercial dishwashing machines.What is a Type 2 kitchen hood? ›
Type II hoods shall be installed above all appliances that produce products of combustion and do not produce grease or smoke as a result of the cooking process. For example, Type 2 hoods are used to exhaust the excess heat produced by ovens, pasta cookers and commercial dishwashers.What is a Type 1 and Type 2 kitchen hood? ›
So to break it down as simple as possible – go with a Type 1 Hood for cooking equipment that can lead to grease and grease by-products, and go with a Type 2 Hood for other kitchen appliances and equipment that require removal of heat and moisture.What hood is required for a domestic kitchen range used for commercial cooking? ›
A Type I hood shall be installed at or above all commercial cooking appliances and domestic cooking appliances used for commercial purposes that produce grease vapors.What size hood do I need for a 30 inch range? ›
What size range hood do I need for a 30 inch cooktop? For a 30 inch cooktop, install a range hood that is at least 36” wide indoors and 42” wide outdoors.How close can a range hood be from a window? ›
It is safe to put your range hood in front of a window. Some building codes require that your range hood be placed a few feet away, but this is not common. Grease and grime can build up quickly, so be sure to clean the window consistently.What is the minimum distance between a range and hood? ›
If you have an electric cooktop, range hoods should typically be 20–24 inches above the heat source. For gas cooktops, your range hood should be around 24–30 inches above the stove. Range hoods are a great way to complement your cooktop or range and can help clear the air while you cook.
How far from the floor should a range hood be? ›
The bottom of the hood should never be more than 72” (182.9 cm) above the floor or more than 36” (91.4 cm) above the countertop. These dimensions provide for safe and efficient operation of the hood.