Content of the material
- Determine where you want to vent your range hood
- Cut a hole 1-2 inches larger than your ductwork where you’ll run the duct from your hood
- Calculator: How Many CFM Do You Need?
- Range Hood Height, Surface Area Considerations & More
- #2. Vent To Lower Level
- How to Install Ducts on an Interior Wall
- Determine the Least Obstructed Path to the Outside
- Create Access Points
- Thread the Duct Through
- Connect the Duct to the Range Hood
- Attach the Wall/Roof Cap
- Vent Hood Ducts
- #4. Venting Sideways To Exterior Wall
- Ceiling Drywall Removal
- Is there a cost difference between vented and unvented range hoods?
- Is a vented range hood better than an unvented one?
- Required Tools for this Kitchen Fan Vent Project
Determine where you want to vent your range hood
To vent your range hood on an interior wall, you’ll need to cut a hole in the wall for the ductwork. So, it’s important that you know exactly where you want to vent your range hood before continuing with the installation.
Keep in mind that you can always cut a larger hole if needed. But you can’t put the wall back if you cut a hole that is too large.
You might also be wondering: what size ductwork do I need for my range hood? Check out the chart below.
The larger the range hood’s CFM, the larger diameter duct you’ll need. Otherwise, your duct will choke the air as it moves to the outside. It puts more strain on the motor to vent the same amount of air through a smaller duct compared to a larger duct.
Your hood will not be able to move the amount of air it is advertised to move. For example, a 900 cfm hood attached to ductwork that is less than eight inches will not be able to move 900 cubic feet of air in a minute.
So, if in doubt, go with a larger duct. To learn more about duct size, check out our complete guide.
Cut a hole 1-2 inches larger than your ductwork where you’ll run the duct from your hood
Your hood will be running for years to come, so you want it to comfortably fit in your kitchen.
One to two inches gives you space to thread the ductwork through the hole so you can attach it to the hood with ease.
Calculator: How Many CFM Do You Need?
Range Hood Height, Surface Area Considerations & More
As a general rule, calculate 100 cfm for every linear foot of cooking surface. For pro-style ranges, the formula is 100 cfm for every 10,000 BTUs your appliance puts out. Other factors come into play as well. For every 3 inches a hood exceeds the suggested height above the cooktop, add 100 cfm.
Island hoods require extra cfm to compensate for cross drafts, so calculate 150 cfm per linear foot for conventional cooktops; add an additional 100 cfm to the pro-range estimate. And consider how you cook. If you rarely grill or stir-fry at high heat, you may be able to go with a lower cfm than recommended.
#2. Vent To Lower Level
Another option for homeowners is to install a vent to the exterior by going down a level and then horizontally to the outside.
The only problem with this strategy is that the vent must go in-between the interior wall joists, so the range hood (and oven) need to be exactly centered. If your oven and hood isn’t centered correctly, then they will have to be moved so that the center of the hood lines up with the center joist space.
One great thing about this venting strategy is that you can even install a remote blower in the basement. This means that your range hood will be significantly quieter because the blower fan isn’t at the hood, it is in the basement near the exterior wall.
With a remote venting application, it also frees up the kitchen cabinet space above the hood because there isn’t a blower.
Read Also: How To Paint An Old Range Hood?
How to Install Ducts on an Interior Wall
Determine the Least Obstructed Path to the Outside
Keep in mind the 30-foot rule. You do not want your duct to exceed 30 feet in length. There shouldn’t be more than two elbows in the structure, either. To do this, you must determine the least obstructed path from the range hood to the outside.
You must be very familiar with the inner structure of your house to do this. Ideally, you should select a path with no stud, piping, or electrical wiring.
Create Access Points
To construct your ventilation duct, you must have access to key points along the route of the ducting. This will be much easier if you choose to vent your range hood down into the basement or through the attic to the roof.
However, if you decide to vent through the walls, you may have to cut through them.
If you aren’t sure what is in your walls, do not attempt to cut them yourself. Consult a professional first.
Thread the Duct Through
Depending on your chosen venting option, thread the duct accordingly through the walls to the outside. Use the access points that you cut into the walls to make the job easier.
One part that you have to be careful with is the size of the hole that your ductwork runs through to reach the range hood. To make it easier for the ductwork to connect, make sure that the hole is around 2 inches wider than the diameter of the duct.
Connect the Duct to the Range Hood
Once the construction of the ductwork is complete, it’s time to connect it to the range hood. This step should be fairly easy and will usually be detailed in the user manual for the range hood.
Usually, all you have to do is join the duct together with the transition piece using stainless-steel duct tape.
Attach the Wall/Roof Cap
Head over to the place where the duct ends. If the duct ends on an exterior wall, attach a wall cap.
If it ends up on the roof, use a roof cap.
The cap will help protect the duct from debris and the elements, protecting it from damage and helping it run for longer.
Vent Hood Ducts
When it comes to ductwork, it’s a numbers game.
- Choose ducting that’s the same size as or slightly larger than the vent opening. The more powerful the hood, the larger the duct. For instance, a typical 400-cfm unit requires a 6-inch duct, while a 1,200-cfm model needs a 10- to 12-inch duct.
- For the best airflow, use smooth galvanized metal ducting rather than flexible or corrugated ducting. Seal joints with duct-joint mastic tape.
- Keep duct runs as straight and short as possible. Use gradual, 45-degree turns rather than 90-degree ones. The fewer the turns, the more efficient the system will be.
#4. Venting Sideways To Exterior Wall
The most common vent installation when the hood is on an interior wall is to go horizontally to the exterior.
You basically have two options, you can go through the top of the kitchen cabinets to the exterior, or you can go through the ceiling.
If the ceiling joists aren’t running parallel with the duct run, then you will have to cut holes into the joists. You may or may not be able to cut holes in the joists due to the size of the joist, the type of joist (engineered vs dimensional), and the size of the vent.
Even engineered I-joists have manufacturer limitations on the size of holes that you can cut (and where on the joist). Consulting a knowledgable contractor or engineer, as well as perusing the joist manufacturer manual is highly recommended if you will be cutting joist holes.
If the joists run parallel with the vent duct, then it isn’t a problem, but you will still have to cut the drywall.
Ceiling Drywall Removal
When you remove drywall, you have two options. You can remove the entire drywall section from the hood to the exterior wall. Or you can just cut two holes in the drywall at the duct entrance and near the exterior wall.Either way, you will be cutting into drywall, and the cost of patching will need to be factored into the installation. If you install the duct in the upper kitchen cabinets, you also need to factor in that you will lose that cabinet space.
Is there a cost difference between vented and unvented range hoods?
Prices for range hoods vary anywhere from around $80 to more than $2,000, depending on the size, manufacturer, and design. Many range hoods on the market can be used vented or unvented, so you’ll pay the same except for the added filter or conversion kit.
Is a vented range hood better than an unvented one?
Without question. It’s far preferable to vent the air outdoors than to recirculate it into the room. A vented hood that removes steam, smoke, heat, and cooking odors is the best way to keep your kitchen clean, since it gets rid of grease particles that would otherwise accumulate on your walls and cabinets.
Unvented range hoods do filter some grease and cooking odors from the air, but the general consensus is that they’re nowhere near as effective. Nor do they remove heat and humidity, so they won’t help keep your kitchen cool while you cook.
Required Tools for this Kitchen Fan Vent Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
- Caulk gun
- Cordless drill
- Dust mask
- Extension cord
- Tape measure
- Tin snips
- Utility knife