How to Vent a Range Hood through the Roof or a Side Wall

How to Vent a Range Hood through the Roof or a Side Wall

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Vent Hood Parts

Illustration by Stephen Rountree
  • Sump: Inverted area along the rim that collects fumes until the fan can exhaust them. Should be at least 1 inch deep.
  • Filter: Traps grease before it can reach the blower and ductwork. Metal mesh filters are the most common type.
  • Blower: Also called a fan, it moves air into the duct. Most blowers are in the hood, but they can be located “in-line,” up in the duct itself, or externally (inset), where the duct terminates.
  • Ductwork: The metal channel that leads the air out to the exhaust vent.
  • Damper: Prevents outside air from coming in when the fan is off.

Note: Vent hoods over 400 cfm require that makeup air be brought in from the outside when the unit is on. This air can come from a supply fan, a motorized damper, or another source.


Best Practices When Installing Range Hood Ductwork

1. Do not terminate the vent system into an attic, or another enclosed area. 

If you follow any tip in this list, follow this one. It is vital that you vent your hood outside your home, through the ceiling or wall.

It’s not healthy for smoke, cooking exhaust, humidity, and contaminants to build up in your attic. Instead, run the duct all the way to the outside. This way, you’ll get rid of the smoke and cooking exhaust for good.

The best option is to vent vertically through the roof if possible, since hot air rises. But this is not required. Vent through a side wall if you cannot vent directly above your hood.

To have a smooth installation, find a great contractor to install your ductwork.

2. Do not use more than two elbows in your ductwork. The fewer elbows, the better

Each elbow adds some resistance to your duct system, which makes it harder for air to make it to the outside.

A couple of elbows are OK; you might need them just to navigate through your walls. But don’t use more than two to keep your hood running as efficiently as possible.

When adding elbows to your duct, keep the following in mind:

  • For each elbow in your duct, reduce the total length of your duct run by 5’. For example, a 30’ straight run is about equivalent to a 20’ run with two elbows.
  • When installing your duct, include at least 18″ of straight run before adding an elbow.
  • Make sure there is at least 24″ of straight duct between each elbow.

3. Install your ductwork in the shortest unobstructed path to the outside of your home

When possible, orient your ductwork so that you use the shortest run possible with the fewest elbows. This way, the unwanted air encounters the least amount of resistance and vents out of your home with ease.

Ignoring aesthetics, the shortest and straightest run of ductwork is the best for the power, efficiency, and longevity of your vent hood.

Do not use more than 30’ of ductwork. The longer your duct, the more resistance it has.

If your duct is longer than 30’, the air will really struggle to make it to the outside, even with a powerful range hood.

4. Use rigid galvanized steel or metal HVAC ducting only. Do not use plastic flexible duct

A range hood should last you 10+ years, but flex duct simply won’t hold up that long. Rigid duct is much more durable. It’s your best option.

Rigid duct systems will also encounter less air resistance than flex duct systems, so all the greasy kitchen air will move smoothly to the outside.

Make sure that you use the appropriate sized duct to keep your duct system efficient. Duct size depends on the CFM of your range hood.

For example, if you have a 900 CFM hood, do not re

For example, if you have a 900 CFM hood, do not reduce the diameter of your duct below 8”. See the graphic below.

Once you’ve installed the appropriate duct, seal it to your hood using aluminum tape.

5. Seal the end of your duct run with a wall or roof cap

A cap keeps dirt and debris out of your duct. It also prevents backdrafting, which is when outside air moves into your duct.

Then, use caulking to seal exterior openings around the cap.

This keeps the cap secure and prevents greasy kitchen air from leaking out the edges of your duct system.

#3. Venting Through Attic

Venting through an attic is also a common way to vent exhaust fans.

For this installation, the attic will need to be the next level above the kitchen, so you can go through the kitchen ceiling, through the attic and then to the roof or gable wall.

If it is installed on the roof, a special roof cover (preferably steel) will need to be installed. You can’t just use a normal wall vent cover on the roof, it needs to be designed for a roof installation.

Also, since the vent is going through the attic, there is the potential of condensation forming on the vent. You can lower this risk by insulating the ductwork inside of the attic.

Read Also: What Are The Best Rated Downdraft Range Hoods?

What Does an Internal Blower Do?

Before we get into the benefits of internal vs. external venting, let’s take a look into what range hoods actually do. A range hood is installed above the range or cooktop in your kitchen. When in use, this handy appliance uses a blower to pull air from the area and cycle fresher air back into your kitchen. As a result, you are able to remove excessive heat, steam, smoke, cooking odors, and fumes from your kitchen to provide a cleaner, safer, and overall more comfortable environment. A range hood can be particularly useful to cool down the surrounding area and filter out smoke or steam while you cook. It can also be used to remove odors and fumes from your kitchen, such as when you are using a self-cleaning cycle in your oven.

Noise Reduction Solutions

Illustration by Jason Schneider

Worried that a powerful vent hood’s overly loud whir will make it impossible to carry on a conversation while you cook? Although most blowers are in the hood, they can also be placed in different locations to help reduce the noise. You just need to specify where you want it before you order the hood.

In-line blowers are located in the ductwork in the wall or between the ceiling joists. But while the fan noise may be less noticeable, you still might hear the duct vibrating.

A better option is a remote or external blower, where the fan is placed on the roof or exterior wall with the exhaust vent. Placing the blower outside can also free up cabinet space.

What are the different venting options?

Now that you know the step-by-step procedures on how to vent a range hood on an interior wall, it would be easier to choose the best method to do it.

Here are other options:

Vent to a lower level This option means you have to go down a level, then go horizontally to the outside. The vent needs to go in-between your interior wall joints to allow the range hood as well as your oven to be centered accurately. If they are not properly centered, you have to move them to allow the hood to align with the central joist space.

The advantage of this venting technique is you can install a remote blower in your basement, eliminating the sounds from your range hood. This is because the blower fan will be near the exterior wall.

Venting sideways to exterior wall This method gives you the option to go through the ceiling or the top of your kitchen cabinets to the outside. If the joists run parallel with the duct, it will be easier to vent your range hood. You only need to make a hole in the drywall. However, you need to cut holes into the ceiling joists if they do not run parallel with the duct run. The type and size of the joists and the vent’s size would determine if you can cut holes or not. Before cutting, you need to consult an engineer or contractor about this matter.

What materials do you need to vent your range hood on the interior wall?

Here’s a checklist of tools and supplies to ensure

Here’s a checklist of tools and supplies to ensure seamless and successful venting:

  • Manual on how to vent a range hood on an interior wall
  • Level
  • Measuring tape
  • Pencil
  • Utility knife
  • Adjustable wrench
  • Screwdriver
  • Self-tapping screws
  • Aluminum or duct tape
  • An angle grinder, PVC trim, and silicone (for creating a mounting plate)
  • Ductwork
  • Wall cap
  • Hole saw
  • Needle nose pliers
  • Electric drill
  • Clear exterior caulk
  • Safety gloves and goggles

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How to Install a Range Hood Vent Through the Ceiling

Check out the full step-by-step guide here.

We hope this information on range hood venting options as well as ducted and ductless range hoods has been helpful for you. Thanks for reading!


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