How to Vent a Microwave On an Interior Wall

If you’re thinking of installing an over-the-range vented microwave in your home, you’ll be faced with a more challenging installation process if your microwave is going to be located on an interior wall. This will make it a lot harder for you to install the necessary ductwork to vent the microwave to the outside.

If you want to vent a microwave that is located on an interior wall, you’ll need to connect the microwave to your home’s existing ductwork, if possible. If there’s no ductwork nearby for you to connect to, you’ll have to install a new set of ducts and probably make a new vent hole in your exterior wall.

Venting a microwave on an interior wall is certainly a challenge, but it can be done yourself if you have some experience with working on your home’s ductwork and are comfortable with making a few holes in your walls.

In this article, we’ll be going over everything you need to know about venting a microwave on an interior wall, and we’ll explain how to do this yourself. 

Why Vent a Microwave?

Before we get more into how to vent a microwave on an interior wall, let’s discuss why it may be necessary to have a vented microwave in the first place. 

If you have an over-the-range microwave, you’ll need to have it vented in order to deal with the smoke, moisture, grease, and odors that are generated when cooking on your stovetop.

Without a vented microwave, your kitchen would likely be a lot smellier, it would get smoky and hazy whenever you cooked, the surfaces near your stove will eventually become coated in a layer of grease, and the lingering moisture might eventually damage your cabinetry.

Different Vent Types

Image source: Better homes and gardens

When it comes to how to vent your microwave, you generally have two routes to consider; the externally vented route, or the recirculating route. We’ll only be talking about external venting in this article, but it may help for you to be aware of the differences between these two types of venting. 

An externally vented microwave has a fan built into the underside of the microwave, which is connected to your home’s ductwork. When the fan is on, the smoke, grease, and moisture created by cooking get pulled into the ductwork and vented outside your home. 

Recirculating vents, on the other hand, take in air and pass it over a filter before venting it back into the kitchen. These filters are generally good at removing bits of food particulate from the air but don’t really do much in terms of eliminating heat and moisture from your kitchen.

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Recirculating vents are inferior to external vents in terms of being able to remove heat, smoke, and other bits of particulate from your kitchen, but the upside is that they’re far less expensive to buy and way easier to set up.

Also, unlike externally vented microwaves, you don’t have to commit to having your microwave in the same place forever; you can move it around to wherever it’s most convenient since the microwave isn’t hooked up to any ductwork. 

What You’ll Need to Vent Your Microwave

Before starting this job, you should make sure you have all of the necessary tools gathered. At the very minimum, you’ll need:

  • Drill
  • Hole saw
  • Jigsaw
  • Flashlight
  • Measuring tape

If you’re just connecting your microwave to some existing ductwork, this is probably all you’ll need. However, if you’re going to be installing extra ductwork for your microwave, you’ll need a few more things:

  • Ductwork
  • Outside vent cap
  • Aluminum tape
  • Sheet metal screws

You might also want to get yourself a microwave vent template if you want to make things even easier for yourself. It’s important to make sure that all the cuts and holes you make in your cabinet to install the vent are aligned correctly, and a vent template can help you perform the installation correctly on the first try.

If you’re installing new ductwork, you have to make sure that you’re using ductwork that is the right size for your microwave’s fan. You don’t want to install ductwork that is too narrow, as this can restrict the airflow through the tube, which in turn will put a lot more strain on the fan motor and cause it to wear out more quickly.

Fortunately, for a vented microwave, you most likely don’t need any ductwork wider than 4 inches. The width of the ductwork you’ll need depends on how much air the fan can move, as measured in CFM (cubic feet per minute).

The general rule of thumb is that you’ll want 1 inch of ductwork for every 100 CFM of air that the fan can move. Most microwave vents aren’t capable of more than 300-400 CFM, so 4-inch wide ductwork should be fine for pretty much any vented microwave.

How to Set Up Your Microwave Vent

Now that you’ve gathered the necessary materials and equipment, you can start installing your microwave vent. Since the exact steps you’ll need to take will likely depend on the layout of your home and the type of microwave you have, these instructions will be more general in nature.

With that in mind, let’s get started!

1. Plan Your Modifications

Before you do any physical work, the first step is figuring out whether or not you’ll need to install new ductwork, and if so, what direction this new ductwork is going to take. Ideally, you want to have as little ductwork running from your microwave to the outside vent as possible, since this will help with the airflow within the ducts.

If your microwave is on an interior wall, you’ll most likely have to incorporate a few bends in your ductwork in order to make it line up with an exterior wall. You don’t want to have too many bends in your ductwork, however, as this can also restrict the airflow within the ducts. Straighter is always better when it comes to setting up ductwork.

Try to avoid placing your ductwork in the path of any obstacles like floor joists or studs, as you’ll have to make your ductwork unnecessarily long in order to work around them.

2. Install the Ductwork

You’ll need to install your ductwork before you install your microwave since the microwave will be in the way otherwise. Use the sheet metal screws to put the individual pieces of ductwork together, and then seal the edges with aluminum tape. 

If you need to install a vent cap on an outside wall, make sure the edges are thoroughly sealed with caulking to prevent water from leaking inside. When cutting holes in your drywall or exterior walls in order to make the ductwork fit or install a vent cap, you should take extra care to ensure that the holes aren’t cut too big.

If you cut a hole that’s too small, you can always make it a bit bigger if you need to, but you can’t uncut a hole that you’ve accidentally made too big.

3. Install the Microwave

Once the ductwork is all connected, you can begin installing your microwave. This is where you would use your microwave vent template, if you have one. The template will show you exactly where to drill the holes where the microwave brackets will go.

When the bracket is in place, you can then hook the microwave up to the ductwork and install it on the bracket. You may have to drill a hole in your cabinet for the microwave’s power cord to reach an outlet.

4. Test Your Vent

With everything all set up, it’s time to test out your vent. Turn the exhaust fan on, then go to the vent cap outside the house and observe whether air is coming out of it.

If there’s air flowing steadily out from the vent cap, then everything is likely working as it should. If no air is coming through or you have some other reason to suspect that the vent isn’t quite working right, you may want to get in touch with an HVAC professional and have them take a look.


Before we wrap this article up, let’s take a second to answer some other questions you may have about venting your microwave.  

What’s Better, a Microwave Vent or a Range Hood?

The advantage of microwave vents is that they combine a microwave and an exhaust fan into a single unit, which can free up space in your kitchen. The downside of microwave vents, however, is that they’re not nearly as good at removing heat, smoke, and particulate from your kitchen as range hoods are.

If you do a lot of cooking, you’re probably going to prefer using a range hood, but if you want to save some space in your kitchen then a microwave vent may be the way to go.

Image source: storypiece

How Much Clearance Do I Need Between My Stove and My Microwave?

When installing an over-the-range microwave, you’ll want to keep the microwave at a reasonable distance from the stove to avoid heat damage. The exact clearance required depends on the building codes for the area you live in, so check in with your city’s information services to find this out.

Do Microwave Vents Need Special Maintenance?

Microwave vents do require a bit of extra maintenance compared to regular microwaves. In particular, if your microwave contains a charcoal filter, you should inspect and replace this filter at least once a year.

Your microwave may also come with a grease filter, which doesn’t need to be replaced but will have to be washed every six months or so. Protection Status