How to Vent a Microwave on an Interior Wall
What to know

How to Vent a Microwave on an Interior Wall?

A microwave can either by self-vented (ductless) or externally vented by ducts (ducted). Regardless, when it comes to venting a microwave on an interior wall, you need to essentially find a way to put up ductwork for it with existing ductwork or a newly installed one. Or get a contractor to do it for you.

How to vent a microwave?. The key is in the ductwork and how your microwave connects to it, though.

How to Vent a Microwave on an Interior Wall?

In order to vent a built-in microwave on an interior wall, you need to you should access your existing ductwork to allow the hot air produced inside the device to exit your home in a safe manner.

You essentially need to prepare the space, cut the power, install the ductwork, prepare the new vent, and test the vent. Yes, a vent needs to be installed or modified in order to vent your microwave on an interior wall. There are no two ways about it.

to vent a built-in microwave
To vent a built-in microwave

Tools and Materials Needed

The tools you’ll need include a flashlight, measuring tape, jigsaw, drill, hole saw, and varying sizes of drill bits. The materials you’ll need is the vent, sheet metal screws, metallic adhesive or duct tape, and ductwork.

Depending on the configuration of your home, you might need to install new ducts or modify ductwork that’s already there. Otherwise, don’t put your microwave on an interior wall and get a freestanding microwave that can self-vent.

Prepare the Space and Cut the Power

Examine the current ductwork. Make up your mind regarding which path the vented air should travel. To find the path of least resistance, go with the most direct and straightest way for the vented air and moisture to reach outside.

Once you’re aware of your microwave placement, get a template to mark where the bracket and holes should go. Turn off the power to the circuit connected to the kitchen and microwave. Don’t plug in your microwave just yet.

Ductwork Installation

If you need to build or modify new ductwork in order for proper microwave ventilation to happen, do this before putting in your built-in on your cabinetry or interior wall. Install both the ductwork and the required vent cap beforehand.

Make sure to piece together the ductwork pieces with sheet metal screws. Afterwards, use metallic or duct tap in order to secure the seams to ensure a secure and tight fit when push comes to shove.

If you’re venting through the roof, make sure to use sealant or caulk to seal the edges of the vent. Also check if the shingles are firmly connected around the vent exit. This process safeguards your vent from moisture accumulation and leakages from entering your roof, which damages it.

You may also like: How to Tell If Your Microwave is Vented Outside?

Install Your Microwave and Prepare Your Vent

After installing the proper ductwork in case you’re lacking one directly available to your built-in, it’s now time to drill the bracket holes using the template. Afterwards install or mount your microwave. Drill a hole on the bottom of your upper cabinet. This is the space where your power cord should go.

You need to turn the exhaust of your microwave to 90° in order to redirect the air it’s releasing into the vent. Otherwise, you need an exhaust adapter to suck in that microwave hot air into the exhaust. This adapter might also require pieces to fit the round microwave exhaust into square ducts.

The adapter prevents forcing the round peg of the microwave exhaust into the square hole of the ductwork, in a manner of speaking.

You can see more in this video to vent to the exterior wall.

Test Your Vent to Make Sure It’s Working

Once the microwave is installed and connected to the existing or newly built exhaust, it’s time to test vent effectiveness. Plug in and turn on the microwave. Put a glass of water inside the unit for a trial run on how well the exhaust connection works.

Microwave the cup to test if the air is venting correctly, delivering the exhaust air to the outside instead of all over your kitchen. Don’t turn the microwave empty. This can damage the appliance. Put a glass or mug of water inside there, at least.

Why is Ventilation Essential for a Microwave?

Even a freestanding microwave requires a measure of self-ventilation to work in your kitchen, which should then have a hood vent or ductwork to keep it from becoming too hot or toxic inside there. Microwaves assist in helping heating your leftovers or preparing quick snacks.

Microwave rays generate a huge amount of moisture of heat due to how they specifically react to the water content and molecules of your food. Quite a number of OTR microwaves positioned over your cooktop simply have a blower that assists in recirculation of this accumulated humidity and heat.

Removing the Moisture and Heat Inside the House

A microwave blower and self-venting might not be enough to direct the moisture and heat away from your kitchen and out of your home. Many kitchens have doors leading outside for easy ventilation. Or they’re in an outdoor location with no walls.

However, for indoor kitchens, ventilation is a must to get all that heat, particulates, and moisture out of the enclosed room. Ventilation and ductwork also help in getting rid of the smalls and odors produced while cooking something in your microwave.

Mold and Mildew Can Develop from an Enclosed Humid Environment

Too much heat and humidity can result in your walls, floor, and kitchen paraphernalia getting mold and mildew. It’s like leaving your car in the rain without airing it out afterwards. The musty mold can also damage the wood fibers of your cabinets for good measure.

A microwave that isn’t vented properly or relies on recirculation of exhaust fumes can damage your home and kitchen as well as itself.

Keep in Mind the Following

A microwave with poor ventilation can end up damaged over time. Even a freestanding countertop microwave requires a recirculating vent system to work, with the ducts or hood range of your kitchen handling the resulting exhaust of steam, heat, and particulates.

When moisture or humidity is allowed to collect inside the kitchen, it tends to penetrate through walls and cabinetry. This is why in lieu of a vent for your non-self-venting microwave, you need to connect it to existing ductwork or install a vent for it.


  1. Can You Put a Microwave in a Cabinet?“,, Retrieved August 18, 2021
  2. How To Vent A Microwave On An Interior Wall (Do This!)“,, Retrieved August 19, 2021


Through the years, the microwave oven has become a standard appliance for all homes. It is safe to say that there is no home without a microwave oven. If you are looking for a microwave oven that best fits your needs, You find the right website.

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