How To Install Window AC Unit Without Side Panels (DIY)

Installing a window AC unit is an easy and economical way to cool a room or a small house. Most manufacturers provide side panels to help seal the unit in place.

But those side panels are not always included, or they do not work. But there are quite a few options on how to install window AC units without side panels.

Can I Install A Window AC Without Side Panels?

Window AC side panels are AC unit extensions that help a room maintain an airtight seal. Their purpose is to seal the ways that air can enter and leave the room. They are typically made of accordion-shaped plastic.

A window AC side panel can stop hot air from the outside from coming in and keep the cool air that you want to circulate in your room or space from seeping out.

Side panels also prevent creatures like small animals and insects from infiltrating through the small spaces between your window and the AC unit.

You can install a Window AC without side panels, and people do this for various reasons. Sometimes, the window is too large to accommodate side panels, or someone doesn’t like how they look.

If you want to install a window AC unit without side panels, you can use foam insulation, duct tape, plexiglass, or plywood to create an airtight seal.

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Install Window AC Without Side Panels

How To Install Window AC Units Without Side Panels

Window AC units will usually come with a side panel extension included. They are made of plastic and are accordion-shaped to help fit the size of your window. But there could be several reasons that you can not use them.

  • They may be damaged or missing if you bought a used unit.
  • They might not fit your window well enough to be trusted to create a seal.
  • You might not like the way they look. After all, they are usually thin, and they are not optimal for preventing leakage of your cold air and keeping insects out of your house.

You do not have to use the window AC side panels included with the unit. There are quite a few options for you to create your own. You can DIY window unit AC side panel alternatives out of materials like foam board, plexiglass, or plywood. Some of the options that you have to choose from are:

Using Foam board insulation

One of the least expensive ways to create side panel alternatives for your window AC unit while still being effective is to use foam board insulation at your local hardware or home goods store. It is easy to cut and shape your window. And it will be easy to replace if it becomes damaged or you want to uninstall the unit.

Tools needed:
  • Cutting Implement: Scissors, knife, or foam cutter
  • Adhesive: glue, duct tape, or caulk
To install:
  1. Prepare the area by cleaning dust or debris
  2. Measure the window opening left by your AC unit
  3. Cut the foam board to your measurements
  4. Attach using an adhesive
  5. Use duct tape on the seams to create an airtight seal

Using Plexiglass

Plexiglass may be a better option if you want to let in the most natural light possible. It is also great for energy efficiency. However, installing it may be more time-consuming and will cost a little more.

It may not be as effective as foam board at insulation, but plexiglass has a higher thermal value than the glass it is replacing. If you are cooling a room or a small house, it should accomplish the job quite well.

Tools needed:
  • Cutting Implement: Power saw
To install:
  1. Clean area of dust or debris
  2. Take out the window panel
  3. Cut plexiglass to the same size as window panel
  4. Cut additional space for your AC unit
  5. Attach the plexiglass where your window panel used to be
  6. Install AC Unit to plexiglass

Using Plywood

Using plywood to create side panel alternatives for your window AC unit should be your last option.

It is not the most effective. Foam board insulation and plexiglass offer a better barrier than plywood. It is not the cheapest, and it can look unattractive.

Tools needed:
  • Cutting Implement: Power saw
  • Screw installation: Power drill
  • Wood Treatment: Wood treatment formulae such as spray-on paint, epoxy sealant, or polyurethane varnish
To install:
  1. Clean area of clutter or debris
  2. Take out the window panel
  3. Cut plywood to fit window panel
  4. Measure the air conditioner
  5. Cut the whole in plywood to fit the air conditioner.
  6. Attach plywood to the window frame by using screws
  7. Slide the air conditioner into the opening and screw it in.
  8. Treat the plywood for waterproofing.

How To Replace Window Air Conditioner Side Panels?

To install foam board insulation, you first must measure the window and AC unit. Cut the board to fit snuggly around the window AC unit and paint it. Push it firmly in place, but not so hard as to break it.

To install the plexiglass, cut and shape it with your window measurements using a glass cutter or a box knife. Slide it into place and secure it with screws in all four corners.

Depending on your unit’s size and window, you could add screws at the top and bottom. Then, you can create a decent seal around it using weather stripping tape or caulk. Just be sure that there are no gaps.

You install plywood in much the same way as plexiglass. Cut it to shape, secure it with screws, and seal with weather stripping tape or caulk. Cutting it is different in that you will need a saw, and you will have to do it outside because there will be a lot of sawdust.

If you take your measurements with you to the hardware store, they may be able to cut them for you.

Related ArticleShould a Window AC Be Tilted?

Replace Window AC Side Panel

People Also Ask (FAQ)

Here are the frequently asked questions pertaining to installing window AC without side panels.

How do I fill the gap around my window air conditioner?

A window AC unit is designed to go in any window. But, there are a lot of differences in window sizes.

After you follow the steps in this article to create the side panels, you can use weatherstripping tape to fill all of the gaps around the unit. You can find that at your local hardware store. Another method is to caulk around it. To get the most effectiveness, you could do both.

Will the window AC unit work correctly if you do not fill the gaps?

If you do not fill the gaps around your AC unit, you will let the cold air you are creating leak out of your house, and hot air from outside will come in. In addition, you are leaving your window wide open to ants, bees, spiders, and other creatures that might seek refuge in your home.

Related Article How Does a Window AC Work?

Can you install the window AC unit without the screws?

Yes, you can. Look for an additional article from us that will address this more in-depth.


There are several ways to create side panels for your window AC unit if you do not use the ones that it comes with. Plexiglass will be the most eye-appealing since it will let in natural light. If you are more interested in being energy efficient, you may choose foam board insulation.

Regardless of your goal, there are plenty of options available that will be easy on your wallet and are easy to implement and maintain.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.