So, you’ve got a window air conditioner, but you’re not exactly thrilled about drilling holes into your window frame or walls to install it. I get it. I’ve been there too—whether it’s because you’re renting, don’t have the tools, or just don’t want to damage anything permanently. The good news is, you can install a window air conditioner without drilling. I’ve done it myself, and it’s easier than you might think. You just need a little bit of creativity and the right materials.
Let me walk you through how to get your AC up and running securely, without leaving any holes behind. I’ll share my own experiences and give you the step-by-step guide you need to keep cool without any hassle.
Step 1: Gather Your Materials
Before getting started, you’ll need a few things to make sure your window air conditioner stays securely in place. The first time I did this, I found that having everything ready to go made the process a lot smoother. Here’s what you’ll need:
Materials:
Adjustable window locks or window security bars (to keep the window sash in place)
Weatherstripping or foam insulation (for sealing any gaps)
L-brackets (optional) (to help stabilize the AC unit if needed)
Anti-slip rubber pads or felt pads (to protect the window sill and frame)
Tools:
Measuring tape
Scissors or a utility knife (for cutting foam insulation)
Level (to ensure the AC is sitting straight)
Pro Tip: Make sure your window air conditioner fits the window opening before you start. I once tried to install a unit that was too wide for the window, and it was quite the hassle. Measure twice, install once!
How to Install a Window Air Conditioner Without Drilling
Step 2: Prepare the Window
Start by opening the window and cleaning the window sill. You want a clean surface to work with, so take a moment to wipe away any dirt or dust. When I first installed a window AC, I skipped this step and regretted it—cleaning helps the weatherstripping stick better and creates a more secure fit.
Open the window: Raise the window sash high enough to fit the air conditioner. Make sure there’s enough room to position the AC unit without forcing it.
Apply weatherstripping: Stick foam weatherstripping along the window sill where the AC unit will rest. This will help create a tighter seal and cushion the AC unit, reducing vibrations and keeping out warm air. I found that using a slightly thicker weatherstripping worked well to fill the gaps and keep the AC snug.
Photo Suggestion: Applying foam weatherstripping to the window sill. Photo keyword: adding weatherstripping, window preparation for AC
Step 3: Position the Air Conditioner
This is the part where you’ll actually place the AC unit into the window opening. It helps if you have a second person to hold the window open or assist with lifting, but I’ve done it solo before—it’s definitely doable!
Carefully place the AC on the window sill: Set the air conditioner in the window opening, making sure the unit is centered and the back end is slightly tilted downward (this helps with drainage). Use a level to check that it’s angled correctly; a slight tilt is all you need.
Lower the window sash: Slowly lower the window sash so that it rests securely on top of the air conditioner. The weight of the window sash should help hold the unit in place. If the window sash doesn’t stay down on its own, don’t worry—we’ll secure it in the next step.
Positioning the window AC unit and lowering the window sash onto it.
Step 4: Secure the Window and AC Unit
Now that the AC is sitting in the window, it’s time to make sure everything is stable. You want to secure the window sash so it doesn’t move and ensure the AC unit is properly supported.
Use adjustable window locks or security bars: Attach adjustable window locks to the side of the window frame, just above the sash, to keep the window from sliding up. Another option is to use a window security bar that fits horizontally across the window to hold the sash down. I’ve found this method to be very effective—it keeps the window in place without needing any screws or drilling.
Add L-brackets for extra stability (optional): If you’re concerned about the AC moving, you can place L-brackets on the sides of the unit where it meets the window frame. Use strong adhesive strips to attach them without drilling. This adds an extra layer of security, especially if you have a larger, heavier unit.
Protect the window frame: Place anti-slip rubber pads or felt pads under the AC to help prevent scratches and to cushion the weight of the unit.
When I installed my AC this way, I was pleasantly surprised by how secure it felt. The combination of window locks and anti-slip pads really kept everything in place.
Step 5: Seal Any Gaps for Better Efficiency
To make sure your AC works efficiently, seal any remaining gaps around the unit. You don’t want warm air sneaking in or cool air escaping.
Fill gaps with foam insulation: Use foam strips or insulation panels that come with the air conditioner to fill in the side gaps. Cut them to fit snugly. The first time I skipped this step, I noticed my room wasn’t cooling as well, so it’s definitely worth the few extra minutes.
Add weatherstripping around the window: If there are any small gaps around the window sash or frame, add extra weatherstripping to seal them up. This will keep your room cooler and reduce your energy bills.
Adding foam insulation around the AC unit to seal gaps.
Why Doing It Yourself Is Worth It
Installing a window air conditioner without drilling might sound challenging at first, but trust me, it’s very doable. The first time I did this, I was a bit nervous about whether it would stay secure, but following these steps gave me peace of mind. Plus, there’s a real sense of satisfaction in getting it done yourself without needing to drill holes or make any permanent changes.
You’ll not only avoid damaging your walls or window frame, but you’ll also be able to easily remove the AC when the season changes. It’s a win-win, and you’ll stay cool without breaking a sweat. So, give it a shot—you’ve got this!
