How to Attach a Window Box to Siding

January 31, 2021

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Fun fact: when I originally wrote this post in 2018, I had VERY LITTLE of anything DIY-related figured out. I thought that maybe the rest of the world already knew how to attach a window box to siding and would think I was stupid for writing this. But since Google hadn’t helped me when I searched, I wrote this anyway.

And then, this ended up being my MOST POPULAR BLOG POST in 2019! So it’s safe to say that there are lots of other people confused about their window box installation.

The Problem with Installing Window Boxes on Siding

When I was researching how to attach the window boxes that I had just built, all I could find were advertisements for vinyl siding hooks. Obviously, plastic siding hooks were not going to do this job correctly.

In fact, everything that showed up was an advertisement for a way to attach things to vinyl siding without drilling holes. However, it was more for hanging wreaths or flowers–definitely not for attaching something as heavy as a window box.

So, it made me wonder. Why is everyone so anti-drill for siding?

After way too much time typing variations of the phrase “Am I a terrible person if I drill into my siding?” into Google… I came to a decision.

Is it okay to drill into your vinyl siding?

The verdict is, you can.

HOWEVER, there is a small risk of water getting behind your siding. THAT’S basically the reason why you shouldn’t drill hundreds of holes into the exterior of your house.

But the risk of water getting behind your siding and actually causing a serious issue is very, very tiny. If you decide at any point to remove your window boxes, you can easily patch these holes.

So now that we all feel good about it, let’s finally see how we attach window boxes to siding–the right way.

Supplies to Attach Your Window Box to Vinyl Siding

(P.S. Those links go to Home Depot because they offer same-day pickup. Let’s get this done.)

It’s very possible that you already know what the steps are going to be now that you’ve seen the supply list. 

The hero of this simple installation is the L-bracket (also called a corner brace). Since your window box is going to be pretty heavy with the soil, plants, and water, you’ll want to get the largest size brackets that you can.

And if you discover the amazing power of L-brackets/corner braces, you can use them to make some other super cool projects like fake floating shelves or a rectangle shelf.

Step 1: Hang L-Bracket on Siding

Get your bracket and choose where you want your window box to sit. Then, use your drill bit to drill a pilot hole through the hole in the bracket, through the siding, and into the wood behind it.

Then use your drill to screw the wood screws into the holes to hold the bracket up.

Of course, I don’t have a picture of this because it was 2018 and I was quite literally juggling two kids under two–and not all that well. But here’s a picture from HGTV that shows you what this will look like.

L-bracket to attach window box to siding

It almost looks like they painted their bracket and screw, but this is completely unnecessary because you won’t ever actually see the bracket.

Also, make sure that both of your brackets are even by using a level.

Step 2: Attach Window Box to the Brackets

Now, put your window box on top of the brackets. You’re going to do the same thing you just did–drill pilot holes through your bracket and into the bottom of your box.

Then, drill your screws into the holes spot. You’ll feel the box tighten.

Bracket used to attach window box to siding
Bracket used to attach window box to vinyl siding

Oh, the irony. Now that it’s 2021, three years of DIY practice after this original post, and I am just realizing that I don’t think I used the right screws for this project.

So don’t use this image above as an example of which screws to get. Make sure your screw heads don’t go THROUGH the holes in your steel bracket. You’ll probably want to look for #10 or #12 screws.

Step 3: Fill Your Window Box and Admire Your Work

Yes, that is seriously how easy it is to install a window box to vinyl siding!

Attaching these window boxes was the final step in my curb appeal overhaul, after I had painted and attached shutters, and attached this creative solution to my weird & ugly siding. 

Do you want to keep your window box pretty and festive, even in the Fall? Check out 11 ideas to decorate your window box for the Fall?

There are so many other ways to easily transform your home into a place that you LOVE. Just stick your email in this blue box below to get my free Love Your Home email course.

Window box on siding
Window box on siding
Window box on siding


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Hi! I’m Kaylee–a mom of 2, business owner, DIY addict, and so much more. You’ll find some fun DIY tutorials, totally honest reviews, and lots of tips for making your home fit YOU. Welcome to Mama and More!