Installing window boxes is a fun DIY project and proper care should be take to do it right! There are many brackets nowadays that hook to your window or railing and allow you to just sit the window box on top. This is fine if your window box is small and you don’t plan on filling it with potting soil. However, if your window box is larger than 30″ and/or it will need to support more weight than just fake flowers, it’s imperative that you install your window boxes in a safe and secure manner so that it doesn’t shift, fall, or break. Decorative window box brackets can be added, but should rarely be used as the goto method for supporting a window box. Most decorative window box brackets are either faux brackets or they are not designed to be structurally secured to the home themselves, but to act as a decorative accent to the window box.
First off, window boxes need to be installed so that they are level. This is important not only so that it looks right, but also that it drains properly. This is another reason to avoid simplistic bracket systems that can bend and warp under the weight of a well planted window box. The ideal method for installing window boxes is to use the old tried and true anchor-lag bolt method. By securing and installing a window box to a home’s exterior in this manner you can ensure that it is level, sturdy, and most importantly safe. And as an added feature, it will most definitely add value to the home by becoming a part of it.
Step one to install a window box is to determine the number and placement of the lag bolts. Next, drill a 3/4″ hole in the back of the window box evenly spaced and approximately every 18-24″ of window box length. Then, hold the window box up to the window and with a pencil trace through the predrilled holes onto the house the location of the holes. Now take the window box down. Using a hammer drill with a masonary drill bit, drill a 5/8″ hole into the brick or rock for each mark you made on the house. These are going to be your anchor points to support the box (if you are installing on siding or stucco you will need to hit studs and the size and placement of these may differ). Next, place a 5/8″ expandable lead anchor into the holes you drilled. This anchor should be able to receive a 3/8″ lag bolt (if you are installing on siding or stucco, a lead anchor is not necessary. Drill a 1/4″ hole and pass the lag bolt directly into the hole such that you hit a stud). Now, to finish installing your window boxes, hold the window box back up and pass a lag bolt with a heavy duty washer on the end through the back of the window box and into the predrilled hole/anchor. Tighten each lag bolt down till finished and then lastly, use a level to adjust the window box if necessary. That’s it! You’re done installing window boxes.
