How to Build a Window Box
Get the curb appeal you've always dreamed of with simple DIY window boxes.
The one thing you need to complete a picture-perfect home exterior is a set of handmade window boxes. Filled with blooming flowers, sweet succulents, or maybe fresh herbs, window boxes are full of possibility. The ones we have here are a classic design that can be modified to fit any window size. With just a few tools, even a beginner carpenter will have in done in no time. Follow along with our steps to make sure the building goes smoothly.
Note: Our window boxes are designed to fit nicely under a 36-inch wide window.
What You Need
- 1" x 8" x 8' cedar board
- 1" x 6" x 6' cedar board
- 1 qt. exterior polyurethane sealer
- 1-5/8" outdoor deck screws
- 120 grit sandpaper
- Miter saw
- Table saw or jigsaw
- 1/8" drill bit for pilot holes
- 1/4" drill bit for drainage holes
- Tape measure
- Outdoor rated wood glue
Step 1: Make Cuts
Cut box bottom, back, and front to length. Cut front to a width of 7" (slightly smaller than the back and sides).
The box sides are cut at an angle to give the front profile of the window boxes more of a custom decorative look. First measure and mark the length for one side, but don't cut yet. It will be easier to hold the board and cut the angle first. Now mark a 15 degree line from the outside edge. Cut this angle first using a jigsaw and a straight edge. Then cut the length with the miter saw. Repeat for second side.
Step 2: Connect Sides
Hold the box front to the angled edge of one box side. Drill pilot holes for three evenly spaced holes and attach with wood glue and deck screws. Repeat with the other box side.
Editor's Tip: Assembling this step with the boards sitting upside-down, like shown above, may give you a sturdier base.
Step 3: Attach Back
Hold the box back to the straight edges of the box sides. Drill three pilot holes and attach with wood glue and deck screws. When you drill, be sure you're holding the drill perpendicular to the board so that the screws don't go in on an angle.
Step 4: Attach Bottom
Turn the window box right-side-up. Set the box bottom into the window box until it is snug and flat. Drill pilot holes, making sure you are lined up with the edge of the box bottom inside. Attach with wood glue and deck screws.
Step 5: Make Drainage Holes and Finish
Drill drainage holes into the bottom. As you drill, keep a scrap piece of wood beneath the box so that you don't drill into your work surface. Finally, sand the window box. Paint, if desired, and finish with exterior polyurethane.