This project was built and designed by John from John Builds It. He created a clean and elegant solution for finishing window tops using simple tools and pre-primed pine boards.
The cornice boxes are designed to hide curtain rods and add visual interest to a room. It’s a great project for woodworkers looking to tackle something quick but impactful.
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Why Try Cornice Boxes?
Cornice boxes add a polished look to your windows by concealing hardware and giving the room a more finished appearance. They’re versatile in design and can be adapted to match traditional, modern, or rustic styles.
This project offers a lot of visual value with minimal complexity. It’s an approachable upgrade for any space with standard windows and existing curtain rods.
Materials and Planning
John used pre-primed pine for this build, balancing affordability and ease of painting. Despite some hesitation about using factory-coated wood, the cost savings made it a smart choice.
When choosing materials, it’s important to consider both your budget and the look you want to achieve. Pre-primed wood is especially helpful for painted finishes, reducing prep time.
Cutting and Setup
Before cutting, John adjusted his shop setup to handle longer boards safely. By removing part of his miter saw dust hood, he created more room to support the pine during bevel cuts.
A miter saw was used for precise angles, helping ensure each joint was clean and square. Good setup and planning made it easy to move through this stage quickly.
Assembly and Joinery
To join the frame, John used painter’s tape to align the pieces before applying glue and brad nails. This technique allowed for precise assembly and kept everything held in place during the glue-up.
Since the boxes were going to be painted, small gaps or surface blemishes weren’t a concern. They were later filled and smoothed for a clean, uniform surface.
Adding the Top Panel
The top panel of each cornice box serves both functional and aesthetic roles. It adds structure, blocks light from above, and provides an anchor for mounting.
John secured this piece with screws, creating a solid and durable frame. With the top in place, he moved on to filling and sanding the seams.
Decorative Trim and Crown
To tie the cornice box into the existing baseboards, John chose a base cap molding. This helped the box blend in with the rest of the room’s trim and added depth to the overall look.
After cutting and attaching the trim pieces, he used pin nails to secure the corners. Crown molding was added last to give the boxes a taller, more refined appearance.
John also shared a tip for cutting crown molding flat on the saw instead of adjusting the bevel. This technique simplifies the process and reduces the chance of miscuts.
Surface Prep and Painting
Once assembly was complete, John filled the nail holes and sanded all surfaces smooth. A primer was applied using a quality surfacer, which improved paint adhesion and coverage.
He finished the boxes with Sherwin-Williams Emerald paint, applied with a sprayer for a smooth, professional result. The Graco Magnum X5 made quick work of the finish coat and delivered consistent coverage.
Mounting to the Wall
After the paint dried, it was time to install the boxes. John kept the width minimal to avoid interfering with existing curtain rods.
He marked the ceiling and used a stud finder to locate secure mounting points. A French cleat-style bracket helped ensure the boxes stayed level and easy to attach.
Final Result
The installed cornice boxes gave the room a more polished and intentional design. They concealed curtain hardware and elevated the overall look of each window.
John mentioned some initial hesitation about taking on the project, but the result exceeded his expectations. It’s a great example of how a relatively small upgrade can have a big visual payoff.
Want to See the Full Build?
Please support John by viewing all his plans here: https://www.johnbuildsit.com/plans.