How to Case a Window with DIY Wood Trim
Learn how to case an existing window using 1/2" plywood and 1x4 MDF boards. This simple DIY window casing adds a clean, finished look without replacing the window.
Servings: 1 Window
Cost: $300
Equipment
- Table Saw
- Miter saw or suitable saw for straight cuts
- Finish Nailer
- Brad Nailer
- Tape Measure
- Sandpaper or sanding block
- Painting supplies
Ingredients
- 1/2" PureBond plywood amount depends on window dimensions
- 1x4 MDF boards amount depends on window dimensions
- 2" finish nails
- 1 1/4" brad nails
- Wood glue
- Wood filler
- Paint
Instructions
- Measure and cut the plywood. Measure the depth of the window opening and rip 1/2" plywood to fit. Measure each window individually.
- Install the top plywood piece. Cut the plywood to fit across the top of the opening. Position the front edge flush with the drywall and secure it with 2" nails.
- Install the side plywood pieces. Measure and cut both sides to fit between the top piece and window sill. Secure them with 2" nails.
- Cut the MDF side trim. Measure from the top of the window opening to the sill. Cut two 1x4 MDF boards to fit.
- Attach the side trim. Apply wood glue to the plywood edges. Position the MDF boards, leaving a small plywood reveal along the inside, and nail them in place.
- Install the top MDF trim. Measure the full width across the installed side trim. Cut the top MDF board to fit flush with both outside edges. Attach using wood glue and 1 1/4" brad nails.
- Fill and paint. Fill the nail holes with wood filler. Let dry, sand smooth, and paint the finished casing.
Notes
- Times are estimates for one window, assuming the existing sill stays in place. Actual drying time depends on the products used, and additional coats may take longer.
- Estimated Cost: Varies by window size and materials. The original project cost under $300 to case multiple windows throughout the house, using prices at the time.
- Measure every window separately. Openings may vary even within the same room.
- Use the smoothest plywood edge toward the front for a cleaner finish.
- Keep the plywood flush with the front edge of the window opening.
- Leave a small, consistent plywood reveal inside the MDF trim.
- Check that the existing window frame and sill allow room for the casing without interfering with window operation.
- Confirm suitable nailing locations and avoid concealed wiring, plumbing, or window components. The original tutorial does not specify the framing or nailer settings.
- Allow wood filler and paint to dry according to their product instructions.