Step 1. (Go to step 2 for new build.) With a pencil, draw out the dimensions of the inlay on your deck. Remove the deck boards by cutting along the lines with a circular saw set at 1.12 inches thick (*for 5/4 deck boards). Use a chisel and hammer to cut any deck board the circular saw will not reach (usually corners).
Step 2. Remove boards and expose the deck joists. Save these boards because you will reuse them in step 4.
Step 3. Screw 2×4 bracing to the existing joist the same width as the hole. The 2x4s should be 1.12 inches below the height of the joist.
Step 4. Cut the deck boards that you removed from step 2 to fit in between the joists. Screw the deck boards to the 2×4.
Step 5. Apply construction adhesive (such as PL Preimum) on the deck inlay, making sure that every piece has glue (especially the small pieces). Avoid glue from squeezing out buy keeping 2 inches away from outside edges and not over applying the glue.
Screw down deck inlay, making sure to screw down each element of the inlay. Pre-drilling your holes in the inlay is a must to avoid cracking the small parts that make up the inlay.