Step 6: Lay out the platform
Because the decking came in 12' long boards, I made the treehouse 6' long. So you need to cut the decking in half, and lay it out. Leave a small gap between boards for drainage. Cut two of your 2×6 boards the same length as the decking, and the other four to the width of your decking less the thickness of two of the 2×6's (which will be more like 1 1/2" each).