How to build a large outdoor bench with 2x4s and 2x6s with X back. Easy DIY tutorial from ANA-WHITE.com
7 - 2x4 @ 8 feet long
2 - 2x6 @ 12 feet long
2 - 2x2 @ 8 feet long
2 - 2x4 @ 43-1/2" (back legs)
2 - 2x4 @ 57-3/8" (back horizontal boards)
2 - 2x4 @ 61-3/8" (seat framing front and back)
2 - 2x4 @ 23-1/2" (seat framing ends)
2 - 2x4 @ 20-1/2" (seat framing under supports)
2 - 2x4 @ 23-1/2" (front legs)
4 - 2x6 @ 64-3/8" (seat slats)
2 - 2x4 26" (arms)
2 - 2x2 @ 16" (decorative back vertical pieces)
3 - 2x2 @ 22-5/8" - both ends cut at 45 degrees, ends are parallel, long point to long point measurement (long X pieces)
6 - 2x2 @ 11-3/8" - one end cut at 45 degrees, longest point measurement (short X pieces)
Please read through the entire plan and all comments before beginning this project. It is also advisable to review the Getting Started Section. Take all necessary precautions to build safely and smartly. Work on a clean level surface, free of imperfections or debris. Always use straight boards. Check for square after each step. Always predrill holes before attaching with screws. Use glue with finish nails for a stronger hold. Wipe excess glue off bare wood for stained projects, as dried glue will not take stain. Be safe, have fun, and ask for help if you need it. Good luck!
Build the back with 1-1/2" pocket holes and 2-1/2" pocket hole screws. If you prefer you can also add the decorative pieces now (may be easier to work on a bench top instead of at the back of the bench later on).
Build the seat framing either with pocket holes or 2-1/2" self tapping exterior screws.
Attach seat framing to back with 2-1/2" exterior screws.
Attach front legs to front of seat framing with 2-1/2" screws.
Add the arms. I used 2-1/2" screws from top and back to attach.
First, add the 2x2s that are 16" long, centering so there is 18-1/8" spaces between the 2x2s and 2x4 back legs.
Then cut out all the pieces for the Xs on the back and fit in the openings. Once they are all fit, mark the pocket holes that need to be drilled on the back side and also the joint (What I do is put an A and A on the two pieces at the joint, then a B and B on the next two pieces at next joint and so on). The reason for this is you want to avoid a situation where your pocket holes are on the front of the bench.
On the 45 degree sides, you can drill a pocket hole, there won't be much material removed, but it will work just fine. Trust me on this one.
Then attach with 2-1/2" pocket hole screws and glue from back side.
It is always recommended to apply a test coat on a hidden area or scrap piece to ensure color evenness and adhesion. Use primer or wood conditioner as needed.