Basic Plans to Build a Patio Deck

Groundwork

• Lay out your post positions. The corner posts should be laid out in a square or a rectangle and should be sized as some multiple of eight such as an eight-by-eight or eight-by-16. Check the corners for square by measuring diagonally from corner to corner. Both measurements should be the same. Dig post holes on each corner and every 4 feet in between each corner post, about 2 feet deep. Stand the 4x4 posts up in the holes and pack dry concrete pre-mix around the posts. Plumb the posts with a level and make sure they are all perfectly in line. Water the concrete and allow it to set overnight.

Joists

• Determine what height you want the finished deck surface to be. Subtract the thickness of the decking and mark a corner post. Lay a scrap of 2x6 or 2x8 treated floor joist material against the post under the mark and mark the bottom of the scrap. This marks out a notch that must be removed from the post. The bottom of the notch actually bears the weight of the floor joist and therefore the deck and its load. Level off of this notch with a water level, laser level or bubble level and notch all the posts to receive a joist. Cut joists where the joints will fall out on a post. This way the notch will support the joint and prevent it from sagging. Hang the joists into the notches and screw or lag bolt them into place. Cut off all posts at the same height, leaving enough height to support a handrail if desired.

Deck

• Lay the decking onto the joist frame starting at one edge. Place all butt joints over a joist if the deck is wider than your material is long. Measure off one edge on both sides so the decking stays straight overall, otherwise a few crooked boards can throw your nice deck out of whack. Screw the decking down with treated, exterior/decking screws. Be sure to slightly countersink the heads to prevent injury, and whittle or sand any splinters away that the screwing process raises.
  The optional, but recommended, handrail can be made with decking boards screwed to the tops of the support posts. A board outside, over the top and inside at the top will provide a beefy and strong handrail. Another rail or two set lower will help protect pets and children as well.