Things You'll Need
Instructions
Take measurements and then plan your work. The best play sets have multiple levels, built much like inter-joined tables of differing heights with accessories that bring the set together. Visit a local park or playground that has a wooden play set to get ideas. Use the ideas that work; ditch the ones that don't. Observe how kids play, which features they use and which they ignore. Plan your new wooden playground based on your research.
Build the platforms. Platforms are like tables and are the base of your play set. All of the accessories to be added are ways onto, off of or between these platforms. Once you have decided (from your plan) the number of platforms you need and the situation of those platforms, dig post holes (typically 18 inches deep and 4 to 6 inches wider than the diameter of your posts). Use a digging bar to break up the earth and a shovel to remove it. Set the posts either in concrete or on concrete if you use anchors to attach the posts. Use a level to set posts to true vertical. After the posts are set, use either 2-inch-by-6-inch or 2-inch-by-8-inch joists (set 16 or 24 inches apart) and decking (3/4-inch plywood or 2-inch-by-6-inch or 2-inch-by-8-inch) boards set side by side perpendicular to the joists and screwed down to the joists (with a 1-pencil width gap) to set your platforms.
Add accessories, with the fun stuff first. At this point, you have what amounts to different sized tables but none of the fun that makes it a play set. Accessories for play sets are limitless. Forts, slides, poles, bridges (both rope and rope/wood bridges), see-saws, swings, stairs, ladders crawl tubes and ships' steering wheels are common accessories to the sorts of playgrounds kids love. Use your imagination and let it run wild. Pretend you are a kid again, and you will be hard pressed to go wrong.
Make it safe. Now you have platforms and slides, and ladders and every kind of fun and imagination-inspiring accessory a kid could possibly want, but the play set is not yet safe. Add railings where necessary. Asphalt shingles work as excellent foot pads to limit slipping that sometimes happens if wood gets wet. Keep in mind that if a kid can climb it, the kid will climb it, and if the kid can get hurt, he will get hurt.
When you think you have made it safe, invite your kids to play on the new playground and stay to supervise. Search for all of the things you never thought of making safer while watching your kids play. If you have to say, "Be careful," there is likely something that you can do to make the system safer.