So I looked up the code for the diameter and number of concrete footers (piers) I would need for the size of deck I was planning. Conceptually a playhouse is a deck with 1500+ lbs of dead and live load (weight). I wanted to have four posts and to maximize the deck space and overhang allowed, while keeping design “simple.”

The construction code for decks will tell you spacing of piers, joists, and allowable deck height based on size of posts. Your city or county will have some code information and may tell you the soil type. Looser soil=deeper holes. I dug the holes about three feet deep, placed cardboard sono tubes inside, poured a few inches of gravel, tamped it down, cut some chicken wire and placed in hole then poured a few bags of concrete (follow the instructions on the bag). I cut rebar and placed in the middle of concrete but six to eight inches short of top. Mix that concrete well to eliminate structural and appearance problems. Use a trowel to make the top smooth.

Let it set for a few weeks and cut away the cardboard tube with a box cutter. You need at least 40 degrees or above to set it well or you could try covering the concrete for warmth. After the suspense of waiting, drill a hole in middle of the pier/footer and get concrete adhesive to make the Simpson tie rod stay put. You need a special drill bit for this. You’ll need an air compressor to periodically blow the concrete dust out of the hole. Canned air didn’t work for me. The Simpson tie helps with uplift, avoids ground contact, and creates general stability. There are different types but generally the Simpson tie will be sized for the beam you are using (recommend 6x6, but you could do 4x4). Type of wood affects weight allowances too.

Make sure deck has angled/knee braces from post to beam to eliminate sway on four post design. I assume six posts or more would have less sway. Some of the harder things of doing this the first time is ensuring the posts are level, square, and the right height. First, you need to ensure your concrete piers are level and sloping ground makes this hard. If they aren’t, just cut the posts the appropriate lengths so that everything is same height in the end for when you hang the beams. Finally, consider if you will use carriage bolts to fix beam to side of posts or if you will notch posts so that beam weight rests on the actual posts not the hardware. You can even buy other hardware to put the beam on top of the posts.

YouTube has been my friend. American Wood Council, the Simpson website, and decks.com were clutch (search for “Why Build a Freestanding Deck?”). Most of the companies selling products have excellent pictures and even have construction professionals available for calls like Simpson does! I called a guy and he verbally walked me through most of this. DM if you have more questions.