Yurt Platform Plans
Here are three photos of us building the most recent 20' platform at our place. We followed the plans in the pdf at the bottom of this page. We used pressure treated because the mill couldn't get us any green hemlock, which I would have preferred. Notice no KD anywhere: it rots, even undercover. In the first picture, see how we laid beams on top of beams to get the correct angles traced out. No math involved. The second picture shows how one beam can be attached to another with long screws. Tie plates work too. Then we attached 2x6 tongue and groove directly to the beams without using any joists. Would not recommend. Run the joists over top the beams, every 16" or 24", cantilevering all around to go from an octagon shape to a circle. Toe-screw the joists down into the beams.
Here is a selection of platforms built by yurt owners. They all worked fine. You want to make sure to end up with a circle the same diameter as your yurt, plus or minus an inch is fine. For a deck and/or stairs, build them an inch or so separate, and one step (about 7") down. This will allow snow and water to shed off the yurt without getting in, and creates a slot for the outer wall fabric to go down and cinch up tight beneath the floor. At the very end are four sets of plans you can use. If you build a platform that you like and want to send us a picture of it, please do. Have fun!