The yurt platform has two major components in it - the floor itself and the bender board that wraps around the floor and provides an attachment point for the yurt frame and fabric. The exact diameter of the platform needs to be the size of the yurt before the bender board goes on. The bender board should be made from 3/8" plywood and stick up 6" past your finished floor height.
For example, a 30' yurt platform needs to be exactly 30' in diameter before the bender board is applied, a 27' yurt needs a platform exactly 27 feet in diameter, etc. The 6" of bender board will be visible from inside the yurt, so sand/stain/paint for visual appeal. The outside of the bender board needs to extend down to completely cover the deck framing and should be painted to withstand weather exposure. The exterior fabric wall of the yurt will extend down a few inches past the interior floor level, so make sure the bottom of the bender board is well protected from the elements it will see.
Here we present plans to build your own platform. Clicking will open the plans in a new tab as JPEG image. You can right click and "Save As" to send them to your computer's hard drive.