I use foam insulation boards around the bottom edge of the patio hoop to keep the chill out. One board cut into three pieces lengthwise is about all I need. I bet that would work as the floor of your gh. One sheet was a little over $9. at HD. I store it and use it over and over. I have a two half sheets that I use on the north side of the hoop where the wind comes whipping across our hill. Not the prettiest gh, but it gets the job done.
