My 6x8 and 6x4 are both on my deck. An amazing amount of air draws up. Okay in the summer but i just laid 1.5 inch foam to try to combat the cold. All of my plants are in containers sitting on boot trays.so far so good.

That's a good idea. Is it soft foam like what you would use for a cushion? Or hard like the styrofoam used for wall insulation? Did you put anything under or over it besides the trays? Is this the first year with the Gh in this location?
Thanks!

My 8x12 Rion has been on a wood deck paved with 2x4s for about five years. I covered the decking with polypropylene boat carpet. Also ran the carpet up the inside of a 12x4 timber base. Secured it along the edges with pressure treated 1x2s. The carpet has held up well and I don't notice any cold air coming through it in winter. It's also permeable to water - water just runs through it and down through the cracks between the 2x4s. Here's a photo of it after a couple of years. It still looks like that after I shampoo it each June:

{{gwi:292645}}

My insulation is the wall stuff that already has plastic attached. I have hard rubber mats down the middle to distribute my psi a little. This is the 2nd winter for the 6x8. I put a gas heater in there to extend my season some. My fans run on power supplied by my solar panels.
The smaller one will only have kerosene lanterns to try to extend a few weeks beyond normal seasonal shut down. Then it is to be my storage area for pots etc.

Thanks guys. Good flooring options. Have either of you seen rotting around the Gh footprint either inside or out?

re rotting. None here. All the wood in and around the GH is high grade pressure treated yellow pine. I don't think it will ever rot. I've dug up scraps that I covered with dirt 30 years before, and they're like new. (I built this place 40 years ago, with a lot of pressure treated walls and decking, and buried a lot of scraps.) Around here, pressure treated that can see the sky will deteriorate over time. I think freeze-thaw loosens up the soft stuff between the rings and then rain washes it out, leaving only the rings. I had to replace most sky-facing decking and wall caps after about 25 years.

Same here. One on old pressure treat, one on new.