Winter ice IS a problem, but not as bad with insulation as it is with barrels - barrels need to be removed from the water. I just remove the poles and pull the pins that hold the sections together and then leave the sections in the pond. I tie them off to shore so they can't go over the dike if spring run-off is too great.
I built mine from scratch using treated 2x's and teflon coated screws. 3/4 decking wasn't much different in price so I opted for the thicker wood. One 4x8 section uses about 12 or 13 2"x4"x8' boards, 3-1/2" of insulation (pink or blue) board packed underneath and whatever method you prefer to connect or anchor. I used 5 2x6's and 5-1/2" insulation under the 8x8 section and 2x4's for the deck. Treated wood is awfully heavy. I framed it and laid out the deck in the shop then fastened only a few deck boards. Hauled it over to the pond and floated it and then screwed on the rest of the deck. You could build the whole thing on ice this winter and just wait for the thaw. Put in corner braces for extra strength.
Pat (Techno-Tractor Mom)
