As I mentioned in my previous post, it is time for some wood-work. But first...
... a barrier against those pesky wood-eating insects. I used 10" wide aluminum flashing. Since aluminum is quickly corroded by chemicals found in both cement and pressure treated wood, I protected it by sandwiching between layers of tar paper. Both tar paper and aluminum are soft enough to be easily punched by placing the sandwich over one of the J-bolts with a 5/8 socket over it. A sharp rap with a hammer and, voila!, a hole. I learned this trick (and many others) from Chuck Henson. Chuck, you live on in my life.
The joists were laid out and end-nailed through the band board. Then, using lumber not fit for joists, I cut and nailed blocks to run down the center line to prevent rolling. One of the joists is doubled all the way across. This is to provide a full nailing surface for the end of the decking. I really hate trying to nail two butting pieces of sheathing or decking to a single 2X edge so I almost always double my joists, studs, or rafters where butting will occur. I also doubled other joists from the wall to the center beam under the area where the battery will be situated.
Before the decking was nailed down, I placed some polyethylene sheeting in the ground below the floor to keep moisture from rising to the wood. The ground was sloped from all walls and corners to the center of the back wall where there is a pile of rock and rubble covering a single un-mortared joint at footer level. Condensate will collect on the plastic sheet and run down to this drain slot and outside near the low point of the elevation.

I used Advantech decking because it has a tongue and groove milled into the long edges. This makes a nice sturdy joint without the need for additional blocking between the joists. HOWEVER, the manufacturer in all its wisdom decided to keep the overall 4X8 format of plywood and other sheet products. This sounds great until you realize that the tongue is milled from part of the 4' dimension. So, you loose 1/2" inch of coverage for every sheet you put down. In this tiny structure, that amounted to only 1 1/2". In my shop, however, this added up to 4" over the 32' length. I had to nail down a strip of 1X to make up for the loss in that case.
With the decking nailed down, I ran to town for a load of 2X4 and OSB. Time for some walls. I like building walls on the floor. This makes
everything easier. But, the price is that you eventually have to get the wall vertical. Blocks were nailed to the band board to prevent the wall from sliding off the floor while it was being raised. I used a crowbar and blocks to get it high enough to get the farm jack under it. The jack was able to lift it another 3 1/2 feet. From there I used lengths of 2X4 to form legs to hold the wall in place while another set of legs was positioned. I would lift the wall until the legs swung perpendicular to the floor then rest it. Another set of legs would then be nailed for the next lift. In this way, the wall was "walked" up until I was able to make the last push in one go. The tire is there to keep me from being completely flattened should something go wrong.
One wall up, three to go.