Hi All- I’m weatherizing an exterior building for a wood shop and wonder if someone with more experience than me would troubleshoot  this floor assembly? Thanks!

Insulated  woodshop floor design 16×20 wood structure

Existing flooring is random width, square decking approximately 1×6 (actual thickness is ⅞”) with gaps. The floor frame is 2×8 southern yellow pine joists at 16”0/C with spans 7ft 2 in. across 6×6 SYP  continuous beams that run under eave walls and down the center. The continuous beams are  supported by 8” sonotube footings. The beam that runs down the center of the floor has three 8” sonotube supports, at the ends and the center. The outer beams  each rest on  four 8” sonotubes spaced at approximately 6ft o/c. The existing floor with these relatively short spans  feels quite solid.

I want to insulate the floor and have an inexpensive, continuous floor that I can use casters on.

I plan to first lay down a layer of expanded steel lathe as a rodent barrier (it’s  cheaper than hardware cloth). 

The next layer would be 2” of Owens Corning Foamular XPS 150 or 250,  taped at the seams so it doesn’t leak air. 

The flooring layer will  be ¾” t&g Advantech. 
Maybe it would make more sense to do a layer of poly between the foam and the Advantech?

My questions are these:

• Will the Advantech floating on the foam without sleepers work? 

• Will it be spongy or noisey?

• If I don’t plan to use any machine heavier than 500 lbs, will the Foamular 150, at 15psi, work, or should I upgrade the foam to 25psi (foamular 250)?

• I’m thinking of first screwing down the existing floorboards so they’re very well fastened to the joists, then screwing the Advantech through the foam and lathe and into the floorboards.

• The Advantech is tongue and groove on its long edges but not the ends. Should I router the ends and use some kind of spline to ensure the floor plane doesn’t wiggle where the ends meet? Or just screw the end pieces at closer intervals on both sides and make sure the planes match?

• I plan to fasten  the Advantech with 4” deck screws: what should the fastening schedule be?