Workshop floor suggestions?

[Benpointer]

Hi all,

 

We have a timber frame shed on our site approximately 9m x 4.5m, which I would plan to retain for a workshop.  The shed needs a bit of TCL.  It needs re-cladding and an new roof finish put on,  and ideal insulation adding within the walls when the cladding comes off (it's plastered inside and the plasterboard is mainly fine).

 

My main concern is the floor which appears to be crushed type 1, about 25-50mm ventilated gap, then 6x2s spanning across 2.4m or so from block walls, with a sleeper wall running down the spine of the building.  On top of the joists (which appear sound) is 18mm ply, nailed down.   In one are the wall plate has rotted our due to soil being piled up outside but we're hope the rest of the wall plate and the frame itself is ok. There are plenty of ventilation holes drilled in the walls below the floor.

 

I was planning to rip the floor out input in an isolated slab but... costs and the TPO are putting me off that idea.  

 

The issue is I have some heavy woodworking machines including a planer thicknesses that weights 220kg. 

 

Assuming the ply is sound will the floor be ok for a workshop or should I strengthen it?  Also any insulation option or should I just live with a cold floor?  (the ply is pasloded down so will be a right pita to lift).

 

Here are a couple of pics of the floor structure.

 

Thanks!