Ours are vinyl-coated and we hand-mop them nightly, but with attention to using minimal water, cleaning up drips promptly, and not letting water run down between. Keep dampness away getting wet will ruin a tatami faster than anything. Store them either lying flat or standing neatly on a long edge, or they will warp. Our walls turned out not to meet at right angles so one end of the room was narrower than the other. The downsides are that it's a fairly hard surface (making learning ukemi more difficult) and it was a ton of work to build. Ki Society style picks up the feet a lot and is very bouncy tatami on a sprung floor like this suit it well. Over all that, a plywood floor then a protective tarp and a layer of tatami. Attached to the framework and resting on the tires, a lattice of 2x4's at about 14' intervals. My dojo constructed its new floor as follows:
