I just had my shop site cleared and leveled. It is mostly volcanic tuff. I am leaning toward starting out with just that, an earthen floor, except for maybe one concrete bay for sliding under tractors and other vehicles. Eventually, I want wooden floors as a place to screw down forms for laminating wooden
greenhouse arches. The initial rectangle of the shop is planned to be 36'X72'. It
should be no problem with drainage, as this is at about the high point of my property and on a little ridge.
It poured rain the day after the work was done, doing to it what you might expect. Then we got a dry spell and I spent hours with my box scraper, polishing it. Then it rained some more and dried again. Once again I hit it with the box blade. With the rain that is going on right now, it is no longer turning to a wallow, but staying good and firm. I will repeat the process when it is dry again. Drying out doesn't take long with that porous tuff. I think I will like having that as a floor, once there is a roof and walls. It certainly is the flooring material I can afford.