Waterproof flooring for a shed?

Just had a new shed built to replace the decades-old one that had taken a big branch to the roof a couple years back. It's all done and ready to go, but as I look at it I'm wondering if I should put down something to waterproof the OSB floor and generally make it easier to keep tidy before I start moving stuff - including a lawn tractor - in and making a mess. My first instinct is epoxy floor paint, but I'm also starting from zero knowledge here, so I'm looking for suggestions or thoughts about 1) whether it's even necessary, and 2) if so, what to use.

I'm getting ready to build a lean-to add on to my garage.  I have chosen to go with 6" PT deck boards and build it like a deck, then lay some vapor barrier (maybe some leftover tyvek) and 1/4" OSB on top.  That way the structure is all PT and the bottom of the OSB will have a tough time absorbing moisture from the dirt.  For the top I'm just using some junk leftover exterior latex.  I don't expect it to last.

If you haven't already bought it, you could buy some of the good expensive water resistant OSB like Advantech.  It's rated for something like 100 days of water exposure.  I used it in my house and it's not cheap, but it's impressive stuff.

The glue they use for it is basically gorrila glue, so any of the exposed wood can absorb water, but it can't penetrate into the wood.

If the OSB is already down...

I would glue down Armstrong vct tile.

Only about $1 per square foot.  Tough as nails.  They use it in car showrooms.  I've had it as the floor of my enclosed race trailer for 20 years.  tough!    Super easy for a novice to install.

Define waterproof.  Won't buckle when wet or does it have to be a water tight swimming pool?

 Trex like material?  Rubber bladder?

I'll try to address all the points that have been raised. I don't need to hold water, just prevent it from causing damage. The shed is well-sealed, and I don't anticipate large amounts of water being brought in - just things like wet wheels on the tractor or a tarp with water on the surface. The shed was built similarly to what Curtis described, with a moisture barrier over pressure treated lumber, then the OSB on top. The OSB is Huber Blue Plus. I like the idea of the VCT tile - that might be the leading candidate at this point.

That Huber is very much like the AdvanTech I mentioned.  It will do well.

A good floor paint will probably keep it looking nice, but I wouldn't worry about water too much.

I've bought 8x12 sheets of linoleum for real cheap at menards, I imagine the others have the same. You could roll it out and tack it down with some roofing nails or something. 

I just assumed OSB would make a terrible choice for flooring because of swelling and delamination, but I guess my experience with OSB isn't current.  This site even discusses using OSB as finish flooring: https://www.silvaris.com/using-osb-as-your-primary-floor/

In reply to 1988RedT2 :

I only learned about the new stuff about a year ago.  I had to re-do the subfloor in my house but I knew it had to live outside while I slowly did the project.  Someone turned me on to the Advantech stuff.  The OSB I got is guaranteed for a year of weather exposure, so if you were framing a house and had to pause for zoning, inspection, or finances, it could sit exposed without a roof for a year.  It's a "no-sanding" guarantee, so even after a year you won't even have to sand it.  They guy that sold it to me said that if it rains on your exposed subfloor, you just sweep off the puddles and keep doing your thing.

The loft I rented in L.A. had OSB in the kitchen for flooring.

In reply to Curtis73 (Forum Supporter) :

I left a cut off piece of advantech out behind the garage for about a year, totally for science and not because I'm lazy, and besides being discolored it seemed pretty well unscathed. I've always used it for subflooring under bathrooms in case of a water leak that doesn't get discovered for a while.

In reply to gearheadmb :

I partly went with Advantech because the part of the floor I was replacing was above a dirt crawl space.  I have a good vapor barrier on the dirt, and the crawl space shares air with a dehumidified basement, but I splurged.  I was also putting down a pretty exotic custom figured Maple hardwood, so doing 6 sheets of the good stuff didn't seem like overkill... much.