Making a room inside my garage

[rhinojm3]

I am going to enclose a corner inside my garage as a room , I plan on using 2 existing walls, and building
one solid wall (2x4 framed with sheetrock) , then the forth wall(2x4 with sheetrock) with a door.
I plan on anchoring the new walls to the concrete garage slab, however if I wash out the
garage on occasion this will get on the sheet rock at the floor level and eventually deteriorate .
What should I do at the bottom, should I build it up a few inches with maybe a cast lentil, or
what would be a good recommendation ?

 

[DIYRules]

If you are not soaking your garage or leaving standing water can you just tile the bottom of the new wall or use some waterproof paint on the garage floor and bottom of the new wall?

 

[rhinojm3]

Thanks!!
Not planning on standing water, just some off of car on a rainy day or if I lightly wash it off. Guess for the height of the tiles it could go up on cement board

 

[DIYRules]

OK then, good waterproof paint (the stuff used for basement floor or flat roofs) should do the job without the need for tiles.