Bricks, Masonry, Asphalt and Concrete - Patio wall on concrete slab

My patio in the back has been truned into a family room by the previous owner. The 3 walls are basically drywall inside and plywood panels from the outside. The base are 2 X 4 wood boards sitting on the concrete slab.

Much of the base boards have rotted away. I believe they built this around late 80's. I have recently replaced large section of them with 2 X 4's. I primed and repainted them. I caulked the area between the wood boards and the concrete slab.

But, I sure hope there is a better method to prevent future water damage.

So, what would you do when wood boards simply sitting on a concrete slab?

Thanks
fh

Keep the water away from the outside of the wall. The 2x4s sitting on the concrete should have been pressure treated. The plywood on the exterior should have a water replellant treatment (wood stain). Pressure treated doesn't last forever, but it is the best you can do for a wood wall.

Dick