Water leaking through exterior floor and wall base
Well, as you can see, there is a reason for building the foundation up, or the whole slab up.  You can put some kind of water barrier to stop, what you are experiencing. You know that, sorry.  My thought of a solution would require you to cut a set of paralell slots, up against your house, close to the sill as you can.  You'll have to remove the siding, a couple pieces up, all the way around... anyway I would. Make the slot at least 6" wide. You will need a Tiling spade, it has a long handle, and a long narrow spade!  You are not in a frost area, water is your problem. I'd still make the hole 18" deep, and the top up 12". If you taper the space wide, from top to bottom,  that's even better!  This will be one pour.  on the back side (wall side) you will need a strong  waterproof membrane. Overlap and seal at the bottom of the pour, the same on the front of this "kick wall" but have it long enough to go back up under the siding from the in and out side. You may have to glue it on the top of the cill. A piece of copper flashing or allumium, coming down over the membrame, under the siding. I'd get 12" wide flashing, so a Z bend can go all the way over the cill. Do this but for your doorways, and you will no more seeps into your slab, metal frame house.  It is a fair amount of work, the head guys on your contractors crew, should be able to cut the deck.  Then the younger boys dig the footings, and the older guys measure the total width of the membrame. They need to put up a frame to pour into. Make sure the "boyz" taper the cill OUT from the house! It will require a few screw or fewer bolt holes in your deck. After the cill is dry, lap up the membrane, seal it on top, and add the Z flashing, put the siding back on.  It is not a terrible solution, but it will work! See what others say, not something we see here up NORTH! :)