We recently had 30" of water in a 1000 year flood. House is gutted so now's the time to fix a recurring problem I had. The previous owners made an add-on to the house where the concrete is only 2" above grade rather than the 6" for the rest of the house. Regular, heavy rain has slowly been rotting the lowest part of the wall. I can't prevent another 30", but is there something I can do to waterproof against the routine 3"? It's a straight 23' run with an outside corner and another 12' run. Both walls tie into the existing house and closed in a corner that was previously patio. I know the best solution would be to bring the slab up to the 6", but that is cost prohibitive at the moment.

Diagram of the slabenter image description here

  • Hello, welcome to Stack Exchange, and our thoughts are with Louisiana. A diagram and/or picture would help us understand your situation better. – Daniel Griscom Aug 24 '16 at 15:39
  • Thank you. I've added a rough sketchup diagram that I hope adds some insight. – kyle Aug 24 '16 at 16:51

If you can not work on the inside and raise it then work on the outside. What I would do is use a roll on sealant and add drainage along the exterior walls and draw it away. Consider getting about 10 ft away them use perforated pipes to leech the water lines into the ground and at its ending, possibly look into a 3 ft hole filled with rocks.

  • I had a backup plan that is exactly this: French drain along the wall and possibly a dry well. The problem with a dry well is our water table is pretty shallow. – kyle Aug 29 '16 at 13:12
  • You know the leech method is exactly why we use it due to the water table being as low as 30ft for wells. I am not sure what yours is at but 30ft for our area is extremely shallow. Its the same method used for septic tanks ( cesspools) We have about 100 ft of piping( 50 ft out then turns 50ft only 18 inches down. But mind you we are on acreage and so I do not know if you have the room to do such. – norcal johnny Aug 31 '16 at 4:09

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