I have a drainage issue with my townhouse and I am in a dire need of a solution. There is an area in between my home and the next home that is pretty flat, about 30 feet long and 11 feet wide in between the houses. During the rains, most of the water pools next to my wall, so there is a slight slope towards my house. I attached pictures of the area from multiple angles.
The house does not have a basement and is slab-on-grade. The wall in question is the wall of the garage, and I can see efflorescence on the cinder block next to the wall on the inside. Somebody suggested a french drain dug 12 inches wide and 12 inches deep and only 12 inches from the foundation of the home, which would also be re-graded towards the french drain.
My concern is that 12 inches is too close from the house and that there is not enough slope in the area (which is pretty flat) to drain it to daylight. Do you think it is too close? What would the minimum slope be over 30 feet of french drain to make it work?
Any suggestions or alternative solutions will be greatly appreciated.