Last June, Chicago had continuous rains for 24 hours straight and my basement floor carpet got damp right in the center without any signs of water on any of the four walls. A few weeks later, we had little bit of rain and this happened again but not with the same intensity. I haven't ripped off the carpet yet (to figure out if there is a crack in the floor) but before I engage a contractor to replace the carpet with tiles or engineered hardwood, I wanted to know from you what is the best (least $) and worst (most $) I can expect after the carpet is ripped off.
My house is a 1955 single-storey (ranch) without a sump pump (never have needed it for the past 15 years), and my gutters are clean with the spouts extended atleast 2 feet away from the house. There is gradation all around the house but when the rains were there, we did have water stagnant in between our house and our neighbor's house (she extended her downspouts to the middle of both our houses, last spring, after a sewer backup in her basement).
Concrete is an extremely hygroscopic material. In other words, it soaks up water like a sponge! Water that sources at the foundation perimeter can easily be drawn direct to the middle of the floor without ever showing up along the walls.
It sound's like you are on the right track with a solution, however, I'm guessing that you and your neighbor have homes that are somewhat close together. That standing water will certainly find it's way to both your basements and a 2 foot extension isn't nearly enough. In the best case scenario, you want those spouts extended 4 to 6 feet away from the house and then be able to drain downhill after that.
If this is physically possible, you should consider adding a curtain drain between the houses and have both systems hook into that. Just be sure that curtain drain disperses the water downhill and away from both homes.
Get more tips here: