I noticed some water damage to the carpet and trim in the corner of a basement room that corresponds to the SE corner of the house and decided to investigate.
The house was built in '57. The foundation is essentially a simple rectangle built of cinder-blocks. The basement floor is poured concrete. The room was drywalled and the floor had trim all around so I didn't have a view of the cinder-blocks or the floor in the area of the water damage.
Pulling away the trim, I found the oddest thing: for about 5 feet along the south wall and 20 feet along the east wall, there is about a 1 inch gap between the floor and the cinder block. Also, it looks like when they poured the floor and smoothed it out they just kind of shoved the excess concrete over to edge of the floor and left it there to dry as a rough, uneven, unsightly, "lip" protruding up from the floor. This lip does not exist anywhere else in the basement, only where this gap exists. Everywhere else there is a nice smooth seam where the floor meets the cinder-block.
FURTHER, underneath the corner where the cinder-blocks intersect (and from whence the water damage seemed to be eminating) there is a cavity, probably about 6 inches deep. Shining a flashlight down the hole I could see a half inch or so of standing water. Poking around in the gap further away from the corner, I found that it was filled with pea gravel. I cannot tell how deep the fissure is or how it "bottoms out". All along the wall where this gap exists the dry wall was obviously water damaged and crumbling and needs to be replaced.
I cannot for the life of me figure out what the builders were thinking when they did this. Could there be a purpose for this gap? Drainage maybe? I'm trying to re-paint and re-carpet the room and would like to fix the water problem before I do so. It seems obvious to me that what is probably happening is that somehow water from the outside is getting in the gap and when the ground outside is very wet the cavity in the corner fills up and overflows onto the floor. One thought I had was to get some of that expanding spray foam stuff to spray in there to try and fill it up. But I worry that if this is some sort of drainage system, I might foul something up. Also, that probably wouldn't make a perfect seal everywhere and it might end up making it worse because then all I've done is make the reservoir smaller, thus causing it to overflow more often.
Anybody have any ideas?
Also, for what it's worth here are a few more clues:
1) I have big-time drainage problems in the back yard (to the east). It's probably been that way since the house was built. The problems generally don't tend to occur near the house but the soil does get very wet there too. I dug some post holes close to the house not long after some heavy rains and they kept filling up with water for a couple of days. 2) I said the foundation is a perfect rectangle. That is not completely true. On the east side there is a 2 ft section where the cinder blocks jut inward 6 inches or so into the basement. Interestingly, to the south of this point is where the gap and rough-edged floor begin. I can't tell what purpose this inward deviation might serve. There is nothing going into it (like a pipe or something) from the joists above. And I don't see any corresponding deviation or fixture on the outside of the house.
There's more but that's probably enough for now! Any help appreciated.
Thanks in advance,