We just had some additions made to the house and conditions made crawl spaces the way to go. One addition has a master bathroom in it. Both crawl spaces are basically dry; the plastic ground cover has condensation on the under side, as you'd expect. However, in the bathroom addition, where the sewer pipe goes through the foundation, the plumber left a hole about a foot deep and some water has collected. It's not sewer water. I think it is coming through the hole in the foundation. The sewer pipe is loose in the hole. Is it common practice not to seal around a pipe through the foundation like that? I could probably use hydraulic cement from the inside and fill in the hole. The pipe is at least four feet below grade outside, so doing it from inside would sure be easier. Anyone think of anything negative about filling in around the pipe?
The area around that or any pipe should be sealed. You don't want unwanted visitors coming in through the gap. I would use some sand mix concrete to seal it. The water may just be collecting in the the low spot from the condensation under the plastic but it could be ground water come in too.
It turns out that the sewer pipe is supposed to have room in case of settling, according to the local building code. I can plug the hole only with something pliable, like fiberglass insulation. At four feet underground on the outside, I don't guess I have to worry too much about critters getting in. I do wish I had paid more attention to the outside drainage before the backfill was put in. The contractor put in a perimeter drain which should carry away most of the water before it gets to this hole, but I could have packed above the hole with clay or something. I may really not have any problem as the water I found might have been there since the construction. I've drained it and will check it again every few days to see if more accumulates.
Check especially after a heavy rain. Unless your water table is real high, it shouldn't ordinarily be a problem. If it's not coming in the hole, then it could be a leak in the plumbing somewhere. Something as simple as a drain not sealed tight to the bottom of the tub.
I'm pretty sure it's ground water, and it could have been there for some time. It was a while after the construction was finished before I could get the gutters installed, and there was a down pipe dumping on the ground right above the sewer pipe. My walkout basement door is about 30 feet away and at least three feet below the point where the sewer pipe goes through the foundation. I don't have a wet basement, so I shouldn't have a water table problem at the level of the crawl space. I'm going to check the hole every few days for a while, and if no more water accumulates, I'll just stuff the hole with fiberglass insulation and fill the pit in the floor of the crawl space with gravel. Then I'll cover what they missed with 6 mil plastic and all should be well.
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