My furnace sits in the middle of the house on the slab with a pit underneath about 12-14 inches deep. Moved in 2 years ago and had bad moisture problem. Took a while but found the problem to water in the pit. Noticed after sucking water out with shopvac that it was comming from the rear of the house where the patio is. Dug down 2 feet all around the patio and sloped it to a ditch at back.
Put a 3" perforated tile in and filled it in with stone. The problem still exists tho a lot less water gets in and it takes quite a bit of rain .
Now with a foot or so of snow melting and 2 days of rain there is much water in there.
It seems to be flowing in or around the duct/tile going form the pit to the patio door.
I'm wondering if the problem would be a crack in the foundation that is allowing the water to get in. Or would it be getting there without a crack.
Very frustrating 'cause I thought sure my trench and tile and the filling with gravel was the answer. Perhaps I should have dug deeper?