Cracked basement floor?
Question:Just curious to the reason why my basement floor has cracked over where the sewer line runs across the bottom of the basement floor..it has a crack running all the way across the basement..in one area its got a good bit of gap in the crack..Thanks
Answers:
It's a stress crack. I suspect the installation of the sewer pipe was not at a sufficient depth, which creates a "less than normal floor depth of 4-6", or the material under the pipe (gravel or stone) was not compacted properly. If the crack is less than 1/8 inch (or a quarter couldn't slip into it), I wouldn't let it concern me. If it allows water to seep upward, I'd bring in a good concrete man and repair it. I hope this helps.
Rick M.
the reason that the crack runs across the lines is that it is the weakest point in the foundation, as the cement is not solid. This is normal for basements and you shouldn't worry about it unless it starts to fissure, or one side of the crack begins to rise or fall, but that is fairly uncommon.
I would be a little curious as to why the sewer line runs across under the floor! If the house is 50+ yrs old, and in a major city, then that would be normal. Those houses have a soil trap. Most houses you will find have the line go into the floor at or neer the wall where it exits the foundation. If your concerned, then have a plumber run a scope or camera down the main line. You can see if there is a break in the line that way. Get some good hydraulic cement patch or caulk in the crack. If one side of the floor seems to shift or rise, then get a professional to check it out.
The floor is probably cracking because the trench that was dug for the sewer pipe (before the slab was poured) was not properly compacted and settling has occured.
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