Underslab Plumbing

After being held up for weeks I finally have pipes installed!  The main 4 inch pipe sweeps nicely under the foundation.  This pipe is bedded in sand so that rocks won’t poke thru.  There is also a vertical pipe that rises to grade for servicing the pipe (cleanout).

Once under the slab the pipe rolls up to a very funky PVC tee which has an extra 2 inch port on one side.  The bottom of this fitting connects to the septic system.  The main 3 inch port (would be the tee port if this were a standard tee) connects to the toilet.  The other 2 inch side port connects to the shower drain.  The shower drain has a trap installed under the slab.

The top port is bushed down to 3 inches and runs over to the wall.  The kitchen sink, vanity, and washer drains will go here.  The stack vent will also connect to this pipe.


You notice that the top pipe is very close to the top of the slab.  In fact near the wall its only 1 inch below the surface.  The radius of the elbow is going to make it tough to install the sill boards for the wall.  Why on earth did the plumber do it this way?

He wanted to reduce the pipe size to 3 inches at the cleanout and run 3 inch lines in the slab.  This would have lowered all the pipes by about 4-5 inches and put them just below the level of the concrete.  The plumbing inspector is a ball buster and *might* have given him a hard time about that setup.  Not wanting to cut the job apart, he did it the way he thought the inspector wanted to see it and not the best way for this job.  The stupidity in this state is amazing!



Tomorrow the plumbing inspector will sign off in the afternoon.  I will finish up the slab work and get the building inspector to approve the slab and hopefully next weekend the slab can be poured.

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