In moving our kitchen to another part of the house, I discovered (after removing the old floor cabinets) that the plumbing seems rather "unusual". The 3/4" lines comes out of the floor (slab) to go up to the old sink, but then cross over above the slab about a foot before then going down again under the slab to the washing machine about 12 feet away. Since that will now be a living room, I have to get these pipes below the slab. To do that I will have to remove concrete, then join the copper pipes together before replacing the concrete. That will put copper joints below the slab. I don't see any other way to do this, but I don't like having joints under the slab. Having not done this before, am I being too concerned about having these joints under the slab? My skills with soldering copper are pretty good.

"I discovered (after removing the old floor cabinets) that the plumbing seems rather "unusual". The 3/4" lines comes out of the floor (slab) to go up to the old sink, but then cross over above the slab about a foot before then going down again under the slab to the washing machine about 12 feet away."

I live in Florida where all our houses are on a slab. This is the way we pipe slab houses. Code does not allow us to bury solder joints under the slab so we jump up inside a wall and supply a fixtureand jump right back down again to the next fixture.

"That will put copper joints below the slab. I don't see any other way to do this, but I don't like having joints under the slab. Having not done this before, am I being too concerned about having these joints under the slab? My skills with soldering copper are pretty good."
I agree that solder joints under the slab not the best thing but sometimes you have no choice. I would leave the open hole alone for the first week or so to check for leaks and bury the copper under the cement pour covered by visqueen so it don't come in contact with the cement. Good luck, tom

For the reply. This was a kitchen "island" cabinet arrangement so these pipes are sitting out in the middle of the floor now, not in a wall.

". This was a kitchen "island" cabinet arrangement so these pipes are sitting out in the middle of the floor now, not in a wall."

But the tie-back was hidden as are all of ours. We pipe our sink islands so that the supplies are at the end of the run so there's no need for return lines. However you would still need to cap and bury the supplies after you removed the cabinet. Have a great holiday, Tom

I will follow your advice . Surely the joints will hold for something approaching forever if they are done right and I watch them for several days.

In all the years I've been plumbing I can only remember roughing in a town house with hard copper and joints under the slab once. The inspector made us pump it up to 225 PSI and hold it for 48 hours before he would sign off on it. Cheers, Tom