Am I asking for trouble if I sweat copper that will be under a slab? I have busted my floors up and I have to relocate some of the water lines to accommodate new design. The current pipes are over sixty years old and look pretty good. I think I once read that pipes under a slab have to be brazed. It looks like the original were sweat but I don't know how to tell.
we always had to silver solder any copper joints under a slab. i have repaired leaks under slabs with just regular solder tho. i really didnt have a choice. if you do id wrap some pipe insulation around the joints before covering them up.