Is it safe to cut the post tension concrete slab foundation to fine sewer line for bathroom addition?
No, You must first locate the P.T cables, and because you said it is to find a sewer line im guessing this is slab-on-grade and not a deck. The only method for locating post tension cables on slab-on-grade is with Ground Penetrating Radar. If its on a deck you can use Ground Penetrating Radar or Xray. If you cut a P.T. cable you can weaken the structure and cause damage. P.T cables are known to shoot out of the side of a building when cut. And repairing the broken cable is extremely costly. You can learn a little more about GPR at www.subsurfacepros.
