[villagetinker]

Originally Posted by dewilson58

Very doable. Look at contractor websites.......Like Advance, or XCel Construction or PSL or T&D.........they give capabilities and show past projects.

I disagree you have to back up to a current bath, you just need access to the hot/cold water and drain. There is access locations other than under the slap or another bath. A lot of times you can access the water from the garage.

Obviously, always interview and get references.

Good Luck.

I agree with your comments, I was assuming that the 1/2 bath was on the opposite side of the house from the garage, and getting the water supplies would be problematic. I was coming from the layout of our house, where this would be difficult at best.
Upon additional reflection, if the OP is lucky, and the waste drain is on the same side of the house as the new 1/2 bath, then it might be possible to have the new toilet drain go through the slab and outside to the existing drain line, not sure about getting through the foundation. Also, if the other bathroom is on an adjacent wall then the water supplies and sink drain could be shared, JMHO.
I would get 3 estimates, with specific lists of what is to be done, and expected payment schedules, nothing up front. Construction must get ALL of the required permits.
Good luck.