I am adding on to an existing home. I will be contracting out most of the work but wanted to understand a few basics to assure the work is being done correctly. The addition will require butting a new slab to an existing slab. Part of the existing slab is in a kitchen area that has a bay window. I will be extending this room by about 15 feet. The existing flooring is tile and I will want the tile to continue onto the new slab. My goal is to minimize disruption of the existing dwelling while the work is being done. With that said. How will the concrete folks assure that the two slabs are flush (almost exactly) so the tile will be able to extend - and hopefully not be "crack prone".