My home is weeks away from being completed. The flatwork was just poured yesterday so rough grading will take place this coming week. My builder is grading the entire front, sides, and 30 ft from the house in the back. I'm paying additional for them to grade an extra 100' in the back. The property is a mix of natural grass and weeds. My question is...is rough grading followed by 2" of topsoil enough to get a good lawn from Princess 77 Bermuda hydromulch? Can I get away with not killing the existing weeds and just grading? Should I roll the lawn before topsoil, after? Total lawn area will be about 34,000 sq ft.

bump....do I need to kill the existing grass and weeds first? It's a lot to do.

All of the sod prep I've ever done and seen recommended involves killing the existing turf. Roundup followed by heat and then raking is usually sufficient.