[Ford Prefect]

When I resodded my yard I did take out the old sod. That's a waste of good potenial fertilizer once it breaks down. I had a guy come in and spray round up on the old lawn, then waited for it to die. Once it was dead, I put in the new top soil over the dead grass and laid the new sod. Not only does the old gtrass enrich the soil, doing it this way saves labour and money.

FWIW, I now have the best grass in the neighbourhood. Just don't skimp on the top soil. All of the worst lawns are the ones that people cut corners on and didn't put on enough top soil.