When you want new lawn you can top-dress your lawn and overseed or you can spend a bit more money and install new sod. But there is a third option, if you can get by the nasty initial look.
Hydroseeding is super quick and you should have a new lawn in 10-14 days depending on weather and site conditions.
The spray includes: seed and wood fibres with fertilizer and glue. It looks a bit freaky but it's more effective than simple overseeding and much faster than new sod.
I admit I wasn't sold the first few times I saw hydroseeding done on large sites but it works. Last year we did a large boulevard section and the lawn turned out great.
So, remember, there is a third option when you want a new lawn. Consider hydroseeding.
Vas Sladek, B.Sc., CLHT