Experts and BHG readers answer.
Rocky sloped front Yard no top soil do I need to dig up and re-seed
You'll have the best results if you work to improve what you've got, rather than digging it all up and starting over. And just as a side note, seeded lawns do better in the long run than sodded ones. It sounds like your thin, patchy lawn is suffering from a lack of quality soil and the nutrients it would offer, in addition to drought stress. Spreading a thin layer of compost over the entire surface would do more good than topsoil, because the compost would hopefully contain partially decayed plant matter that will improve the soil's tilth and aid in the beneficial soil bacteria that will help your turf thrive. If possible, add a layer of compost (up to 1 inch thick) annually. You can also reseed the thin or bare spots, but you'll have to water regularly for several weeks while it's coming up and periodically through the hot summer months to keep it alive.