sod over crabgrass.
With his Ok I placed a roll of sod on my neighbor's heavily crabgrass infested lawn. I wanted to see if it would take without soil preparation. Similar to my test a few months ago in my irrigated back yard--which did OK, but weakened due to shade.
The sod laid on the crabgrass looked OK for a few days, but area was not irrigated, and it soon looked wilted. I watered a bit every day, but it soon looked rather brown. I took a photo after pulling the sod back to reveal the yellowed and flattened crabgrass underneath. Began on Aug 24, and it had been about 4 days, in the photograph.
Temps of about 90 predicted in next two days.