Both aart and I are from the mitten. 
I got the heavy duty tarps that were 8x10, because that size made the most efficient cover for my run. One spot got a wear/rub not quite through from a metal roofing corner, but that was it.
I used zip ties to tie the tarps down, and that worked really well too. Another nice thing: Black side up in the cold months for absorbing the sun's heat, and silver side up in the hot months to help reflect it.

I got the heavy duty tarps that were 8x10, because that size made the most efficient cover for my run. One spot got a wear/rub not quite through from a metal roofing corner, but that was it.
I used zip ties to tie the tarps down, and that worked really well too. Another nice thing: Black side up in the cold months for absorbing the sun's heat, and silver side up in the hot months to help reflect it.
If you want some grass gone, and I mean, GONE, roots and all, chickens are the least labor intensive way I can think of to get it done. Because they do all the labor! 