Renovating lawn, killed off grass/weeds 3x, still green visible in lawn
I’m located in NW Iowa and first time renovating my lawn, leveling and planting with GCI tall turf type fescue. Two Saturdays ago I bought Roundup Weed and Grass killer you can buy at any box store. Double the dosage per instructions and the next day yard was killed. Two days later on Tuesday, noticed some green here and there which I knew could be normal, so the next day I used the same RoundUp and doubled the dosage again.
Days went by and noticed that the green was more visible throughout the yard. So three days ago on a Sunday I bought 41% Glyphosate weed and grass killer, followed the instructions, sprayed and as of today, there’s still green grass throughout my yard.
Do I just say f it and throw down screening top soil & grass seed over this weekend? Any help would be greatly appreciated