I'm not from NE Ohio, so I can't tell you what grass to grow, but it's late in the year to establish a lawn, so unless you have a very mild autumn, you'll likely have a lot of patches come spring. You may consider doing this in the early spring or maybe even put down sod.

I would skip the fine fescue as it's made to go under trees.

I have experience with tall fescue and it likes to be slightly buried, so I tend to put it down first and then lightly cover with compost.

Also, keep in mind that rye germinates fast and KGB germinates slowly, so what may happen is the rye will do OK, but KGB won't.

Before nuking your yard, I would have done a soil test to find out why the TF didn't work. You may have been able to salvage it with some core aeration and fertilizer. TF is more drought tolerant than rye and KGB.

Thanks for the response, to clarify, the TF worked just fine, it's just not ideal for a yard with pets and kids because it's not soft. The KBG/Rye blend in the front yard (full sun) is doing just fine.

The big question is whether I should add compost or topsoil. That's a lot of work spreading that I would rather skip...

I trust more a mix of three types....kentucky blue, perennial ryegrass and fescue....each giving its best in different weather conditions of northern zones.
Aside from that though, your decision to over seed at this time might prove to be a bad one.
People often make the mistake of looking out the window at the weather for a particular day and make decisions that cost money based on that.

If only grass grew in air....we could have a fine lawn anytime during the summer.
But, unfortunately, it needs warm soil---not warm air, to grow and time is running out on suggesting the soil temperature is anywhere near the temperature that would welcome grass seed to germinate. Plus, the time that it would need to harden off before a winter freeze kills the new sprouts.
From your measurements I get you needing about ten and a half cubic yards to put down 1/2" of soil over the 7000 sq. ft.
Whether its topsoil or compost is a matter of choice...compost, I would imagine would be very costly for that amount.

I would suggest you put off this job until the spring due to the weather not being conducive to decent seed germination.

I think you ran out of time. Spraying the RoundUp was your final mistake of the season.

Given what you're saying, I would find a bag of 100% Kentucky bluegrass. Call around to hardware and feed stores until you find one. I would absolutely stay away from any mix of rye and KBG for the reason listed by kidhorn. Rye comes up in a week and looks like everything is hunky dory...so you back off on the watering right before the KBG was going to sprout. You end up with nothing but rye. If you really want rye, then put the KBG seed down first and in 2 weeks, put the rye down. That won't hurt a thing. Walking on seed that has not germinated is no problem.

If you don't use compost, then don't use topsoil. Topsoil is a mistake 99% of the time. Compost is more of a user's choice. If you want to spend that money, go for it. You would get a much MUCH better bang for the buck by using alfalfa pellets (rabbit chow) instead. App rate is 10-20 pounds per 1,000 square feet for the first app. Stick with 20 pounds per for subsequent apps. I would use that and forget about starter fert. If you go ahead and seed now, roll the seed down to ensure it is in contact with the soil. Then do the 3x per day watering to sprout the seed...for the next month with KBG. You don't need all the KBG to sprout, because it will spread to fill in the next few years. But the more you get to sprout now the faster it will fill in next season.

Thanks for the input guys. What I've read says OK to plant KBG/RYE in 60+ AIR temperatures, which we will have for the next month based on averages. Regardless, I'm going to do it now, so I appreciate the input.

Thanks for the input guys. What I've read says OK to plant KBG/RYE in 60+ AIR temperatures, which we will have for the next month based on averages. Regardless, I'm going to do it now, so I appreciate the input.