I would skip the tilling part of your plan. Not only will you have settling problems for years to come, you will disturb tons of seeds and roots that will make your life miserable.

What are you planning on growing in place of the Zoysia is probably one of the most important questions. Where do you live (city/state)?

If you have a local store near you go and get ALL the empty cardboard boxed. You can sheet mulch your property and get excellent results. This method when bringing in topsoil, but brings up other questions? Why are you bringing in topsoil? Do you have severe leveling issues, Do you have drainage problems?

The most simple way to replace a lawn is to kill it (like you are doing). Water it for a week, then spray it again. From there you are free to sod or seed. Doing this in the proper time frame for your area makes a big difference. Cool season lawns need to have had this process started 2 weeks ago, warm season lawn, 2 months ago. Strarting at the wrong time leads to competition for weeds.

I'm going to be using tall fescue. I live in Maryland and whoever decided zoysia, which is green four months of the year, was a good idea was out of their mind. The top soil is just something to put the new seed in. I can't tell you if the current soil has issues, buy my experience with this yard has been that adding a layer of good quality soil on top pays. It's fairly level but will likely make a few improvements. I understand the argument for not tilling, but have trouble imagining how to get the new seed in the ground without causing the same issue, particularly since almost all viable weed seeds would be in the top few millimeters of the current soil. The tilling is solely to 1) get rid of as much zoysia rhizomes as possible, assuming some escape Monsanto's wrath, and 2) so I can blend the new top soil a bit and not create issues for the new grasses roots being able to break through.

I did get a late start and wished I had begun spraying the zoysia a week or two ago, since I know multiple applications will be needed, but MD extension says seed planting is still okay in October and I've had good results from October in the past.

The last bit to be killed was spayed on Saturday and fertilized it today to hopefully spur some growth. By labor day I should see results from the first application and be ready for a second. At that time, I'll probably dethatch to expose any remaining green and spray it again. For the first two applications I'll use the Round Up Super Concentrate (purple cap) since it doesn't contain Diquat, like Round Up Concentrate Plus (red cap) Diquat could kill the leaves faster than the roots, which is an issue when killing zoysia. I'll do a third application around the 15th with RU Concentrate Plus. I figure by Sept. 24th I'll be able to start removing the zoysia and hope to get the seed started the same weekend. If life gets in the way, then hopefully by Oct. 8th/9th.

Check out UltraKill at Lowe's, it's significantly less expensive than RoundUp, same AI.

I think rototilling is a bad idea for many reasons. In your case I believe it will convert a few hundred long rhizomes into tens of thousands of shorter rhizomes as the blades yank them apart and shred them.

Is the current level of your soil at or below the level of any concrete around the yard? Or does it crown up higher than the hardscape? I see a lot more situations where the people need to be hauling yards and yards (and yards) of topsoil away following decades of annual topdressing. If adding dirt to your grass improved it, then you have other issues. My concern with adding soil is that it will change the drainage flow. At worst you will create a 2-inch high barrier around your house (a moat) and that will back up into your basement. Water should drain away from all the buildings and flow out to a street or other drain/ditch. If you have that now with no low spots, then I would leave the level alone.

If a landscaper were doing this, he/she would kill the grass first and likely scrape it all off with a tractor and a boxblade. With no obstacles and if you are already close to having the right amount of soil, an experienced driver can dress 5 acres in a morning. When you're paying by the hour for equipment like that, you want it to be efficient.

The tractor and box blade is not something you rent and learn to do on the job. You might be able to kill it all and shred the dead grass with a power rake set to just barely scrape the soil. That will leave you with a lot of chaff to rake or blow off. Then you could seed.

There are no leveling issues other than a minor dip or mound here or there. The lawn is much lower than the house and the entrance walk slopes away from either. I can easily add a couple inches of soil without causing any issues.

1) If I avoid tilling, what would be the best way to remove the dead grass? Would I just mow it as close as possible, maybe then take a string trimmer to it thereafter to get it down even closer?

- This stuff is super thick to the point I plan to rake it really hard this weekend to make sure the Round Up can even reach the hidden parts.

2) After that's done, would I just throw the new soil on top leaving the current soil as undisturbed as possible?

- My thought was that new layers of soil should always be somewhat blended so you don't create issues for water draining and root penetration, but if you think that's not so much a concern in this situation as leaving it undisturbed for other reasons, then I'm open to not doing so.

3) Does anyone have concerns about using a newspaper or cardboard layer between the old soil and the new?

Thanks again for everyone's help.

Use a dethatcher/power rake to tear out the dead grass.

Good to know you don't have drainage issues or potential issues.

1. Power rake (rented) will chew up the zoysia and any stolons. Assuming the Round Up kills it then any rhizomes should be inert.

2. and 3. If you don't bring in topsoil then these questions go away. Why do you think you need topsoil? This is like trading the devil you know for the devil you don't know. Your soil can be improved hydrologically, chemically, and biologically. It's pretty easy. If you get new soil, there's no guarantee that it is "right" for water absorption, chemistry, or biology. You can fix your current soil by spraying it with any clear shampoo at a rate of 3 ounces per 1,000 square feet, applying any organic fertilizer at a rate of 15 pounds per 1,000 square feet, and getting a soil test ($25) from Logan Labs (post the results here for a read). The organic fertilizers we like here are Milorganite, soybean meal, corn meal, alfalfa pellets (rabbit chow), and corn gluten meal. One or more of those should be available at your local feed store in 50-pound bags for under $20.

The shampoo will allow the soil to absorb water more freely and go deeper. Water it in with 1/2 to 1 inch of irrigation or rain.

The soil test will tell you how much of what to apply, when, how often. Actually you get that when you post the results here.

The organic fertilizer will improve the health of your soil. If you think the soil is lifeless, the organics will fix that in 3 weeks.

So I'm still trying to dissuade you from adding topsoil. It's a pain in the butt to apply, costly, takes a lot of time, and you don't need it. The power rake will leave your soil ready for planting after you rake up the chaff. Spend your efforts on the shampoo, soil test, and fertilizer. And if you're tempted to use compost, use organic fertilizer instead. The fertilizer costs as much as 15x less per 1,000 square feet to use and is much easier to apply.

I was unfamiliar with a power rake, but I'm assuming it's the same as a dethatcher from my google search. I watched This Old House video where they were using one just to see what it would do. If it were dead grass, which [fingers crossed] mine will be, would it essentially just lop off the top and leave you with somewhat bare ground?

If that's the way it works then that's great, but I suppose my concern would be getting the seed planted. I'm assuming I'll need to actually plant the seed in soil but I may, as a result, simultaneously plant all the weed seeds. Other than the rhiozome issue, would that be not too much different from just using the tiller?

I don't mean to be argumentative, just trying to figure out a plan. One thing of note is that I own a tiller but would have to rent a power rake, so I only ask because I can save some bucks.

Thanks again for your help.

Here's what power rake blades look like:

See here towards the bottom on what it looks like when using a power rake:

http://forums2.gardenweb.com/discussions/4020257/j4c11s-fall-renovation-and-overseeding?n=32

See here what it looks like when you use a tiller:

http://forums2.gardenweb.com/discussions/4123150/lawn-soil-question-for-new-grass

You do not want to use a tiller.

I wish the power rakes & dethatchers around here were equipped with those nice sharp blades! All I've found locally are flails or Spring tine units.