I got frustrated a couple years ago with our georgia red clay and had a really bad growing season the first year I lived in my new house. I decided that I would make a raised bed for the next season so I didnt have to deal with the clay soil anymore. Made the bed out of 2x12 pieces of untreated pine at the end of the summer that I had the failed crop. I went around to every bush and tree in my yard and raked out the dead matter beneath them and piled it up into my beds. Next I purchased about 16 cubic feet of topsoil and mixed it in with the decaying leaves. After this I put grass clipping over the top of my mixture and left it alone until the next year. I have been doing this for about 3 years and I have had to replace several boards due to the rot caused by the composting soil, however each year I was able to grow a more successful garden in the raised beds. This year the pine had become extra rotten so I decided to rip it all out and rebuild with some hardi plank. When I ripped it all apart and raked the soil off to the side I noticed that the ground beneath my bed was no longer red but was instead dark brown rich and loose. I was so shocked to see this!! So this year I moved my raised bed over to the left exactly one space from were it was. I can now till and farm the land were the raised bed used to be so for the first time I can grow a garden twice as big. I think that if you sacrifice a big garden by having a small raised bed you can eventually have a huge garden because the raised beds will break down the clay ground on their own. If you move the bed every couple of years and keep the old spots composted you will always have great yields.

I'm from Illinois, so I've got certain expectations of what topsoil should be. My idea of what topsoil should be is very similar to what my garden soil now looks like, after 9 years of composting. I always thought soil was black, but when I moved here, I learned that it is often yellow. I bought a load of topsoil, and it turned out to be clay mixed with pea gravel and shredded wood. One thing to note is that with our conditions, manure isn't always a good choice as an amendment. Due to the need to irrigate, salinity is a problem, and manure tends to exacerbate this. I would be inclined to bring in as much compost or even shredded trees as you can. If you can find a tree service, they might deliver shredded trees for free (it saves them paying to dump them). You could probably even bring it in now and just spread it on top of the soil. A lot would break down before it's time to plant the grass, and what doesn't break down would work into the soil more easily after a few months of letting it decompose, letting the worms work the soil, etc. Since you haven't planted the grass yet, you almost can't overdo the amount of compost, shredded trees, etc you bring in. Once you have a lawn in place, you shouldn't apply it more than about 1/2 inch deep (1 cu yd will cover 648 sq ft to 1/2 inch). As far as the hardiness zones go, I've learned to err on the side of caution. The problem is that the hardiness zones are based on the lowest winter temperature. It got much colder in the winter in Illinois than I've ever seen here, but the last snow was usually in January or February, and the last frost was usually in March. We usually had our garden fully planted by the beginning of April. I've learned that the only reason to plant before mid May here is if you like planting repeatedly.

Clay soil is a beast to dig but it contains lots of nutrients, especially the black clay. When I gardened in black gumbo, I used a lot of soil conditioner/landscaper mix on top of the clay and kept it mulched and fairly moist. To my surprise, a few years later, I could easily dig with a hand trowel in the beds that I improved like that. Are you trying to overcome the PH with greensand? Another useful tip when excavating for a shrub or tree is to spray the area with soapy water a day before digging. I'm not a chemist, so cannot state why this works but something happens to release the clay particles and it's easier to dig and doesn't stick to the shovel.

A clay roof would be so charming here! A metal roof could look really good too, it's also common on stucco homes in the southwest. IDK, but it might be easier to maintain too. If you went that route, I'd recommend terra cotta, dark brown, or maybe even blue. (Or if you're made of money, a copper roof and let it turn green.) I have a metal roof and one lesson I learned is that it's super hard to get a vendor willing to install anything -- nobody wants to be responsible for cutting into it. You might run into the same issue with clay. So if you think you will need to add skylights, roof vents, etc, have it done when the roofers are there!