I am in Tasmania, a southern state of Australia. My soil is clay (although not heavy clay) - grass will typically grow OK on it.
I have sprayed the area I want to grow new grass with glyphosate - as soon as everything dies off, I will be looking to sow new seed.
I have a rotary hoe that I can use if needed.
I will be bringing in new "lawn mix" topsoil which is just a topsoil with added conditioners, fertilisers and composts for growing grass.
What depth should I use over the existing soil base, and do I need to hoe the clay before I put the new topsoil down?
I have heard figures ranging from between 50-150mm, and I am working with a very large area, and don't want to purchase more topsoil than required. I'm also very open to any other advice you might have to share to ensure the success of the new grass.