I dug out all the dead grasses from my backyard after the patio was installed. It leaves about 700 sq ft for new sod. Because of the slope of my backyard I also would like to raise the lawn by a couple inch (approx. 4 - 5 inch) to make it more even for the lawn. There are couple different type of soil to choose from: screened topsoil, 50/50 compost/soil mix, or peat loam. Some sod farm companies recommend 50/50 compost/soil mix, some state that a regular screened topsoil is good enough, or either go for peat loam. It seems that 50/50 compost mix has a lot of benefits (e.g. reduce erosion. breaks up clay soils and so on) but it costs more than screened topsoil. Which one should I use to build this soil foundation before the new sod put on?