What are some different roof building techniques for earthbag homes?

Im not sure if im going to do a square home or a roundhouse but what are some different ways I can build a roof? Im not going to have very many tools (could buy some if needed).

For what climate? What are your local resources?

You can do round--center pole, center ring (yurt style), dome or reciprocal.

For square you have all the normal shingled methods plus things like hypar.

Materials--thatch, rubber membrane living roof, tile, tin, ferrocement, coated canvas.

I know there are a bunch more, but I can't think of them right now.

Im going to be in northwest Arkansas. Im most concerned with keeping warm in the winter then cool in summer. Im only going to have one or two other people to help me as well. Thanks for the info so far!