Many earthbag builders are fond of curved houses. That’s great because earthbags readily lend themselves to curved shapes. But what about the roof?
Thatch roofing is one good solution, depending on your climate and local codes. Here are a few links to get you started.
This is clever because it saves lots of time. The pre-made panels are 2.1 meters long.
Thatched Roofs: An Introduction, an article that discusses the three main thatching materials in use today.
Fijian thatch panels
I like these because they’re flexible and would work great on curved roofs. Here’s a pic.