You may find cob cottages particularly cute, but taste isn’t reason enough to choose one natural building material over another. Like more manufactured products, different earth materials all have different uses: straw bale is a great insulator, cob is a nice thermal sink as well as one of the easiest materials to sculpt if you’re looking for lots of curves in your structure. Since different parts of the building need to do different tasks, even in the same building you might choose straw bale for one wall and cob for another. Natural building expert Michael G. Smith shows us some of the uses for straw bale, cob, slip straw and…