Hello, great question! Rammed earth does not necessarily mean the whole house is fully or partially underground. I like to think of rammed earth as a structural solution and performs the same function as a concrete foundation wall. With that said there are many examples of rammed earth construction typically in warm climates like South America that use a technique of packing water, earth and other aggregate to create a concrete type mixture (https://www.firstinarchitecture.co.uk/rammed-earth-construction/) that can be used as building blocks for the structure. This technique qualifies as rammed earth even though the earth is not technically rammed against the structure.There are instances when say, one or two sides of a house are completely pushed up against the foundation wall. This can be done for many reasons, for example the house could be in a very hot dry climate and burying it under ground will lower the temperature inside as well as, block harsh sunlight.