You can absolutely have windows and doors in a cob house.
Putting a roof on a cob house.
You would place a bond beam at the top of the cob wall ideally concrete and rebar or alternatively airplane cable connecting all the members of the roof in one big circle they way the roof is designed is to act in compression while exerting force on the bond beam which will act in tension.
For a first time builder a yurt style roof like cyric30 suggested would probably be easiest.
Learn about the pros and cons of each material in this excerpt taken from roofs.
Cob structures can be used as homes chicken coops barns and even smaller ones for ovens.
The main approach here is to have a solid timber act as the header for the span of the top of the window or door.
Cob house construction is an ancient building technique using lumps of earth mixed with sand straw and water.
The roof can be constructed the same way and many are made with a flowing.
Windows and doors in a cob house.
It will comprise of 6 dwellings and the main house which is 2 storey will be 80 cob.
Many cob homes are made with curves bumps and flowing lines.
Basically have a big beefy piece of wood at least 6 inches thick and go for as wide as the wall.