I know very little about termites, but would like to pass on an idea I heard in Australia. The concern was that the termites might bore up through the cob and get at the wood in the frames and the roof. One suggestion was to place termite mesh through the wall with tin strips welded or soldered to the sides, protruding out of the wall about 3/4 of an inch both inside and out.
Termite mesh is a heavy duty mesh available where termites are a problem. It has holes too small for the termites to get through but will allow the walls to breathe. The solid strip of tin makes it easy for the home-owner to see whether the termites have built their own little cob tunnel over the tin. The tunnels can simply be knocked down to discourage the termites from getting up the wall. Any other ideas?
In Australia, I talked with an old friend who lived in a mud brick (adobe) home that she had built herself and had been living in for 12 years. She said she had a problem with silverfish (little destructive moths) breeding in the walls and eating holes in her books and clothes. She hadn't found a nontoxic solution. If any of you have some tips you would like to share about this, please let us know so we can include them in another edition of this book. Thanks!
Planning things in advance always saves work, so think ahead. If you know you'll be adding on later, build the beginning of the foundation for the future addition where it attaches to the original foundation. This way the foundations will be tied together well. Put in the door frame that will access the new room. You can either hang the door or temporarily board up and insulate the opening.
As you cob the surface where the addition will one day be added, partially bury sticks and leave them sticking out into the future wall's location.
You can also leave keying holes in that part of the wall. Where walls are protected from the rain, you can leave a stair/step with sticks and holes.