Wow, good bodge-job! :)
I never get tired of telling people you live in a house in the middle of the woods that was sold to you as 'unliveable,' lol. Though actually, when ever I see pictures of it, it looks quite cozy! ^_^

Have you ever heard of the 'Foxfire Book'? It was collected in the 60s by ethnographers in the Appalachian mountains who were concerned that a lot of the techniques that were part of the traditional 'hillbilly' lifestyle were dying out. Its got *loads* of information on log-cabins, building traditional stone & cob fireplaces, making moonshine.... amazing book!

I wonder about your bad log... if it is damp and rotten it might be because it is in the corner - I think I read somewhere that corners and angles in rooms are often where condensation gathers first and starts to cause rot. Well, as long as its not spreading through the log, I guess its okay!

So do you just have the frame of the entrance hall exposed to the weather? Have you covered it with tarpaulins or something? Or did you just decide to tear the whole extension down and replace it from scratch?