Steve,
Thanks again for taking the trouble to reply in such detail…I really appreciate it and it’s a great psychological boost to know that an expert is considering my problem! Although I did understand you to be telling me to put wallboard _between_ outer structure frame members, I had nagging doubts that I hadn’t got the message. I now understand perfectly re: 2 x centers of mass, 1 x airspace. ‘Fibro’ is indeed nailed on the outside of a conventional wooden frame. When I removed the crude Masonite-type lining from all walls (building had been used as teen/granny flat by previous owners), I found the now exposed frame timber had considerable termite damage, although not active…someone must have eradicated them a while ago. This will necessitate my replacing structural members in several places, but easy enough. My concern was that the creatures might attack again, although I’m digging trench around building so soil not in contact with bottom timber as was before. Thus I was reluctant to put internal lining on again, and hence the ‘ant-patrol’ strip.
The fibro is in very poor condition, with cracks and holes…far from hermetically-sealed, and bits of daylight visible all over the place. I considered replacing it all, maybe I should, but I am already replacing about 50% roof area with new corrugated ‘zincalume’ metal sheets, and if I put up the budget again, my wife might disown me!
However, if that would be the best way to go, so be it. Stucco good idea, but fibro so old (at a guess 45 yrs), might not be worth it. Was planning to just replace the obvious cracked or missing bits, but even when done, although building (amazingly) keeps water out, is and would still be as airtight as a sieve.
After reading your first reply, was hoping that putting wallboard between frame cavities would seal it despite leaky ‘skin’, if caulked sufficiently. Was planning to possibly wrap this wallboard in polythene sheeting in case fibro ‘sweats’ water through into it. But maybe caulk wouldn’t stick to the polythene. Since outer fibro skin really is so un-airtight, perhaps wallboard on inside of frame? (and presumably either way, under rafters too. .all caulked together). I am very keen now on making this outer wall part of the acoustic structure, so that I can utilise ‘walk-around space’. (Even if I in fact loose the ‘ant-checking capability’ due to wallboard lining…what the heck.. I’ll just get a Pest Guy in).
I hope I’m not myself becoming a Pest Guy with this long post
BTW there is actually about 50% more building area available but with reduced roof height, which I believe I could raise if necessary. Just mentioning this in passing.
Thank you again for the advice on caulk. I’m feeling guilty
![Embarassed :oops:](./images/smilies/icon_redface.gif)
Although I’ve read how important the proper stuff is, I confess - I was going to try and get away with cheaper Silicon caulk. I feel suitably chastened and I’ll make all enquiries to get proper stuff in Sydney now, and will definitely use the proper stuff! Also appreciate the Rockwool specs.
Steve, once again, I can’t thank you enough, for your time and expertise. Hope my long and rambling reply doesn’t a) put you or Forum readers into a coma b) bring server to its knees!
F.