I want to build an exterior masonry chimney for a log cabin and since the logs do not make for a smooth wall I was wondering what, if anything, I should put between the chimney and the log wall to seal it from animals,birds,bugs etc. and to make the wall-chimney interface look good.
Also, what is the correct method for joining the thimble(coming through the foundation wall) to the flue liner? Is it just a butt joint with mortar filling in the holes(joining a round thimble with a rectangular flue liner)?
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Traditionally, the fireplace and chimney were built first (of stone), and the log ends scribed to fit it. For you to fit the chimney into the house wall would obviously involve cutting a big whacking hole in the cabin, inserting 2x runners into chainsawed dadoes cut into the ends of the cut logs, and laying up your brick against that. 'Caulk' would be done with the same high-chalk mortar used to chink the logs.
If that's not within the scope of your game plan, I suppose you should just use chinking mortar between the brick and the logs. Or, you could cut into the log faces 1½ inches or so, set the chimney into the wall that much, and chink as needed to fill the remaining gaps.
I can't help you on the thimble joint question; maybe one of the other boys with more experience in open fireplaces can address that part of your project.
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
doby,
If you have studied as many old log cabins as I have you'll notice that the one thing that always seems to happen to them is the chiminey pulls away from the cabin over time.. The heavy weight of stone work setttles and the relatively light cabin floats above it.. Thus it's critical to have enough foundation to handle the weight under the fireplace relative to the cabin.. not easy to calculate!..
It is far safer to have the whole stone work and chiminey inside the log walls completely and then every time you reshingle the roof you can deal with the settleing relative to the rest of the cabin..
In addition you gain because heat radiated by the fireplace isn't wasted outside, rather it remains inside to provide a soft gentle heat long after the fire goes out.. Further the cold from the outside is easily transmitted indoors (since there is no real thermal break in stone)
The ideal placement really is where our forefather put it.. in the center of the house..