fireplace/oven/lime putty

Questions and answers relating to houses built in the 1800s and before.

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fireplace/oven/lime putty

Postby killian on Sun Dec 18, 2016 6:32 pm

I have an 1840 greek revival which has a stone and brick fireplace with an adjoining beehive oven.
[img][img]https://c1.staticflickr.com/6/5577/31690192616_1d9789ec00_b.jpg[/img]oven:fireplace, 12:16 by Michael Fogg, on Flickr[/img]
There is a flexible metal chimney liner and a woodstove occupying the fireplace. The liner bypasses and blocks the flue for the oven.
I'd like to restore both the fireplace and the oven to their original functionality- I'm doing the work myself. I make concrete furniture professionally and I do masonry recreationally; I think it's reasonable to expect that I can handle the job provided I know the correct protocol.

The oven's flue leans into the main flue (flying butress style). The two flues converge about 7 feet above the floor. Here's the view from the rear, all the masonry recently exposed during demolition. This masonry was not meant to see the light of day, instead it was designed to be buried behind plaster.
[/img]Imagebeehive, rear 12:16 by Michael Fogg, on Flickr[/img]

Given the age of the brickwork and upon examining the mortar I'm sure it's lime mortar and not Portland based, which means it ought to be repaired with more of the same, as Portland based mixes will be too rigid. Parged smooth inside, re-pointed outside, correct?

The main difficulty will be parging the inside of the two connected flues because there is no access, no way I can reach my arm in there and get to it with a trowel (even one with a very long handle as there's no clearance). I can fit in the smoke chamber ok but above that I'm just too fat to fit...

I read of systems where a cone shaped plug is gradually drawn up the flue as the parging material is dropped in there, but I've never heard of this method being used with lime, insteade it's usually a refractory made with CA cement, and/or Portland, clay, ceramic (a thin rendering system from the UK I discovered), etc. all of which will be too stiff and may cause the system to crack, at least so far as I understand. Same problem with inflatable balloons used to cast chimney linings. Besides, the entry point for the oven flue presents a problem as I don't want it blocked off.

Perhaps another method might be to selectively remove three or four bricks at a time, enough to reach my arm in there, every three feet or so, parging the chimney in sections and working my way up. It's only a story and a half and it's all exposed right now during the demolition process. I've looked for documentation for this procedure but haven't found it yet though...

Is the only solution to dismantle and then rebuild?
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