As the season shifts, thoughts turn to re building a chimney breast, unique to the Mountcharles area of south Donegal in its use of sandstone flagstones.
As a local man once said – ‘If there’s a thran way to do things – we do it.’
Consisting of five flags, the largest rests upon buttresses of cantilevered stone. Each subsequent flag sits upon a couple of long, narrow tie stones, and are tilted to be slightly outward slanting. The thresher byre gable (above) shows gaps between flags which have been slathered with cement after losing their original masonry.
Looking at a similar construction (above) we see some surviving small stones used to close gaps between flags, but in conjunction with the fire’s heat these stones were vulnerable and could work loose. 
An alternative method was to cut a niche into flag corners thus dispensing with the gap. In the above chimney only the smallest flag remains, and commonly this was cut with corner slots. However it was a more rare undertaking for large, valuable flags to be jeopardized by cutting. (Note the curved cap of lime mortar which would have embraced thatch on a ‘hipped’ roof.)
Workmanship varied but the homes of quarry workers show expertly cut large flags. The above example has three corners notched and belongs to what was once a very fine long house.
Folk who lived in such dwellings recall sharing the hearth with a number of crickets – insects of about 2 inches long and light brown in colour. ‘Píobaire an teallaigh,’ which literally means ‘the piper of the fireplace’ or ‘píobaire gríosí’ which means ‘the piper of the embers’ – their chirp song filled the rooms each evening. A lucky house spirit that takes away it’s luck when it leaves – we hear cricket song but rarely since the demise of our stone cottages.
The sandstone of the Mountcharles region lends itself to cut flags hence a natural choice for chimney construction in proximity to the quarry.
While reading the excellent book ‘The Disappearing Irish Cottage: a case study of north Donegal’ by Clive Simmons & Seamus Harkin – I note a similar style of chimney flue was built from the local Roshine slate.
I’d be very interested to learn if there are other Irish counties or indeed other countries, where flagstone flues are found, or is it characteristic only of the thran hills of Donegal…
limewindow 
I can’t imagine how those massive flat pieces can be lifted into place in such cramped areas, Are you able to use anything other than muscle power?
Allan these skinny flags are not heavy, as much as awkward to maneuver. Cutting the notches and ushering a proper fit with the tie stones is the real expert job. Very sturdy scaffolding is sourced – and true the digger made short work of lifting floor flags, but that was 30 stones. ‘Cos of the pure muscle on Créhan, Keeney and those FAS boys, it will be like dealing a deck of cards, casting those flags up on that gable.