Tuesday, September 14, 2010

Thinking Clocháns




Patrick McAfee, an author on restoration masonry and an expert on lime mortars as well as traditional dry stone and masonry methods, is leading a group of us this week from all over North America in replicating a small 14 foot diameter Clochán.

Patrick explained to those of us at Monday evening's opening session of this year's Marenakos StoneFest in Seattle that it will be a traditional round dry-stone hut with a corbelled roof, dating back to the 5th century in Ireland. Most of these original dry laid structures were built like round beehive huts, but rectangular plans are known as well. Some clocháns were not completely built of stone, but may have possessed a thatched roof. But this one will be all stone. The walls are very thick, up to 1.5 meters. Sometimes several clocháns are joined together by their walls. Clocháns are mainly found in the Southwest of Ireland, a good example of this kind of structure can be found at Skellig Michael (Saint Michael), Church Island off Beginish Island and County Kerry on the Dingle Peninsula . They were used by the monks following the teachings of Saint Patrick and later his successors continued building in this style in the Scottish Isle of Iona and then further parts of Scotland beyond.



The one we will be building during the five days of the StoneFest has the shape of the curve for the beehive established by displaying the dimensions marked on a 'boom and mast' trammel arrangement which Patrick devised (and Russ Beardsley of Borrowed Ground LCC cleverly erected beforehand) where the height of the mast (measured in numbered intervals of 3 inch vertical jumps) corresponds to numbers on two 'booms' showing marks where both the inner and outer diameters of the wall extend.


Both booms swivel freely in a circle around the pole. The pole will be removed when the last course goes on and then a huge cone-shaped capstone (made of limestone) be placed on the top. This beehive capstone is being carved this week while the structure is being built by carving students under the instruction of Bobby Watt's son Graham who is a restoration mason in Ottawa Canada.


The stone material being used in the Clochán will probably be a combination of large chunky granite (some of this has already been installed near the bottom to form the base of the hut on Monday afternoon) as well as an interesting grey crunchy basalt to be used mostly on the inside (described by one of the masons as a 'young basalt' ) with quarried sandstone on the outside gradually worked in more and more towards the top.

The contour of the Clochán changes slowly at first, but the curve becomes more pronounced nearer the top and this will require thinner and thiner sandstone slabs to accommodate the angle the corbelled roof as it steps in.

2 comments:

  1. John- Nice blog. Just noticed a typo identifying my company. It is Russ Beardsley of Borrowed Ground LLC. What an amazing structure

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