Handily Stepping Out

Beehive Hut in Washington

Dry Stone Cabane in Ontario

Corbelling is a structural method of jutting stones or bricks out from a wall in ascending courses to support more and more material above. Each stone is placed so that the bulk of the stone is deeper into the wall than the part that is projecting. In this way a lot of weight of the building can be suspended over an open space.

In the case of dry stone huts, such as the beehive recently built in Washington and the cabane in Ontario, corbelling the stones towards the centre of the interior space defined by the circular walls eventually creates an enclosed stone ceiling and support for a roof. There are various methods and formulas for doing this. Obviously stepping out too soon or too far each course can make the structure unstable. Stepping out too slowly involves using a lot more material than necessary and makes the structure disproportionately tall.

The beehive corbeling involved long stones straddling the inside angle of another pair of corbelled stones below along the circumference of the opening.The outer corners of the stones are fully supported and it is only the middle overhanging 'delta' of the stone that projects out.

The corbelled stones of the Canadian cabane, on the other hand, have edges (and corners) that project unsupported but with more of their interior length acting as a counter-weight with wall material simultaneously placed on top so as to weigh down each course of corbelling below. The inside corners of these stones touch in a circle at the interior of the structure and the stones slant out and downwards into the wall so that any tendency for the corbel stones to slump is counteracted since each circular course of corbels would have to spread (and the open space get larger) before any stones could begin to drop.

In both methods of construction a functional roof can be created without having either to build a true arched vault or having to use wooden beams.

It is fascinating to see stones used in ways that their weight and mass seem to contradict the force of gravity.

Handing down a tradition.

The amazing dry stone beehive hut project that was recently completed by those of us who participated in this year's Marenakos StoneFest near Seattle is a structure not unlike the vaulted roof Cabane we constructed in 2008 at our annual Canadian 'Rocktoberfest'. The French version of the Irish clochan is also a traditional round building made completely of dry laid stone and various historical examples of these buildings can be found in many parts of southern France.

The cabane that members of the Dry Stone Wall Association of Canada constructed 2 years ago had dimensions that were slightly wider and taller and the domed ceiling actually corbelled in using medium sized flattish stones set carefully in place so the tiled surface of the roof also shed water.

We finished the roof during the festival held near Cobourg, Ontario, Canada while nearly 1200 people came to watch over the three days of the Canadian Thanksgiving . Above are two photos comparing the the beehive hut and the French Cabane at similar stages of construction.

(This Thanksgiving October 8-11 our Canadian festival will be celebrating its 7th year where wallers from all over the world gather and show off their talents. Amongst other demonstrations and presentations during this 4 day event, a crew of professional wallers will be building a dry stone 'footbridge' along a forested trail at Landon Park on the 1000 island parkway off the 401 between Toronto and Montreal.)

Tomorrow I will post photos of the two structures as they stand completed, and also post shots of the inside stone ceilings of both the beehive and the cabane.

Handy Cap Stone

Graham Watt put a lot of time (nearly four days) and a lot of skilled handiwork into changing the shape of a huge square chunk of limestone into an impressive cone cap for the clochan that StoneFest participants built last week near Seattle Washington. Christopher Barclay another Canadian and several other Americans also put in hours of hand-chiseling on the large white block to coax a geometric curve domed shape out of the stone. The shape had to be the exact dimensions to make a final seamless transition from the dry laid contour of the rest of the hut up to the peek. And it it had to be finished on time to hoist it on to the beehive structure by Friday afternoon.

It was decided that the final surface of the cap stone should be detailed with the shapes of all the hands of those who were involved in this project. Dry stone wallers, carvers and sculptors in stone traced a profile of their hand on the dome and then they, or one of the letter carvers, carefully chiseled each hand print out. The large white limestone capstone ended up looking like everyone had put their hands into plaster of Paris before it set.

The huge stone was lifted on to the stone hut using a large Caterpillar with a massive mechanical claw, and with the help of many more hands it was eventually lowered into place. Professional sculptor John Fisher is seen here using one hand to guide the stone down onto its final landing spot on the top of the clochan. The 'handy' capstone proved not to be a handicap at all, in terms of finishing the race towards having this magnificent beehive hut project completed in time.

Listening with my hands

For nearly five days a continual beehive of activity went on here in Washington as workers assembled all the stone pieces of an unusual circular hive - a completely dry laid structure known as a Clochan.

Towards the end of Friday the final cap stone went on and the work-bee came to a celebratory end on September 18 at the Marenakos 2010 StoneFest.

The drone of the machinery and the hum of the workers who had been busily chipping and shaping and fitting stones faded away and a new sound could be heard, an even sweeter sound than chisels ringing as the many stones were dressed.

The haunting drone of the bagpipes filled the air, as 6 traditionally dressed pipers arrived at the site and began playing for the wallers who had worked so hard on the project and played too for the others who had participated at this year's StoneFest including the letter carvers and the stone sculptors. After playing a couple of tunes, including Amazing Grace near the entrance of the newly constructed clochan, several pipers actually crawled through the small granite-stone opening and began to play inside the clochan.

It had been a special 'hands-on' week which ending appropriately with a special 'hands-on' moment when we gathered around the structure and 'listened' to the drone of the pipers playing inside the beehive, and placing our hands on the outside, many of us could almost feel the stones singing, as the far away sound of bagpipes seeped through the walls.

Within reach of rightness

There is something about being surrounded by stone. Here inside this chunky enclosure - the traditional Irish dry stone 'clochan' we are building near Seattle Washington, there is this undefinable 'sense of place'. It's something you have to experience by going inside, it's not enough to stand on the outside and imagine what it's like.

There is this 'energy'. A kind of, I dont know what. I don't want to get spooky about it, but there is something that happens. There is this grounding - this focusing of your self with the stone. Even though the structure isn't finished and the roof isn't completed yet, there is already a feeling of 'historic presence', as if the building, just by its mass and structural integrity has claimed it's rightful place in time and space and that it has somehow 'archived' itself and become part of the past, a history that is only felt, but not yet documented.

None of this could be achieved with concrete or phony stone. It definitely could not be reproduced with nonstructural veneer stonework, or any other manmade material. This is a purely natural stone phenomena, which if you're lucky enough, and the enclosure isn't too crowded or too detached and too far apart, then the stones let you know they are in agreement with their proportions. If all these things comes together, when you stand between the walls of such a structure, it wraps you in 'rightness'

Grasping the obvious.

Third day of the StoneFest at Marenakos. The sides to the beehive hut are steadily going up under the careful supervision of Patrick McAfee. The 8 large rectangular stones form the canted sides of four crude window openings. Also note the batter is starting to go in faster to form the signature curve of the Irish clochan.

It is interesting to compare the 'noise' level in this video compared to the previous posting where there are no machines running.

It always amazes me how dependent stonemasons have become on large machinery. This powerful mechanical 'hand' does the job of 8 men lifting these stones into place. Unfortunately there are those of us who didn't come here to watch heavy machinery move stones. Most of us see that every day in our working environment. What many of us came to see and experience was a transfer of knowledge, including a passing down of an inheritance of stone moving skills different to those used on every job site today.

Im just saying.

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.