Friday 26 April 2019


The papers from the preparation of BUILDING BROCHS, see -, were lying around as the coffee was poured the next morning; the pens were still there. One soon discovers the value of a mess. The eye looked at the preliminary round house plan again: might the posts be erected first? A sketch of the posts was made. Yes – it seemed likely: the centre could be identified and the hexagon marked out on the ground with a peg and a length of string. Then the holes would have to be dug and the poles erected, aligned and braced. This could all be done without the encumbrance of the walls that not only limited the construction area, but also restricted access to one location. The idea had practical merit.

Typical round house plans

The timber frame was drawn as it might look. From this start, the set out of the circle for the stone walls could begin. The timber frame became a permanent reference marker for location and orientation. Pegs, string and a template was all that was required to mark the circle. This could be managed progressively too, as the wall was constructed. It would be difficult to maintain the markings of the set out of the complete circle on a building site. With the core identified, the whole round house was able to be set out piecemeal. Once the walls had been erected, the roof could be finished, linking the walls to the central frame conically. It made practical sense: the challenges of building sites do not change with time. It is an environment in which precise set outs have to be achieved in the context of a dirty shambles. Might the broch have started similarly?

Typical broch plans

The rough sketch for the process of setting out concentric circles was picked up and perused. The pen began its scribblings. Peg locations could easily be marked out after the erection of the hexagonal frame that defined the centre. Parts of the walls were drawn in; a section was sketched. Once the braced frame was in place, the profiles of the walls could be set up radially on the ground and the walls begun. Once the first profile height had been completed, the first lift could occur. This would entail temporary scaffolding: the pens scrawled out a possibility. Inside and outside would have to align so that the profiles could be supported. The first lift would have the solid stone base as the support.

Stones could be lifted up to the working level of the scaffold. Once finished, the first lift would have reached the scarcement level. The scarcement would have been installed at this time as projecting slabs of stone; then joists could be put in place: but! - the scarcement needs mass above it for it to be a solid, stable, load-bearing element.* A temporary prop is needed to support the scarcement or the joists until the upper inner wall has sufficient mass to counter the floor load. Here one thinks of the temporary props used for concrete work; these stay in place until the concrete has cured and gained sufficient strength - usually about 28 days. Once the joists are in place, the next set of hexagonal poles could then be positioned. These would have to be joined so as to maintain the geometry of the hexagonal reference used for the set out. The doodling seemed to be giving substance, clarification to some lingering unknowns, even revealing new issues that had never before been noticed.

The beginnings of yesterday’s broch section scribble was picked up. Why not sketch in the parts here to consider the impacts? Ladders were drawn on the timber frame and a different roof was drawn in: maybe? A red pen was picked up to consider the scaffolding. Temporary scaffolds would be required inside as well as the permanent framing. These platforms needed to be co-ordinated with the temporary external scaffold to provide support for the wall profiles: but what holds the profile up between the walls? The stone ties could do this. Ah! Each lift in the scaffolding could also mark the position of the bridging stones that would be installed along with the top stones of each lift. Interesting.

The progressive lifts of the dry stone work are illustrated in this cross section.

The piles of stones were marked in to test the idea. Yes, the rocks could be placed at the working levels as things progressed. The space inside the hexagonal framing would be available for lifting, as well as for general access: but by this time, the broch entry would have been formed, limiting easy access to this lift area. Maybe the stones were transferred from the massive external piles with a lifting device that could deliver stones to the working platforms externally, and swing them over the walls onto the central, internal scaffold. This appeared to be a more practical and flexible arrangement. The floor joists were drawn in on yet another scribbled plan to see how they might set out. The radial pattern would concentrate the timbers at the hexagonal frame, and limit the minimum spacing. This seemed not to be a problem; but what material was used for flooring? Timber planks seems to be the first guess, but was this wood available? Might mats and clay have been used? The material would finally define the required joist spacing.*

Diagrammatic structural diagrams do not clarify or resolve thinking on brochs;
they only confuse, confound, and complicate.

The more one scribbled, the more things seemed to come together, or be further challenged. Everything appeared to confirm that the building of the broch started with the erection of the hexagonal timber frame that was the place marker, permanent set out reference for the circles, and the vertical axis for the alignment of the height of the walls. The system seemed to pass the building site test, and even offered a solution to the handling of the massive quantities of stone that were required at the various working levels. The permanent portions of the interior scaffold could be installed progressively, with the temporary scaffolding coming and going within this main framework that was supported at its perimeter by the scarcement, and centrally by the hexagonal frame. Once the dry stone walls had been completed, the lower temporary props for the scarcement loadings could be removed.

Could the lower space have been like the byre of the black house, dug out every summer?
This space could also be seen as incorporating the equivalent of the store area of the black house,
with the living space above rather than being parallel to it.

The set out plan diagram was returned to. Of course! The building process would have been started with a ceremony. Even today we have the laying of the foundation stone. One could envisage the marking of place, the axis mundi, the symbolic centre of the earth – the centre of the hexagon – with fire and smoke. Australian aboriginals have a smoking ceremony to cleanse space and place. One could imagine a priest or a shaman involved in a ceremony celebrating the beginning of this great enterprise, drawing the hexagon, placating the gods and blessing the land. It has always seemed that the lack of any spiritual explanation in the broch studies has been a fundamental weakness. To ancient man, the whole world was meaningful, symbolic. The building of the broch would have involved a spiritual celebration. Might the hexagon have meaning; the numbers 3, 6, 12? The Star of David was never just a Jewish symbol.#

The meaning of the beginning would always be the anchor of place; would always be there for remembrance, defining the connection between man and God: earth and heaven – the mystery of life itself. The axis mundi was there as nothing but everything, shaped by the hexagon. The hearth would become the permanent core, the anchor of life and space, with smoke rising into the heavens creating the ephemeral physical link between life and its enigmas. Tradition has always spoken about the importance of remembrance, of the importance of returning to, of remembering our origins. The beginnings of the broch would remain as a central reference, not only throughout its construction period for set out and scaffolding, but also for the whole life of the place, there for the everyday, for continued renewal of the spirit and the placation of the Gods.

The efforts to interpret broch functions must to go beyond the search for mere practical purposes.
They need to consider the spiritual context, and its symbolism.

Compare this roof with new 'iron age' roof images below.

Slowly, as one doodled and thought about the broch, the practicalities of construction and life became intertwined with things real and tangible; mystical and spiritual. This coherence resonated with reality: we cannot overlook the mysteries of life and the role they have played, and still play. Architecture has always involved these; but today we seem to have forgotten this. One only has to flick through Sir Banister Fletcher’s A History of Architecture to see the thousands of historical structures rooted in the search for and celebration of meaning. Brochs could not have been removed from this involvement.

Today’s ponderings started with the scribbles on the round house plan, so this doodle was looked at again in order to test the theories revealed by the other scribbles. How might the idea of the priest/shaman/symbolism feel with the construction of the round house, the precursor of the broch?

The scan of Mousa broch showing its axial reference.

The pen was picked up again and wandered its way around the hearth marked on the plan. Yes, it would be like this. The point would be marked on the ground and the hexagon set out, just as we have ground-breaking ceremonies; the fire lit, the smoke rising as the blessings were chanted and danced into reality: real place was being marked and blessed to become the centre, not only of a structure, a permanent marker for its making, but also for life itself. The idea made wonderful sense in the simplicity of the round house. From this mystical centre, the hexagon could rise to become the markers for the circle, an enclosure both symbolic and real, reconciled by the structure of the roof. The void of the axis - the untouchable, unspeakable; that which cannot be named - is there, revealed as a location within the geometrical forming of the hexagonal frame, the hexagram, and enhanced by the conical form of the canopy. Daily life would have centred on this core, the central hearth, from which smoke would rise as the axis, co-joining man with spirit, even as food was being prepared. Every activity would relate to this place, just as it would in the broch. The layering and inter-relationship of logic and dreams in this theory enrich it and give it substance – poetic credence.

What we call the beginning is often the end. And to make an end is to make a beginning. The end is where we start from.
T.S. Eliot

As an aside, for a discussion of the symbolism of the hexagram, see:

Photo: Duncan-Enzmann, solstice symbol, Altamira Cave, 16,500 BC

 With roots in prehistory, the evolution of this familiar symbol can be observed
with the following illustration of the winter solstice symbol, summer solstice symbol, and then combined solstices.  

Winter Solstice -Spring Equinox-Summer Solstice-Autumnal Equinox-Winter Solstice

Illustration from Solomon’s Power Brokers

As with most symbols, the hexagram gained layers of meaning as it flowed through time, adapted and adopted by cultures, coming eventually to symbolize the union of opposites: male and female, fire and water, error and truth, active and passive, darkness and light, ignorance and wisdom.

It is for this reason that it makes no sense to interpret the scarcement only as a support for scaffolding as Brian Smith, (Shetland Museum and Archives), has argued. One would require temporary scaffolding to support the support for temporary scaffolding. The scarcement must have had another purpose. The proposition here is that it supports the permanent internal scaffolding/framing, keeping the perimeter timbers out of the lower ground space that has been zoned as a service space, a 'wet work area,' involving perhaps animals, waste, water.

27 APRIL 2019


The broch building site: the beginning.

The roof is difficult to tie down - see below.
Note in report below that the smoke filters through the thatch.
The black house relied on this to keep the vermin out of the roof: see - 

The wall profiles can easily be set up radially.
They can also be used to set out the concentric circles from the set out of the inner circle.
This process avoids the need to work over any dry stone wall for set outs.

Profiles remote from the elements being set out are still used today.
The central hexagonal frame can be likened to the 3D profile of the broch.

The joists and fire - symbolically central.
The joists can put in piecemeal to act as scaffolding for the work at whatever stage/location.

The roof can be tied down in the round house, (as below), but not to dry stone walls.
Further tie down/bracing/stiffening elements are suggested.
Note that the roof can be erected and maintained from the perimeter, much like the black house, see:

The temporary and permanent scaffolding.
Work can proceed on different stages in different locations.
The central hexagonal permanent structure provides the fixed reference point for all elements.


For images of a new 'iron age' round house, see:

The report says that the round house is '30 metres' in diameter; maybe it means 30 feet? The roof timbers are said to be from 28 foot lengths. Mousa broch is approximately 20 feet - 6metres - in diameter inside, (50 feet - 15 metres - outside at its base). The images give some idea of the technology and lifestyle of the era as we understand it.

If the rafters are 28 feet long, and the roof is 45 degrees pitch, then the inner diameter is close to 30 feet.
The roof would be approximately the size that would fit Mousa, to sit on its inner twin wall.
Note in the comments above the difficulty in fixing the framing to the dry stone wall.
This round house has no inner structural framing; it is tied down to the outer ring frame.
Traditional round houses do have inner posts.
Brochs would need inner framing not only for a structural profile reference, but also for floor spans.

28 APRIL 2019

Maybe everything to do with brochs is vague and uncertain?

This notice on the door of the Carloway Broch Centre tells visitors that the centre is:
10am to 5pm  (or thereabouts)
Monday to Saturday
Admission Free

The scarcement of the Carloway broch is clear, but it is uncertain if it was ever a continuous row of projecting stones, or a series of separate corbels. If it was the latter, these could have carried a segmental bearer for the joists to sit on. It does not change the purpose of the scarcement as the projecting stones still require the mass above to make them stable.

25 February 2020

19 October 2020
Perhaps peat could have been used. One of the oldest houses on the island of Unst in Shetland, a cottage at Haroldswick, had an internal wall constructed out of peat. Peat is plentiful; it dries to a hard mass; and is a good insulator.