Stone & ice – a misunderstood threat to historic stone

Historic buildings and archaeological monuments are periodically subjected to aggressive environmental conditions such as storms, high winds and freezing winter conditions. Alterations in local environmental conditions can impact the microstructure of historic and modern building materials, eventually leading to macro-scale damage such as spalling (the detachment of fragments of material), granular disintegration (powdering) and fragmentation.  Durability testing of new mortars, stones and conservation treatments attempt to predict the stresses of decades of aggressive environmental conditions through simulated accelerated weather conditions. In real-world condition, the concerns surrounding this seasons cold temperatures and snowfalls are more usually focused on what may happen now in the short-term. However, if sudden building failures in the winter months are wrongly attributed to freeze-thaw action simple because snow is present, larger, more serious and costlier problems can be overlooked.

‘Freeze-thaw’ damage is a common form of moisture-related decay of building materials, and a sub-set of how buildings handle precipitation. Along with drizzle, rain, heavy downpours and storms, in winter historic buildings and structures must also handle sleet and show, dew and ice. Freeze-thaw cycles see the transformation of water into ice, and this can exert two types of pressure on historic building materials such as stone, brick, mortar and render. Continue reading


Open House Dublin – Provost’s House

The Provost’s House of Trinity College Dublin which stands at the bottom of Grafton Street is also open to the public as part of Open House Dublin 2017. The building was begun in 1759, and is screened from the street by a walled forecourt, with the former stables now used for academic research, but retaining a covered passage which connects the house to Parliament Square in TCD.

The Provost’s House was initially examined in 1998 at the request of the Director of Buildings, TCD. The aim of the project was to assess the condition of the stonework and the impact of intense soiling on a number of historic buildings and monuments in TCD in advance of a programme of cleaning.  While most of the building was cleaned during this period, the ground floor of the facade and its rusticated wings remained was left uncleaned as the project tested potential cleaning methods and techniques for the vulnerable Ardbraccan limestone work. This included water-based cleaning methods, bespoke stone-cleaning poultices, laser cleaning trials (the first in Ireland) and chemical consolidation. Continue reading

Open House Dublin – Seapoint Martello Tower

This weekend sees the 2017 Open House Dublin event presented by the Irish Architecture Foundation. I’ve had the opportunity to undertake professional research work on a number of these buildings over the years.Today, I’d like to describe conservation research undertaken since 1999 at Seapoint Martello Tower which is open on Sunday as part of the event.

The first phase of research at Seapoint Martello Tower was an assessment of stone deterioration as part of the Stone Monuments Decay Study 2000 undertaken on behalf of and published by The Heritage Council. Following on from this, its coastal location made it an ideal case study to examine the impacts of the coastal environment on built heritage, and it formed part of my PhD research. Stone decay was mapped on the tower and on rocky outcrop, with in situ XRD analysis of the granite ashlar, historic quarry and natural granite outcrop looking at the action of salts of marine origin on Irish building stone. The condition of the granite was examined again in 2010 as part of the Stone Monuments Decay Study 2010 which looked at changes to a representative sample of historic buildings and archaeological monuments over a decade. Continue reading

Intangible cultural heritage in Ireland


Intangible cultural heritage encompasses the traditions or living expressions inherited from our ancestors and passed on to our descendants, such as oral traditions, performing arts, social practices, rituals, festive events, knowledge and practices concerning nature and the universe or the knowledge and skills to produce traditional crafts. Ireland ratified the UNESCO Convention for the Safeguarding of the Intangible Cultural Heritage in March 2016, and Uilleann Piping and Hurling were included on the interim National Intangible Cultural Inventory.

While Ireland’s tangible heritage (buildings, monuments, landscapes, structures and natural heritage) is well understood, the study and awareness of intangible cultural values is relatively new. For many professionals engaged in the conservation of tangible heritage, much of the literature on intangible heritage is found in Continue reading

Staigue stone fort, Kerry

Staigue fort is one of a number of stone forts, related to ringforts and cahers, which have defensive features shared with Dún Aonghasa on the Aran Islands, and with Doon Fort and the Grianán of Aileach in Donegal. A number of these impressive forts on the Ring of Kerry can be found at the western end of the Ring of Kerry, including Loher, Cahergal and Leacanabuile. Staigue fort appears as a circular, dry-stone enclosure wall or rampart, surrounded by a fosse and external bank, with a causeway forming the entrance to the fort. The walls were constructed using internal and external faces of roughly coursed dry-stone masonry enclosing a rubble and fill wall core. The walls show an external and internal batter, so that they walls taper from approximately 4m wide at the base to 2m at the top.  The single drystone entrance passage has three lintels, with the external lintel relieved by another lintel one course above. The interior of the fort has two wall-chambers, and a series of characteristic X-shaped stairways leading to the top of the walls – a feature also seen in stone forts of Donegal.

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Early maps and charts of Ireland

Early maps and sea charts offer a great deal of insight into the past. Prior to the 16th century, mapped depictions of Ireland were part of the culture of other nations. From the 16th century onwards, maps and charts became increasingly more technically sophisticated and accurate with regards to placenames and topography. By the 17th century, the emphasis in mapping had shifted from maps for defence and military campaigns to the plotting of large areas as part of the process of confiscation of land. In addition to maps, a diverse range of charts of Ireland were created from the 16th century onwards. Charts created for defensive purposes often included large scale mapping of ports and anchorages. A comprehensive list of early maps and charts of the Irish coast is provided in Exploring the Maritime Archaeology of Ireland.

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Risks of Mechanical Cleaning Historic Stone


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The removal of soiling from a building can be achieved using water, chemicals, poultices, lasers, and also mechanical cleaning methods. Mechanical cleaning requires the use of force using hand-held tools such as brushes, sponges, scalpels etc. or with equipment such as vacuums, or dry air-abrasion. Mechanical cleaning can be low-impact, and is often used where water or chemicals are not suitable. However, stone can easily, immediately and permanently be damaged by mechanical cleaning.

Abrasive cleaning systems direct particles onto soiled masonry in a stream of compressed air of between 1.5 and c.7bar.  The systems work by Continue reading

Drone Surveys of Historic Buildings

Drones, or unmanned aerial vehicles, are useful tools for surveying historic buildings and structures, as well as assisting in diagnosing building failures. Drones can also be useful for archaeological research and of ruined buildings and their surrounding landscape.  Drones are small, portable, and able to hover and operate in confined spaces, yet are powerful enough to carry DLSR still and HD/4K video cameras for survey work, as well as lidar and terrestrial scanners. For historic buildings and heritage sites, drones offer high-resolution  imagery and data which can be used for monitoring, recording, presentation, interpretative display, surveying, and mapping. Continue reading

Green Fort Conservation Plan


The Green Fort is a seventeenth century earthwork fortification in Sligo on the west coast of Ireland. The fort is an archaeological monument, and one with the highest level of legislative protection. Currently, a conservation plan is being developed to determine how best to protect, manage, interpret and present the


The Green Fort is the largest and strongest of three spear-shaped bastion forts erected in the seventeenth century to protect Sligo town. These forts were the still-extant Green Fort and Coney Island Fort, and the now-lost Stone Fort which lay beneath Sligo Town Hall . The Green Fort appears to have had two or possibly three stages of development, and then passed into a long three hundred year period of abandonment. Continue reading