Church Roofs Research Articles

The analysis of long-time-exposed tars from wood shingles from church roofs and facades in mid-Sweden

ABSTRACT Poor condition of roofs in terms of decay of shingles and loss of tar-based surface treatments has been revealed in a number of churches at various geographical locations in mid-Sweden. The condition of tars obtained from shingles of selected churches in mid-Sweden were analysed and obtained data were compared with geographical locations of the churches. According to gas chromatography-mass spectroscopy result, dehydroabietic acid was the dominant compound found in the exposed tars from the churches except in church of Malung where similar amounts of retene was found. Oxidised resin acids were found in exposed tars from the churches but not in commercially available pit burned tar. Tar from church shingles had higher char residues than the pit burned tar which was totally consumed when heated under nitrogen gas up to 750°C using thermogravimetric analysis. Scanning electron microscopy with energy dispersive X-ray spectrometer analysis revealed higher amounts of silicates in some exposed tars; however, these compounds constituted only a minor portion of the organic matter in these specimens. Based on the data obtained in the study other factors rather than simply geographical location of churches seemed to be of importance to explain differences of the investigated properties of the church tars.

A review of Scandinavian research on medieval church roofs

The remarkable clusters of preserved high medieval church roofs in Scandinavia have been known since the early 20th century but surveys aimed at mapping and document these structures began first around 2000. The author reviews the State of Scandinavian research and presents recent and ongoing survey projects in Swedish dioceses. These cross-disciplinary projects have enhanced the value of historic timber structures as archaeological source material. A reading of craft techniques and tool marks provides insight into the work of the medieval carpenters. An example is presented of how a structured survey followed by moderate cleaning shaped a basis for maintenance and restoration in compliance with international principles.

The Pure Sky and the Eternal Return: Zarathustra’s Affirmative Atheism

Abstract Zarathustra initially describes churches as the stale caves of world-denying priests. However, following his encounter with the eternal return of the same, Zarathustra overcomes this resentful atheism. The pure sky that Zarathustra desires above all else, a sky emptied of the gods, is not visible again through the holes in ruined church roofs, but really thanks to these holes. The pure sky is an image of the world liberated from the teleological time of theistic providence, indeed even from the divine necessity that pantheism attributes to the world. Yet for all that it is god-less, the pure sky is acknowledged to be a gift of the same metaphysical-Christian history of God that it only seems to negate: the sky’s pure eye peers through holes in church roofs. Zarathustra, though an “old atheist,” can now love “even churches.” I call this Zarathustra’s affirmative atheism. I also link affirmative atheism to the conception of eternal recurrence as a self-abolishing anti-teaching. In the eternal return, Zarathustra’s atheism is finally indistinguishable from a history of churches and therefore negates itself. But although it is not a new teaching, affirmative atheism points to something novel. This is an atheism that can no longer be taught in doctrines but must be lived as fate.

Lead in Modern and Contemporary Art

Lead in Modern and Contemporary Art

Potential and Impact of Incorporating Roof Photovoltaic to Enhance Environmental Sustainability of Historic English Churches in the United Kingdom

The Church of England (CofE) is responding to climate change by taking measures to reduce their CO2 footprint under its flagship programme -‘Shrinking the Footprint’, to facilitate the CO2 emission reduction target of 80 % by 2050. Meeting this target will require both energy efficiency measures and zero carbon energy generation of which solar PV technology is a frontrunner as it has a substantially lower CO2 footprint than grid’s electricity, with no moving parts, low maintenance and a long service life. Conventional church roofs built along the East-West axis offer the ideal pitches and orientation for collecting solar energy. However, within the CofE’s vast estate of over 15,000 church buildings, 78 % of these buildings are listed and hence care must be taken to protect the building fabric. With this context in mind, this study identifies the benefits and concerns associated with the application of rooftop solar PV on historic English Churches and evaluates viable technologies currently available. The specific design and procedural requirements have been investigated and the process map of the implementation methodology established and illustrated through a case study of an existing church. Results showed that rooftop solar PV system has the potential to reduce the GHG emissions substantially, ranging between 75 %–84 % for electricity and between 20 %–27 % for gas based on the current demand and the choice of technology option. Findings on the issues, design options and life cycle environmental impacts are analysed with discussion and recommendation of future adaptation at a national level.

Unraveling the role of Myotis myotis in the ecology and transmission of rabies-related lyssaviruses (RRLVs)

Purpose: Insectivorous bats have been found to carry a variety of Rabies-Related Lyssaviruses (RRLVs) across Europe, among which European bat Lyssavirus 1 (EBLV-1) is the most widely distributed. Despite the majority of lethal infections are reported from serotine bats, serological data suggest that other species might have a role in the ecology of this pathogen. EBLV-1 has been associated with spillover events to humans, domestic and wildlife animals, causing a neurological disease clinically indistinguishable from classical rabies. Unraveling its ecology would then be crucial in predicting and mitigating associated risks for public health. Methods & Materials: During 2012-2018, we investigated the role of Myotis myotis in the maintenance and transmission of EBLV-1, through the longitudinal screening of roosts for neutralizing antibodies and viral shedding. Five neighboring maternal colonies were investigated in Northern Italy, whose connectivity was assessed using genetic and capture-recapture studies. Results: Antibodies neutralizing EBLV-1 were detected yearly, confirming that M. myotis are constantly exposed to the virus in the area and do survive the infection. In addition, longitudinal data revealed wide oscillations of antibodies during a single reproductive season, suggesting waning of antibodies and waves of infection. All colonies showed similar serological trends over consecutive years. Indeed, we found evidence for genetic panmixia at the nuclear and mitochondrial level and confirmed the movement of adult females between roosts. Conclusion: Altogether, our results support the role of M. myotis as natural host for an EBLV1-like RRLV. While this bat species usually inhabits underground sites in the Mediterranean areas, M. myotis is a strictly house dweller species in northern areas, with all colonies investigated in this study being located in church roofs. Based on both serological and virological findings, we suggest that the risk for human exposure to the virus is limited, with viral excretion restricted to short predictable windows of time. We predict that this study will be useful to secure public health while maintaining a positive relationship between humans and these large vesper bats, whose critical role in the control of pest insects is well recognized in the area.

ROOF RECONSTRUCTION FROM AIRBORNE LASER SCANNING DATA BASED ON IMAGE PROCESSING METHODS

The paper presents a new data-driven approach to generate CityGML building models from airborne laser scanning data. The approach is based on image processing methods applied to an interpolated height map and avoids shortcomings of established methods for plane detection like Hough transform or RANSAC algorithms on point clouds. The improvement originates in an interpolation algorithm that generates a height map from sparse point cloud data by preserving ridge lines and step edges of roofs. Roof planes then are detected by clustering the height map’s gradient angles, parameterizations of planes are estimated and used to filter out noise around ridge lines. On that basis, a raster representation of roof facets is generated. Then roof polygons are determined from region outlines, connected to a roof boundary graph, and simplified. Whereas the method is not limited to churches, the method’s performance is primarily tested for church roofs of the German city of Krefeld because of their complexity. To eliminate inaccuracies of spires, contours of towers are detected additionally, and spires are rendered as solids of revolution. In our experiments, the new data-driven method lead to significantly better building models than the previously applied model-driven approach.

ROOF RECONSTRUCTION FROM AIRBORNE LASER SCANNING DATA BASED ON IMAGE PROCESSING METHODS

Abstract. The paper presents a new data-driven approach to generate CityGML building models from airborne laser scanning data. The approach is based on image processing methods applied to an interpolated height map and avoids shortcomings of established methods for plane detection like Hough transform or RANSAC algorithms on point clouds. The improvement originates in an interpolation algorithm that generates a height map from sparse point cloud data by preserving ridge lines and step edges of roofs. Roof planes then are detected by clustering the height map’s gradient angles, parameterizations of planes are estimated and used to filter out noise around ridge lines. On that basis, a raster representation of roof facets is generated. Then roof polygons are determined from region outlines, connected to a roof boundary graph, and simplified. Whereas the method is not limited to churches, the method’s performance is primarily tested for church roofs of the German city of Krefeld because of their complexity. To eliminate inaccuracies of spires, contours of towers are detected additionally, and spires are rendered as solids of revolution. In our experiments, the new data-driven method lead to significantly better building models than the previously applied model-driven approach.

Diverse construction types and local timber sources characterize early medieval church roofs in southwestern Sweden

A vast number of early medieval roof structures are still preserved in Swedish churches, yet countrywide surveys and detailed dendrochronological investigations, in tandem with building archaeology, are largely lacking. Here, we present new findings from four parish churches (Forsby, Forshem, Gökhem and Marka) in Västergötland, southwestern Sweden. The roof constructions, made from local oak and pine trees, were dated to the period between AD 1131 and 1157, making these some of the oldest preserved roof structures in Sweden and Europe. With the development of new regional pine and oak tree-ring chronologies covering the 10th to 13th centuries, we open up the discussion about medieval timber technology, wood utilization and the potential for future tree-ring based paleo-environmental exploration.

THE WAGON ROOFS AT ST JAMES’S PRIORY, BRISTOL

In most regions of England in the medieval period there was a strong overlap between the carpentry traditions employed in churches and domestic buildings. While some forms of assembly may be the exclusive preserve of either the ecclesiastical or secular spheres, certain technologies are common to both. In the south-west of England, extending into the southern Marches and South Wales, however, the two are entirely different — wagon or cradle roofs are found only in churches, never in vernacular domestic structures, which normally adopt a variant of cruck construction. Little systematic analysis has been done on church roofs, mainly because they are difficult to access. The chronological range of wagon roofs in the South-West has normally been placed in the fifteenth and early sixteenth centuries. The firm dating of the two wagon roofs of St James’s Priory, Bristol, has pushed the conventional range back to the mid-fourteenth century, and other examples in the region may be considerably earlier. This paper uses the Bristol roofs to speculate about the origins of the wagon roof type and the reasons why it remained an exclusively ecclesiastical form.

Medieval church roof constructions in North Schleswig and Southwestern Jutland – examples of tradition and innovation

Only few of the Danish medieval parish churches can be dated. This paper presents an attempt of doing so by the help of dendrochronology of a number of church roofs of different types. Results show this is possible although only in cases where original roofs are preserved in a sufficient degree. The typology of church roof constructions has been revisited and so has the general dating of types and their origins.

Lead Theft-A Study of the “Uniqueness” of Lead from Church Roofs

In the United Kingdom, theft of lead is common, particularly from churches and other public buildings with lead roofs. To assess the potential to distinguish lead from different sources, 41 samples of lead from 24 church roofs in Northamptonshire, U.K, have been analyzed for relative abundance of trace elements and isotopes of lead using X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry, respectively. XRF revealed the overall presence of 12 trace elements with the four most abundant, calcium, phosphorus, silicon, and sulfur, showing a large weight percentage standard error of the mean of all samples suggesting variation in the weight percentage of these elements between different church roofs. Multiple samples from the same roofs, but different lead sheets, showed much lower weight percentage standard errors of the mean suggesting similar trace element concentrations. Lead isotope ratios were similar for all samples. Factors likely to affect the occurrence of these trace elements are discussed.

Precise tree-ring dating of building activities despite the absence of bark: A case-study on medieval church roofs in Damme, Belgium

A detailed dendrochronological survey was performed on the medieval roofs of the Church of Our Lady (CoOL) in Damme, Belgium. Seen its complex architectural history, special attention was paid to the identification of consecutive building phases, based on combined architectural historical research and tree-ring dating. In total 64 increment cores were taken throughout the roof structures of the CoOL. All roof timbers are made of European oak (Quercus robur/petraea), of which only few have surviving sapwood or bark. Tree-ring dating confirms the late 13th/early 14th century construction date of the roofs. For all chronologies that were composed, the highest correlation values are found with reference chronologies covering the catchment area of the river Meuse. From the dating results of the timbers of the CoOL it becomes clear that the same timber source was used for nearly a century. On several of the examined roof timbers, rafting joints were observed, demonstrating that the timbers were indeed tied together as a raft and floated down the river.By implementing sapwood estimates in a Bayesian chronological model (OxCal), tree-ring series with surviving sapwood from coeval roof structures were combined in order to narrow down the time range for the felling date. Based on the refined interpretation of the felling dates, several consecutive building phases can now be identified and dated, leading to a new interpretation of the architectural history of the CoOL. Intriguingly, a marked interruption in building activities is observed around 1300. Probably this is related to the instable political situation at that time, caused by the armed conflict that emerged between the Count of Flanders and the king of France. Since Damme served as the outport of the riotous city of Bruges, it was alternately seized by the French and Flemish, both consuming considerable amounts of timber and other building materials for military fortifications. Potentially this led to a shortage in building materials and provoked a stop in building activities.This paper demonstrates the power of Bayesian models to refine the interpretation of dendrochronological dates in architectural analyses of medieval historical buildings.

Time and Place: Medieval Carpentry in Staffordshire

Two- or three-bay houses with square panel and straight braces in the walls, and side-purlin roofs with tiebeams and single collars trusses, were common in much of the post-medieval Staffordshire. Although such buildings are the predominant visible expression of structural carpentry in the county they are markedly different from surviving medieval buildings. The most common type of medieval building in the area is crucks-framed; approximately sixty examples remain, mainly in rural areas. With the exception of crucks and church roofs, which are largely beyond the scope of this paper, most of the surviving medieval carpentry was commissioned by people of high social status. West Bromwich Manor House and Handsacre Hall were built for well-connected patrons who could afford to employ the best, highly mobile carpenters; their aisled and base-cruck open halls were a polite veneer laid over the indigenous vernacular building traditions. Collar-purlin roofs and other box-framed structures in the county are generally older than those post-and-truss building which can be dated. However, post-and-truss building with sparse framing and timbers of poor scantling would be less durable than other structures; the absence of early examples does not disprove their former existence. A small group of collar-purlin roofs in an around Burton-upon-Trent might have been built by carpenters who came from outside the area in response to the demand generated by the abbey and the newly founded borough.

Predicting soil lead migration: how can ancient church roofs help?

Soil Pb concentration data from the driplines of ancient Danish church roofs have provided a unique 800-year test of a contaminant transport model (SCEMR1) developed to predict the migration of heavy metals and radionuclides in soil. The model's performance in reproducing an 800-year accumulation of Pb in the soil around the church demonstrates the usefulness of simple transport models to assess the consequences of hazardous material, such as lead from industrial activities and even radionuclides from geological disposal of nuclear fuel waste, over hundreds of years. This study demonstrates that the model can be employed for detective work concerning human activities centuries ago and can also predict when a soil profile will reach its contaminant loading potential and pose a groundwater quality threat.