Maria Diodato

The Baptistry of Saint John in Florence: The Scientific Dating of the Timber Structure of the Dome

ABSTRACT The construction of the Baptistry of Saint John has a debated and uncertain history; the hypothesis on its main construction phases may span from the Roman period to the 13th century, according to different authors. This uncertainty is mainly due to the lack of primary sources and certain dating issues. By combining dendrochronological analysis and radiocarbon dating, some light was shed on the building’s history. Open at least from 897, in 1059 Pope Nicholas II re-consecrated the baptistry after several renovations. Around that period, the octagonal dome was probably built by using chestnut beams to tie the structure together. The dendrochronological analysis dated the silver fir element to 1268. This element possibly represents a replacement coincident with the period, between 1270 and 1300, when a substantial part of the mosaics of the dome was positioned.

Microwaves as a Remedial Treatment of Wood

A pilot experiment of microwave treatment was carried out on an Art Nouveau residential building erected at the beginning of the 20th century in Valencia, Spain. The timber structure was affected by a combined damage caused by Anobium punctatum (common furniture beetle or common house borer) and Kalotermes flavicollis (yellownecked dry-wood termite). After performing an exhaustive preliminary study on the building and analyzing the different alternatives of wood treatment, it was decided to use a microwave machine especially designed to eliminate this type of wood boring insects.This machine generates microwaves, a type of electromagnetic radiation, with a frequency of 2.45 GHz. This circumstance makes it possible to produce a high-frequency alternating electric field that causes the rotation of the molecular dipoles of water. Because of this continuous rotation the temperature of the water rises considerably.By heating up the humidity inside a living being, as in the case of xylophagous insects, an artificial fever in the body is generated, and since the animal is not capable of tolerating this temperature, it dies.In order to eliminate xylophagous insects, the wood moisture content (usually between 10% and 12%) and the presence of water in wood boring insects (around 90%) must be taken into account. Due to the greater content of humidity the increase of the temperature is higher and quicker in insects than wood.After having studied and experimented with different combination of power and time of exposition to the microwaves, this machine was found capable of eliminating any type of insect that may live inside the timber without harming the wood itself.Prior to this pilot intervention, several research works were carried out with the same microwave machine, both on structural timber and wooden works of art. In all these studies it was observed that no damage was caused either to the wood or to the finish of the works of art including pigments, polishes, stains etc. On the other hand, 100% efficacy was achieved in the elimination of xylophagous insects.This article describes the design, experimentation and perfecting process of this microwave machine and its pilot application on structural timber in an Art Nouveau residential building. As an example of method, the intervention followed the main steps of diagnosis and treatment testing including the analysis of several options of intensity and time that led to the positive final results obtained.

Understanding Spanish Timber Jack Arch Floors: Examples of Assessment and Conservation Issues

Jack arch floors are structures made of timber joists, with round or squared section, and segmental vaults either made of flat tiles or poured plaster conglomerate. They are especially diffused along the Mediterranean coast of Spain and can be considered as a main feature of the historical and vernacular architecture of the area. In order to assess and grade these structures several Spanish standards have been considered; however, even if the information contained is useful the Italian standard for the on-site diagnosis UNI 11119 of 2004 has been preferred. The method described in this standard leads the assessment through the grading of each and every timber element and the assignation of bearing properties that are essential for the consolidation project. This article will expose three examples of jack arch floors of the Valencian Community graded using the Italian standard and the conservation issues that arise from the results.

A Peculiar Spanish Timber Floor, the "Revoltón": A Diagnostic Example at the "Palacio del Marqués de Benicarló"

The paper deals with the application of the Italian method for assessing on-site and diagnosing timber elements to a distinctive Spanish type of horizontal structure called “revoltón” i.e. jack arch floor. As in Spain does not exist a specific regulation for the on-site diagnosis of timber elements, this analysis was performed according to the Italian standard UNI 11119. Due to the peculiar features of the jack arch floor some modifications were applied to the method.During spring 2012 the authors had the opportunity to carry out a pilot project by making a diagnostic analysis on a whole three stories building. The building, “Palacio del Marqués de Benicarló”, located in Spain in the town of Benicarló, between Barcelona and Valencia, was erected during the second half of the XVIII century. It maintains the original internal distribution and structure, and it is characterized by precious ceramic decorations on walls and floors. All the horizontal structures studied inside the palace were jack arch floor except the roof structure that was also made of timber.The results of the project described in the paper clarify the specific problems of the horizontal structures and the roof surveyed during the fieldwork. These results are accompanied by several plans that represent the information recovered on-site and lead to a complete assessment of the structures. The plans include the grading based on wood defects, the local moisture content of wood, the superficial and inner decay due to insects and rot and the deformation of the joists. In this way it was possible to locate the areas of the palace where more problems were concentrated, and better understand the causes and origin of the damages.

INTRODUCTION OF THE SUSTANAIBILITY’S CONCEPT IN THE ARCHITECT’S TRAINING. APPLICATION AND RESULTS

This article presents the results of the application of the Project for Educational Innovation and Improvement “ARQUITECTOS para el FUTURO. La sostenibilidad como factor de calidad en la arquitectura” [“ARCHITECTS for the FUTURE. Sustainability as a quality factor in architecture”] (PIME/UPV 2017-2018), through several degree and master’s subjects within the current training of architecture students at Universitat Politècnica de València (UPV). Although sustainable thought, design and construction are not innovative activities, as it has been shown to be so by such architects as nonagenarian Balkrishna Doshi, recent winner of the 2018 Pritzker Award, Alejandro Aravena (Pritzker 2016) or Diébédo Francis Kéré (Global Award for Sustainable Architecture 2009), among others, at the UPV School of Architecture a lack of understanding of the term has been observed, as has its subsequent misguided and fragmented application. In view of the above, this project was implemented to generate teaching/learning of new knowledge, skills and competences relating to the concept of ‘sustainability’. The execution of the project was based on the learning by doing methodology through three main practical tasks. The first was to identify and define the three fields environmental, socio-cultural and socio-economic on which sustainability is based. The second was to examine the sustainability of historically relevant architectural constructions and 21st-century works. Finally, learning and becoming skilled in the operation of the certification tool has shown the high cognitive level of students, their extensive cultural baggage, predisposition to teamwork and excellent skills in critical thinking. Results have exceeded the initial expectations for the project, which has produced the interest of our students in increasing their knowledge of design, composition, materials, building techniques and authors working in the field of architectural sustainability on the one hand, and on the other a fluidity in the analysis of architectural works and development of critical thinking on these in terms of sustainability.

The Timber Dating of Giotto’s Bell Tower in Florence (Italy)

ABSTRACT The Bell Tower of the Florence Cathedral is an outstanding example of Italian Gothic architecture and is one of the most famous buildings of Florence. This study aims at characterising the wooden structures of its roof by determining its tree species, dating the structural timber and, thereby, identifying the restoration phases and maintenance operations. Silver fir (Abies alba Mill.) was the only species found, which was floated downstream to Florence from the Casentino area in the Apennines along a network of rivers. Dendrochronological analysis showed that none of the roof timber specimens date back to the 14th century, when the Bell Tower was built. The present structure is therefore the result of repairs and replacements that continually occurred over the last 200 years. As a cause of frequent restoration our analysis indicates fast wood decay under the unfavorable environmental conditions of the attic, which can be attributed to the infiltration of moisture from the top of the roof.