Restoration of the fort du Randouillet barrack’s roofs, Briançon
Presentation
The Fort du Randouillet is located on a steep and narrow rocky mound, distinguished by its vast size spread over a slope of100 metres. The various buildings that make up this site were constructed to meet the requirements of military architecture of the time, and to adapt to the constraints of the site.
This results in a complex layout on three levels, similar to that of a medieval castle with its keep and inner bailey.
The barracks
Each of the three barracks is a rectangular volume measuring 54 mx 14.50 mand 9 mhigh, with a slate roof with a 45 degree pitch. Evidence shows that most of the original roof covering was of locally-sourced slate which was therefore perfectly adapted to withstanding local climatic conditions. This slate was comparable to “lauze” (local roofing stone) because it was of a similar size and laid in the same way. However, in the late 19th and early 20th centuries, the local slates were replaced by slates fromAngers, which were not thick enough to withstand the weather conditions, and therefore caused the roofs to deteriorate rapidly.
The appearance of the roof was changed by the different size and thickness of the slates and the way they were laid.
The rescue project
Work was urgently required as roofs had fallen in, chimney stacks were threatening to collapse and water infiltration posed a real danger to the immediate preservation of the buildings. Therefore, to render the buildings water-tight, the decision was taken to level the chimney stacks and cover the framework with corrugated iron sheets. This simple and cost-efficient solution is viable in the long-term, without comprising any future solutions and ensures that the buildings are made water tight immediately.
As the building methods for the roof structure have been properly documented, restoring it to its original state remains a possibility in the future.
Evaluation
Slate-coloured iron was chosen for its ease of application.
Leveling off the chimney stacks reduces the cost of restoration and in addition means that expensive and complex chimney flashing work is no longer required.
The general outline of the barracks will be retained as the overall relations of mass remain the same.