L. Mulvin

Architectural detailing, weathering and stone decay

Abstract Examination of the effects of weather on the exterior of an historic facade is shown to be a necessary part of a conservation study by the information yielded from Regent House, Trinity College, Dublin. An investigation, by visual observation and recording of weathering and decay patterns, into the contribution made by the architectural features of classical detailing establishes certain points of interest. Eighteenth-century facade construction employed classical detailing for both decorative and utilitarian, protective functions, such as water flow control. As a result, water penetration within the core fabric of the construction was minimized, and mo, the degradation of the materials upon which strength and structural integrity depends was lessened. The study of patterns of weathering and deterioration is used to help identify areas in which the classical detail has failed or been improperly made or maintained. Such areas are associated with further repercussions on the stone and on iron fixings embedded in the constructions and indicate areas in need of repair attention. In this regard, a knowledge and understanding of the construction of the building becomes an essential factor in a conservation study of this nature.

BUILDING STONE CONSERVATION IN PRACTICE

Summary Serious deterioration in the fabric of historic buildings throughout Europe has necessitated extensive conservation and remedial measures. The conclusions of this study, together with that on the six EC buildings recorded in the Third EC Environmental R+D 1981-85 Programme, suggest that the quality of granite from certain quarries in the Dublin/Wicklow area is variable and that 18th century stone was mainly boulder stone, and stone removed from the upper quarry layers. It has been recorded that this stone, although of inferior quality, was used because it was softer and therefore easier to carve. Cleaning, treating, consolidating and repairing granite of this quality has its difficulties. It does not respond well to consolidation techniques, and attempts at manufacturing repair mortars are not fully satisfactory. No really successful alternative to stone replacement has been discovered.

ARCHITECTURAL DETAIL, WEATHERING, AND STONE DECAY

From an historical study, the precise constructional details are being established for Regent House, Trinity College Dublin, an eighteenth century building faced with granite and Portland limestone. The present state of the decay of the pediment can be partially understood as a cumulative effect of the loss of the essential protective details. The likely patterns of the flow of water over and percolating through the construction can be related to the mapping of decay typologies identified in an epidermicalogical survey of the building.The study points to need to reinstate and extend traditional understanding of architectural details as limiters of the flow of water over and through the stone work of a building thereby arresting increasing vulnerability to progressively more aggressive conditions.