Matthew Bronski and Jordan Dick
i Senior Principal, Simpson Gumpertz & Heger, Inc., Waltham, MA, USA. MBBronski@SGH.com
ii Associate Material Diagnostic Engineer, Ramboll UK, London, England, Jordan.Dick@Ramboll.co.uk
ABSTRACT
North America and the British Isles both have a rich architectural heritage of buildings with sandstone facades. Lewis Mumford famously termed 1865-95 “The Brown Decades,” but the widespread use of sandstone extended well beyond these decades, and well beyond “brownstone” (brown sandstone), to encompass a broader range of sandstones spanning several centuries. Preservation professionals often face two profound dilemmas: 1) Many historic sandstone quarries are now closed, thus obtaining stones from the original quarry for use in preservation is often not possible. 2) Some sandstones were notoriously non-durable in the climate in which the building was constructed, and have been failing badly for decades. How do we avoid repeating this durability problem, while respecting the original historic fabric, and while not creating new problems by introducing localized “harder” sandstone in contact with a “softer,” less durable weathered original stone? Both dilemmas evoke the same difficult question: “Where the original stone has proven non-durable, and is failing badly, how should localized replacement stone be selected to balance compatibility and historic appropriateness with improved durability?” The authors present a broadly applicable guideline of principles and approaches for preservation professionals to consider in selecting suitably durable sandstone for localized use in preservation projects where the original stone is no longer available, and the original stone is deteriorating.
KEYWORDS: Sandstone, brownstone, selection, specification.
136-Bronski.pdf
