The 'Bookend' Effect
This paper describes the progressive longitudinal distortion of certain Georgian and Victorian straight terraces (known as the ‘bookend’ effect) caused by cyclical expansion and contraction of their continuous façades. Four specific case-studies are given, covering the range of purpose-built and converted terraces at risk from the bookend effect. The results of 2 years’ continuous movement monitoring of a long terrace with electrolevels is given, revealing complex diurnal and seasonal movement, estimated to range from 1428mm. The operational difficulties of electrolevels and the
validation of their output is described. A poor prognosis for the future life of old terraces is ventured. Remedies and palliatives are suggested, without which such end-of-terrace properties will inevitably collapse, like failed bookends.
C. Richardson and A.G. Messenger
Author(s): Richardson, C;Messenger, A G
Keywords: masonry;movement;terraces;19th century;party wall;movement joints;case studies;temperature effects