JIM CROFT
Newcastle Castle Keep repairs
With careful advance planning and execution of work on site an important 800 year-old building and visitor attraction receives a successful facelift.
The repair and consolidation work under way on the     of loose stone), re-pointing and, where necessary,
external walls of the historic Castle Keep in Newcastle     replacement of some of the 800 year-old sandstone
upon Tyne has involved a painstaking process of     blocks which form the outer walls and architectural
de-shaling (the physical removal of the outer skin     features.
An arched hood moulding above the window set also required attention. Here the severely weathered stone is being cut away and replaced with new profles. The restoration of weathered stone involves cutting back to sound material then introducing new face profles, rather than complete block removal and replacement. New stones are fxed with the help of stainless steel dowels. Bed thickness and line are honoured wherever possible and natural hydraulic lime mortars are used to maintain the integrity of the construction.
CONTEXT 106 : SEPTEMBER 2008
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A particular challenge facing the restoration team is the replacement of severely eroded stone detailing around a two-light window feature to the Keepís north elevation. The stone capitals surmounting columnar jambs have decayed so badly that there is no indication left of the original moulding detail which the masons could use for visual reference.
At the top of the north-east tower, almost 30m above ground level, the exposure has been so severe that several stone blocks which bridge over corbels supporting the tower battlements required complete replacement. A temporary supporting structure of props and needles was erected to carry the loading of the masonry above. The four badly eroded bridge-stones were carefully removed in sequence so that the masonry above remained supported by the corbels at all times.
Jim Croft is associate
director of heritage for
specialist conservation
contractor St Astier.
The 12th century Castle Keep stands on a steep-sided promontory overlooking the River Tyne. on the eastern elevations, which are open to the salt-laden winds blowing from the North Sea, surface decay of the stone blocks was found to be particularly severe, with 10Ė15mm thickness of loose, shaley material over large areas.
In 2006, the Keepís east elevation and fore-building received attention. In the current phase, the walls to the north and west elevations are being repaired.
Where necessary, new stone blocks are be used to replace originals which have deteriorated beyond repair. Replacement stone blocks have been sourced from a local quarry which offered a near identical material Ė a coarse-grained Northumbrian carboniferous sandstone with predominantly buff colouring and characteristic iron-staining.
The Castle Keep, open to public visit for 361 days a year, will remain open throughout the works.
one of the main challenges facing the conservation team before any work could start was access to the castle walls. The main east coast rail line runs at the foot of the north/west elevation and a complex web of scaffolding over-hanging the line had to be installed.
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CONTEXT 106 : SEPTEMBER 2008