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Salisbury Cathedral spire
Salisbury, Wiltshire, UK
Salisbury Cathedral spire
associated engineer
Not known
date  circa 1285 - 1333
era  Medieval  |  category  Cathedral  |  reference  SU142295
ICE reference number  HEW 508
photo  Jane Joyce
Salisbury Cathedral was built between 1220 and 1258, to replace the Norman cathedral at Old Sarum. The foundation stone was laid by Bishop Roger Poore. The spire that would make Salisbury the tallest church building in Britain was constructed a little later.
Originally the cathedral had a lantern, 35m above the floor, over the crossing of nave and transepts. At the end of the 13th century, work began above this level on the 33.2m high, 12.5m square tower, which is surmounted by the 54.9m high octagonal spire. This made a total height of 123.1m. The new structure added a further 7,000 tonnes to the 100,000 tonnes of the existing cathedral.
The spire is clad in 200mm thick Portland stone slabs, and the original Medieval wooden scaffolding can still be seen inside. The top 15m of the spire was constructed from the outside.
The nave and transepts crossing has four main columns, each 1.8m square and made from Purbeck marble. They are founded at a depth of just 1.2m with little footing spread. Each column exerts considerable stress approximately 164 tonnes per square metre on the gravel subsoil, resulting in appreciable settlement.
There are relieving squinch arches in the top of the tower, providing continuous seating in the spire. However, the tower walls began to move outward at the top because of the estimated 300 tonnes of horizontal thrust from these squinchs. In 1660, architect Christopher Wren added diagonal ties across the tower, and more ties were added at intervals down the years.
Between 1945 and 1950, the top 9.1m of the spire were rebuilt, and the iron cross was taken down from the pinnacle for display inside the cathedral. Consulting engineers Gifford & Partners then carried out substantial remedial works, including new stainless steel circumferential ties and a new reinforced concrete ring beam.
In 1991, a major repair programme started, partly funded by English Heritage. Under this contract the spire and tower were repaired and conserved. The work was completed in 2000. The spire now leans 700mm to the south and 400mm to the west.
The public can pay to take a tour of the tower up to the base of the spire, ascending 332 steps up a spiral staircase to 68m above the ground.
Supervising engineers (1950-69): Gifford & Partners
Research: ECPK
bibliography
www.salisburycathedral.org.uk
reference sources   CEH South
Location

Salisbury Cathedral spire