beverley minster
Continued frompage 43 of varying degrees of suitabilitywere used. Fortunately, during the course of the 1970s’ Appeal-funded works, fine-grained, pale golden-coloured stone again became available in blocks from quarries, which had been winning it and crushing it for road stone and other industrial uses. Quarrying for building stones has always been a fairly marginal activity, with big overheads and huge wastage due to the geological vagaries of shallow-bedded and heavily-vented sedimentary deposits. Mortars to bed the stones and point the joints have
also come on a long way in recent years–or,more accurately, have reverted more closely tomedieval practice. Formore than a century the building industry has had a protracted love affair with Portland cement. It is a brilliantmaterial for making structural concrete, but,we nowknow, can have disastrous effects on traditionalmasonry construction, be it stone or brickwork. The deleterious effects derive fromtoo greatmechanical strength, too great impermeability in relation to the parent materials and chemical degradation fromthe sulphates introduced. The benefits of lime-basedmortars, the only ones available to ourmedieval forebears, are nowmore fully appreciated. There is a steady increase in
understanding the use of limewithin the building industry, but the battle is far fromwon. Lime-based consolidation and conservation of the richly-carved West doorwayswas carried out by Cliveden ConservationWorkshop in 1993.
RECENT underpinning exercises associated with the masonry of the rather poor late medieval foundations has been carried out by Fondedile, a firm specialising in this type ofwork and with a track record including projects at Ely Cathedral, St Paul’s Cathedral, the Tower of London, the Palace of Westminster, the Woolwich Royal Arsenal and even Harrods. Distortion of the vaulting over the Nave –
especially in themiddle of the length where the thrusts are less restrained by the West Towers at one end and the Transepts at the other – has been going on, probably, since construction in the 14th century. By 2003 we decided that the time had come to intervene. Archaeology revealed that the deeply-projecting 14th-century buttresses were well founded on earlierwork at their inboard ends, but the extended 14th-century foundations under the toes of the buttresseswere of compressible, irregular chalk blocks, unbedded and unmortared. Fondedile’s experienced teamwas able to drill inclined holes into these foundations and consolidate them with a lime-based grout, lubricated with pulverised fuel ash, to fill all the voidswith a material which, when set, was no stronger than the chalk but strong enough to accept the loads involved. Subsequent monitoring suggests that themovement has been successfully arrested. While Fondedile was on site, the firm test-drilled
the footings of the Percy Chapel, a late 15th-century addition at the north-east corner of the Minster, which was showing all the symptoms of parting company fromthe 13th-century parent masonry. This revealed the foundations to be in made ground and at least one metre shallower than the adjoining ones.
50 Cornerstone, Vol 32, No 2 2011
Above, new artwork alongside the ancient in Beverley’s Retro-Choir and Prayer Area.
Right, Ian Stewart inspects
metalwork at the fine 18th-century gates which stand in the North Quire Aisle.
Below, the 17th-century tomb of theWarton family, in the Lady Chapel
The chapel is built into an internal angle and,
therefore, comprises two large windows and a virtually free-standing corner pier. The solution here was to skewpin the existing footings to solid bearing strata some 16 metres below by inclined, slender, bored piles. Subsequentmasonry repairs have revealed howpoorly built this extensionwas, with corner buttresses scarcely bonded into the walls they were supposed to support. While Quibellswas busy in the 1970s and early
1980s working round the exterior of the building, repointing and repairing, another local firm, Lightowlers ofHull,were cleaning all the interior and exterior stonework and repainting vaulting webs, ironwork inwindows and elsewhere throughout the building. John Lightowler became a Trustee of the
Minster in due course, and is now succeeded by his son Charles, maintaining that close association with theMinster Old Fund.
CRUSHINGIT FORROAD STONE’ IANSTEWART
GOLDEN STONEAGAIN BECAMEAVAILABLE FROMQUARRIES, WHICH HADBEEN
FINE-GRAINED, PALE ‘INTHE 1970S,
TECHNIQUES for cleaning stonework is another area that has become increasingly sophisticated in recent years.During the 1970s work we basically justwashed the building with copious volumes of clean water. Areas of heavy soiling and sooty crust were physically scraped first, and dirt was agitatedwith bristle brushes once softened by the water sprays. We tried to limit the volume of water used, but it was still prodigious. Disposal of water and soiling was a considerable problem, especially in the interior, where precious woodwork was also at risk. Too great a volume of water risked saturation of the stonework. Thiswould
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