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Hoop rust puts spires at risk

HUNDREDS OF Victorian church spires could be harbouring potentially dangerous design faults making them vulnerable to serious structural cracking, it emerged this week.

Several unsafe masonry spires containing rusting reinforcement have already been demolished or repaired around the UK. Church architects are now calling for inspection rules to be tightened to ensure earlier detection of the problems.

Debate centres on the current guidelines, drawn up in 1980 by the Council for the Care of Churches, which stipulate that all UK churches must be inspected every five years. But they only recommend visual examination from the ground or using existing access ladders.

Brian Anderson, a partner with leading church architect Purcell, Miller, Tritton said that as most spires have no permanent access, examination through binoculars was the only practical way to do the work.

But this does not reveal any cracking until it becomes quite large, he said, adding: This is a hidden problem which ticks away until it becomes serious and very expensive.

And with inspections usually funded locally by parish councils, architects claim funds only allow them half a day on site. Guidance should be more specific, they argue, and should include a rolling programme of more detailed structural examination.

Alarm was raised after the latest casualty was revealed a weakened 46m high spire on a 150 year old church in Birkenhead. Discovery of dangerous horizontal cracking earlier this month triggered an emergency evacuation of over 50 people living beneath (NCE 5 March).

Peter Moffat, a consultant with William Jones & Partners, said the 2mm wide cracks, running half way round the spire, will be examined in the next few days when access scaffolding is complete.

Temporary stitching has ensured the spire is now safe, he said. But we know of the dangers of rusting ironwork and this could well be a contributory factor.

The problem centres on horizontal rings of 25mm square wrought iron bars built into masonry spires at roughly 2m intervals vertically. This lead-sheathed hoop reinforcement, laid in chases cut into the stonework just above mortar bed jointing, was designed to strengthen tall spires against wind loading.

Danger point for the spire is reached after water penetrates the lead covering, allowing the wrought iron to rust and expand. Spalling occurs in adjacent masonry blocks, largely unseen within the mortar jointing until circumferential surface cracking appears, sometimes running right round the spire.

David Hayward

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