LECTURE

THE PRESERVATION OF HISTORIC BUILDINGS

Joint Lecture with the Institute of Structural Engineers by Ian Hume, on 3 November 1998

Ian Hume was formerly Chief Engineer of the Conservation Engineering Team with English Heritage and is now a consultant.

After being introduced by David Wardle, Chairman of the Institute of Structural Engineers South-Western Branch, the speaker opened by reminding the audience that listing a building does not freeze it in time, but controls the changes permitted, including change of use.
He first quoted Nicholas Hawksmoor in the 18th century and the Society for the Preservation of Ancient Buildings in the 19th to emphasise that the aim with historic buildings should be ‘Preservation in place of Restoration’ and to ‘stave off decay by daily care’.
His talk was illustrated by numerous slides showing ancient monuments and historic buildings from Grimes Graves, the pre-historic flint mines in Norfolk, to WW I aircraft hangers at Duxford and multi-storey flats in Bethnal Green, finishing appropriately with the Mausoleum at Castle Howard built by Hawksmoor.
The principles on which English Heritage work are:
1 Conserve as found
2 Minimum intervention
3 Like-for-like repairs
4 Repairs should be reversible.
These cannot all always be adhered to but should form the basis of decisions. In some cases either the state of the structure or financial restrictions make it necessary to approve the demolition of a building.
The questions asked during the discussion led to the speaker suggesting that the biggest innovation in structural engineering since building started was the construction of spans larger than the length of one tree.
A study of the effect of heavy road traffic on old buildings by the Road Research Laboratory and English Heritage indicated that the vibration may crack plaster and is unpleasant for the occupants but does not hasten the destruction of the building - old buildings are ‘flexible’ and settle rather than snapping as modern ones do.
A structural inspection every 100 or 150 years may be adequate if the owner ‘staves off decay by daily care’.
Don Lovell