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ARCHITECT'S ACCOUNT

building study

At the press day held in July 1995 to mark English Heritage's acquisition of Danson House, I said that the building was 'eminently repairable'. In the years that have followed I am pleased, and not a little relieved, to say that these words have proved correct.

At that time the house was on the At Risk register and rated grade A; in other words, at immediate risk of further rapid deterioration or loss of fabric. It had no proper roof cover, and the whole interior was heavily infested with pigeons, dry rot, and wet rot. In addition, there was structural failure.

In common with many large houses of the 18th century, Danson House has trussed partitions at first-floor level which 'hang' the principal floor beams, allowing large uninterrupted spaces to the piano nobile, the main reception rooms. At first-floor levels, to the east and west sides, the external ends of the trussed partitions were found to have been supported off apparent king-post roof-trusses spanning across the bay opening. These also supported the roof structures to the canted bays. A brick relieving arch spanned over the truss to spread the load from the masonry wall over to the north and south main masonry walls.

When the bays were extended in height by one storey around the turn of the 19th century, the roof trusses were removed, leaving the trussed partitions and 'hung' floor beams unsupported. On the east side of the building - ie above the dining room - this had been overcome by installing an iron beam below the ceiling, forming an unsightly downstand.

This was corrected by, first of all, analysing the load paths through the building and creating a conceptual model of its construction. To allow the added beam to be removed, we extended the main floor beam to span to the external wall of the bay, while inserting a 25mm diameter hanger with turnbuckle, rising up to a new timber and double steel-plate flitch-beam spanning across the bay opening at roof level. This reinstated the original load lines, albeit at a floor higher, while adopting materials consistent with the original fabric and later Victorian interventions.

The repairs were implemented in two stages. In addition to dealing with the structural failure, the first comprised the removal of infestation and decay, the installation of a permanent roof covering in Westmorland slate, and conservation of the external stonework. It also included reinstatement of the interiors of the principal rooms, except for some of the final finishes. Amid all the chaos, there had proved to be a substantial amount of extant fabric, which was invaluable when making good the losses.

A second contract dealt with the completion of the principal interiors and restoration of the remaining rooms at bedroom and terrace (ground) levels. Both these contracts were let using GC/Works/1 and their combined total was approximately £4 million.

Above-ground archaeology, led by Richard Lea of English Heritage, played a major part in developing the scheme. This included detailed in situ examination of the superstructure, components and finishes;

paint analysis; and documentary research. The last of these brought to light some rather good watercolours of the principal rooms painted about 1805 by Sarah Johnson, daughter of the then-owner of Danson House. These revealed the appearance of the rooms before they were remodelled by Victorian owners and provided a good basis, together with physical evidence, for re-presenting them in their 18th-century form. The paint analysis also proved helpful, in that a comparison of paint media applied to joinery elements assisted an understanding of the date of installation. Any project of this kind should benefit from such an exercise.

Brian Anderson, partner-in-charge of the Danson House project ,

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