Visit to St Michael's, Bishop Stortford

St Michael's is a medieval church with Victorian extension of the tower, chancel and South aisle.

With the exception of the nave roof and tower spire all other roofs are covered in copper sheet, laid using the traditional method of standing seams and cross welts joining together separate sheets.

The copper has taken on a full green patina and shows few defects. The sheets are generally held very tight to the boards with little movement in the centre of the sheet. There is some noticeable staining of the copper due to run-of from steel fixings and pipes, in particular a expansion pipe to the heating systems discharges from height above the copper.

Victoria County History

In order to widen the search of potential case studies and to find earlier references to copper roofing in buildings I conducted a search of Victoria County History on-line. A number of volumes have been digitised and are available through the website www.british-history.ac.uk . I carried out a word search through each of the volumes for 'copper'. The results include references to manufacture, mining and small items of copper. In total 55 built reference were found. Considering the extent of buildings covered by Victoria County History searched this can be considered a small sample. The majority of reference were to religious buildings, which reflects the bias towards these building in the History.

The earliest reference was to a house in North Bradley in Whiltshire built around the 17th century, later demolished about 1800. The description stated 'All that is known of it is that it was remarkable for the number and size of its windows and that it was roofed with copper.

The chart below shows that date, were discernible, of the construction of the buildings or the re-roofing in copper. Even with the small number of samples there is a noticable increase around the 1880's and in the 1950's and 60's.

Visit to St Michael's, Swaton

St Michael's is a medieval church near Boston in Lincolnshire.

The nave, aisle and tower roof were covered by lead sheet. At the time of my visit the church had undertaken to replace the copper covering with new lead sheet. The copper sheet had been removed prior to my visit, however this gave good opportunity to examine the state of the timber roof below. The tall aisle walls allow the nave roof to continue uninterrupted over the aisles.

The copper roof had been laid in a traditional method with standing seams. Problems had started with cracks forming along the edges of the sheet along the seams. This lead to a number of water leaks. Repairs had been attempted by the application of adhesive tapes and mastic. Eventual failure of these repairs and with additional cracks forming meant that continuing with this form of repair was unsustainable. In addition some areas of the roof covering were starting to lift. This may be due to uplift from the prevailing wind passing over the ridge and parapets. A number of the copper fixing nails had been found to have failed.

Having decided that the copper covering needed to be replaced lead sheet was specified for the new covering. This was supported by English Heritage as the church had been covered by lead sheet prior to the copper being laid in 1957.

The architect for the church is Peter McFarlane who guided me around the works. The contractor for the repair works and lead sheet roofing is W. Howlett & Sons.

Visit to Chichester Cathedral

Visited 28th October 2009

The Cathedral Church commands a prominent site at the heart of Chichester. The steeply roofed nave and chancel are key elements of most views of the cathedral. Chicester Cathderal is the closest to the coast of any English cathedral.

The timber roof structure is highly significant and dates back to the thirteenth century. The roofs of the cathedral were covered in lead sheet up to the 1940's when is was decided to recover the building in copper sheet. One reason suggested for this approach was the high salvage value of the removed lead.

The method used to cover the roofs was a variation of the traditional method with the use of triangular rolls at the seams. Nearly all the copper is covered with a green patina except for a small area to the North East tower sheltered from the wind. For many years wind lift of the copper sheets has left to defects in the covering. The cathedral works has sought to fix down lifted sheets with by screw fixing them down just above the welt with a proprietary copper cup to improve the fixing qualities. Many of these fixings have subsequently failed.

No decision has been made on the when the covering will be replaced though discussions have started. Some small areas where water leaks were of concern have been recovered in lead. The defects in the copper covering are progressive and may be a consequence of the fixing method used, normally reserved for flat roof coverings.

I was invited and guided around the roof of Chichester Cathedral by the Clerk of Works, Ralph Tyrman.

Visit to St Mary's, Edlesborough

Visited on 27th October 2009

St. Mary's is a medieval church in the Vale of Aylesbury. The church is maintained by the Churches Conservation Trust and is opened to the public.

The nave, aisle, porches and tower are roofed in copper. The covering was replaced in 2002 following defects in the previous covering leading to water leaks. The copper was replaced using a long strip system with standing seems. The copper was laid over sheet boarding raised over the original roof boarding with ventilation gaps at eaves and ridge.

The church is raised on a mound at the edge of the village. It is in an exposed position. During period of high wind speed the new copper sheet can be heard drumming.

The copper has readily oxidised and turned a dark brown patina. Small areas of green patina have started to form.

The architect for the repair works is Philip Hughes. I was guided around the building by Gabriela Misuriello of the Churches Conservation Trust.

Following progress in my research

I am almost halfway through the research on my dissertation. I thought it might be helpful to keep a blog of the progress of my study. It gives me a chance to put down in writing some of the things I have found and some of the thoughts that I have. In the end they may find their way into the final dissertation.

The topic of the study is a little specialised, but that is the nature of the course that I am studying: Conservation of the Historic Environment at the College of Estate Management. The title of the dissertation is 'The Care and Maintenance of Historic Copper Roofing'.

Why choose this subject. Well, it is a material that I have specified from time to time in my work and like many people (though not all) I like the green colour of patinated copper and the way it brightens up the roofscape of many towns and cities. I did some initial investigation of the use of the material last year and found that little had been written on the history of its use or how it should be maintained. There also seemed to be some contradiction in conservation practice of copper roofing - common to many roof coverings - of a willingness to scrap the whole covering as soon as problems arise, a decision often aided by the particular characteristics of copper. This lack of general interest and seemingly unfashionability in its conservation peeked my interest and set me on the path of the study.