The Roofs of Abingdon, Oxfordshire, England

Keith Roberts, BSc, CEng, MICE, MIStructE MAE Roberts Consulting Abingdon, Oxfordshire, England

Roof Consultants Institute

Proceeedings of the RCI 21st International Convention Roberts ­ 125 ABSTRACT

The objective of this paper is to describe the different traditional roofs of an English town, from the lead roofs of St. Helens Church (from 1200) and County Hall (1678), to the thatched roof of the Barley Mow Inn (1350), to the clay tile roofs of Christs Hospital almshouses (1750), to the slate roofs of the Napoleonic gaol (1820) and the Morland Brewery (Speckled Hen, 1870), to the asbestos cement sheeted roofs of the MG car factory (1930).

In contrast, the roofs of several modern buildings constructed since 2000 will be presented, including the Sports Centre (aluminium standing seam and single ply membrane) and the Sophos software headquarters (glass and stainless steel).

The paper will examine some of the roof construction details that help to shape the character of an English market town.

SPEAKER KEITH ROBERTS is an independent chartered engineer specializing in roofing and cladding. Over the past fifteen years he has inspected and reported on the condition of more than 400 roofs of industrial, commercial, and public buildings throughout the UK and Ireland. He teaches and writes technical articles, including pieces published in Interface in January and February 1996. He is an active member of the CIB/ RILEM committee on roofing systems. .

Roberts ­ 126 Proceeedings of the RCI 21st International Convention The Roofs of Abingdon, Oxfordshire, England

This year marks the 450th anniversary of the Royal Charter given to Abingdon on Thames allowing it to trade as an English market town. This paper briefly describes some of the traditional roof forms to be found in the author's home town, which is located in central England, five miles south of the university city of Oxford and 50 miles west of London. HOUSING On arriving in the town of Abingdon, with a modern­day population of around 50,000, first impressions are likely to be of residential housing estates to the outskirts of the old town center. In England, the pre­ dominant external roofing material for housing is the interlocking concrete roof tile laid to a slope of between 25º and 35º. Older properties were covered with clay tiles or Photo 1: Aerial view of Abingdon Town Center looking natural slate, depending upon local avail­ towards St. Helens Church. ability and cost. ST. HELEN'S CHURCH Christians have been worshipping on the site of St. Helen's for over a thousand years. The present build­ ing was begun around 1100 and finished in 1538, although there have been numerous internal alterations over the years. St. Helen's has the distinction of being the second widest church in England, with five aisles, making it ten feet wider than it is long. This presents challenges for the roofers in constructing and maintaining four valley gutters. Indeed, the churchwarden's accounts from 1657 report that carpenters and slaters were busy in the church and on the roof. Many cartloads of slate were brought to the church yard, scaffolding went up, and some lead was renewed, which was just as well, as two payments for brushing snow off the roof and tower indicate a cold winter. Keeping the inside of the church dry remains of particular impor­

Table: Types of roof covering and construction dates for housing tance since in the Lady Chapel in England.

Proceeedings of the RCI 21st International Convention Roberts ­ 127 there is a medieval ceiling com­ pleted in 1391, which shows the lineage of Jesus, according to St. Matthew's gospel, painted on 52 oak panels and linked by a sym­ bolic vine. COUNTY HALL At one time, Abingdon was the county town of Berkshire and the principal council meetings were held in the old County Hall in Market Square. This three­story stone building was built in 1678 by Christopher Kempster (a mas­ ter mason who worked with Sir Christopher Wren on St. Paul's Cathedral), and used as a County Assize Court and market house. It has a fully­supported lead roof. A special lead casting notes that this was replaced in 1956 by the Photo 2: St. Helens Church, built between 1100 and 1538. roofing contractor Norman and Underwood, who thankfully are still trading. In England, there is a mer there is public access to the eral thousand buns were thrown long tradition of laying rolled lead roof, from where there are good by local councillors from the roof sheet on the roofs of civic build­ views across Abingdon and the of County Hall to the public gath­ ings, lead being a soft metal laid surrounding countryside – all this ered in the market square below. in sheets between 1.8 and 3.1 mm on a building designed and built thick. There is a set of good work­ more than a century before 19TH CENTURY BUILDINGS ing details published by the Lead Jefferson's Monticello in Virginia. Sheet Association. The first major development of A popular local tradition is the this century to the south of the One of the special features of custom of throwing buns from the town center and on the banks of the old County Hall is that on roof of County Hall to mark royal the River Thames was the gaol Saturday mornings in the sum­ and special occasions. The last built between 1805 and 1811 by event was in 2002 to celebrate the French prisoners of war. Pitched Queen's Golden Jubilee when sev­ roofs in natural slate covered the

Photo 3: Public access to the lead­covered roof of County Photo 4: Slate roofs of the Old Gaol built by French Hall, built in 1678. prisoners of war, 1805 ­ 1811.

Roberts ­ 128 Proceeedings of the RCI 21st International Convention gym, and curved, self­supported aluminium standing seam roofing to the swimming pool and tennis courts. These roof forms are the most common currently used in the UK for commercial buildings. Next door to the Sports Center there is the new headquarters of Sophos, an anti­virus software company. The building is notable for its extensive “brise soleil” solar shading to the front glazed wall of the building envelope. Finally, a few miles to the south of the town is the new Diamond Light project, to be com­ pleted in 2007. This is a 200m­ diameter torus­shaped building with a 33,000 m2 curved alumini­ um standing seam roof, which will

Photo 5: Flat roofs of the shopping center. house a very powerful synchro­ tron to be used for medical and materials research. massive building, which later was The retail area of Abingdon used for the storage of grain, and town center was redeveloped in CONCLUSION more recently, as a health and fit­ the 1960s with many flat roofs Abingdon today is an old mar­ ness center. covered with multi­layer bitumi­ ket town with a rich variety of roof nous felt. Nearby Morlands developed types and constructions, protect­ their brewery with the brew house ing properties where the building 21ST CENTURY BUILDINGS roof also clad with natural slate usage has evolved over the cen­ and recently converted for resi­ Within the last couple of turies. dential use. Morlands gained years, a new Sports Center has international fame with its been designed and built with PVC Related Web sites: single­ply membrane roofs to the Speckled Hen brew named after www.abingdon.gov.uk an MG sports car. 20TH CENTURY BUILDINGS To the west of the town, on what was once open fields, Kimber developed factories to build MG sports cars between 1929 and 1979. As with so many industrial buildings in the UK, the roofs were comprised of corrugat­ ed asbestos cement sheets bolted to steel purlins and supported on lightweight steel trusses. These original corrugated sheets have proven to be a reliable long­term form of roof cladding, although modern­day health and safety leg­ islation requires care when demolishing buildings with the presence of asbestos fibers. Photo 6: Barrel vault aluminium standing seam roof of the Sports Center, opened in 2002.

Proceeedings of the RCI 21st International Convention Roberts ­ 129 www.leadsheetassociation.org.uk www.diamond.ac.uk www.robertsconsulting.co.uk

Photo 7: Solar shading to the Sophos headquarters, opened in 2004.

Photo 8: Torus­shaped aluminium standing seam roof to new research facility. (Photo courtesy of Diamond Light Source Limited.)

Roberts ­ 130 Proceeedings of the RCI 21st International Convention