Summary of Building Canopy and structural supports to former petrol filling station, constructed in 1960-61 to designs by architect Hugh Segar (Sam) Scorer and structural engineer Dr Hajnal-Kónyi. Reasons for Designation The canopy to the former petrol filling station, constructed in 1960-61 to designs by architect Hugh Segar (Sam) Scorer and structural engineer Dr Hajnal-Kónyi, is listed at Grade II for the following principal reasons: * Technical innovation: it is a particularly direct example of a hyperbolic paraboloid roof, an unusual and dramatic roof solution which was then being experimented with by a number of architects and engineers all over the world. * Architectural interest: it is a dramatic piece of concrete design which displays the hyperbolic paraboloid form in a daring manner. * Architectural authorship: the team of Scorer and Hajnal-Kónyi was advanced in the design of hyperbolic paraboloids. Scorer is chiefly remembered today for his three buildings that are substantially roofed in hyperbolic paraboloid shells, two of which are listed, one at Grade II*. * Architectural distinction: during a period when standardisation of petrol stations was introduced as an aid to product recognition, the example at Markham Moor is unique by virtue of its technical innovation and individual design. * Rarity: it is one of few extant hyperbolic paraboloid shell structures from the 1950s and 1960s. * Intactness: The canopy and four structural supports remain intact and uncompromised by the inserted building beneath. History The canopy, once part of a former petrol filling station, was built in 1960-1 by Hugh Segar (Sam) Scorer, of Denis Clarke Hall, Scorer and Bright, for Messrs. A. H. Turner Ltd. The total cost was £4,500. The canopy takes the form of a hyperbolic paraboloid shell roof, also known as a saddle roof because of its distinctive shape. An article in Concrete and Constructional Engineering (February 1962) shows the simplicity of the original structure. Thin shell concrete roofs were invented in Germany around the 1920s, as a means of achieving large spans with limited materials and at low cost. The strength of the roof lies in its shape, and the way it carries the loads by the forces exerted in the planes of the shell, rather than by the weight of their materials. The first shell roofs were simple barrel vaults. The earliest known to survive is Wythenshawe Bus Garage, Manchester, built 1939-42 (Grade II*), and it was only in the post-war years that experiments in the form were taken further. One of the first engineers to specialise in concrete shell techniques in Britain was the German refugee Dr K Hajnal-Kónyi, who arrived in London in 1936, and who went on to work extensively with Sam Scorer. Scorer became fascinated by the possibilities of shell roofs as a student, and designed a hyperboloic paraboloid roof as early as 1956 on a water tower in Ilkeston, Derbyshire. Meanwhile, in Mexico, Felix Candela was famously experimenting with ‘anticlastic’ or shells with double curvatures of opposing convexity and concavity, from which the hyperbolic paraboloid emerged as his favoured shape. The form was particularly appropriate for developing countries because of its simple materials and low cost. The ‘hypar', as it is sometimes known, enjoyed a brief fashion, seen in buildings such as the Commonwealth Institute of 1960-2 (Grade II*) and two other buildings by Scorer in Lincoln: the former Lincolnshire Motor Company Showrooms of 1958-9 (Grade II) and the Church of St John of 1962-3 (Grade II*). The distinctive appearance of the canopy at Markham Moor gave it landmark status during the 1960s and 70s. In the late 1980s it ceased to be used as a garage, and a roadside restaurant was built beneath the canopy. Details MATERIALS: Pre-cast concrete. PLAN: Rhomboid, 60 ft square on plan. EXTERIOR: The canopy is a hyperbolic paraboloid shell structure. It has sharp fins that point skywards while the sides sweep low towards the ground. Its form can be likened to a handkerchief, with two corners rising to apexes of 37 feet 4 inches above the ground, while the two opposite corners are only 5 feet above ground. At the dip in the centre, the height is 18 ft 6 in. The canopy is supported on its lower edges by four, simple concrete stanchions. A single-storey restaurant building in brick was built beneath the canopy in the 1980s. This has plain elevations with deep fascias, lit by large areas of glazing on the principal façades. The restaurant building does not have special interest and is excluded from the listing. INTERIOR: The interior of the restaurant building has standard late C20 fittings, typical of those found at motorway service stations, and is not of special interest. This list entry was subject to a Minor Amendment on 28/03/2012