GWR Route: Banbury to Wolverhampton

Leamington Shed: gwrls3980

This view of Leamington locomotive shed shows the composite roof construction and glazing. The shed had two parallel ‘A’ frame truss roofs, which sloped at forty-five degrees. This angle was deemed necessary with glazed roofing and was typically employed where the span of each frame was between thirty and thirty-four feet. Larger spans were considered to be uneconomic, as they were difficult to clean / repair and resulted in large gable ends. The roof principles were carried between a centre row of five equally spaced cast iron columns and matching side wall brick piers. These piers were constructed at thirty foot intervals in the side walls. Between the piers was ordinary panel brickwork (one foot, one and a half inches thick). The wall piers were one foot, six inches thick and the height to the principal shoe was eighteen feet. The standard Great Western Railway principal was designed to be strong and simple and to resist corrosion. The centre girder was eighteen by seven inch and the principal rafters were of pitch pine, (nine by five inch). The tie bars were steel rods, enlarged to equal area at the thread. The union pieces were cast steel, and the heads and shoes cast iron. The tie rods were painted to provide additional corrosion resistance, and joints or corners avoided. The pitch was fifteen feet. The most suitable roof covering had been found to be one inch boards with Countess slates (twenty by ten inch) nailed to lateral timber battens. The central roof area of each roof originally had a raised clerestory with a glazed top and louvered sides. This remained until after nationalisation, but from the photographs it can be seen that this clerestory had been removed by 1961. The side louvres were dispensing with, the glazed area was enlarged and lowered to the same level as the main roof. This left about one third of the roof area glazed, with steel glazing bars spanning the gap. It is likely that one of the propriety two piece glazing bars that trapped the glass panels was used as these dispensed with the need for putty (this was considered unreliable on long steel glazing bars as the differential expansion between the bars and the glass caused dry putty to crack.

Above each road was a series of smoke troughs arranged in a continuous length. The smoke troughs were constructed entirely from wood (including the fastening) to resist attack by sulphurous gases. The boarding was three-quarter inch thick on a three by two inch framing. The smoke troughs were three feet wide at bottom and are suspended from the roof principals by four wrought iron straps. At the top were smoke chimneys, each one foot, six inch square inside and made from double boarding. When calculating the roof loadings, an additional fifty pounds per square foot of horizontal area was allowed for the smoke troughs.

Robert Ferris

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