Mills and industrial buildings

The structural use of iron in building construction occurred first in connection with industrial buildings.

The most important innovations in the structural use of iron in building construction, at least before 1840, took place in the development of textile mills. To trace this part of the story, it is necessary to return to the period in the late 18th century when cast, rather than wrought iron was the principal material in use.

Iron frames for industrial buildings were first introduced as a means of producing fireproof buildings.

The earliest skeleton frame industrial buildings had timber structures. Multi-storey buildings of timber post and beam construction within masonry walls were always vulnerable to fire, however, especially textile mills where cotton fibres were handled in an oily, often candle-lit atmosphere. By the 1790s the roll-call of disasters was such that the first steps were taken to substitute cast iron for timber, initially in columns but later in beams as well.

The earliest attempts to produce fireproof structures involved the use of brick jack arches and iron columns acting in conjunction with timber beams.

The first buildings in Britain with 'fireproof' structures were a cotton mill at Derby and a warehouse at Milford both put up in 1792-3 by William Strutt. In place of timber floor joists he substituted brick jack arches which sprang from skewbacks mounted on timber beams. The skewbacks were iron plated, and the undersides of the beams were plastered, while the spandrels above the arches were filled with sand. To complete his fire-resistant system, Strutt replaced the usual timber posts with cruciform iron columns.

The next step was to have an all-iron framework of cast iron beams and columns supporting a brick jack-arch floor.

The use of iron beams first occurred in the flaxmill built at Shrewsbury in 1796-97 for Marshall, Benyon and Bage and designed by the third partner Charles Bage. In this structure the beams are cast in two sections, bolted together in a cross-flange on the centre line of the building. In section they have a skewback base, designed like Strutt's timber beams to carry brick arches: their profile, concealed by the brickwork, rises at mid-span. At the outer walls the beams appear to rest on timber bearings within the brickwork (hardly ideal in a supposedly fireproof structure), whilst internally they are supported by a triple row of cast iron columns. The centre line of columns on the ground floor is adapted to take the drive shaft from the neighbouring engine house.

The system used by Bage in the 1790s was refined and developed over the next 30 years.

After the pioneering work of Strutt and Bage no subsequent episode in the development of framed mill construction was quite so dramatic, though cumulatively what happened in the next thirty years was just as significant. As Skempton has stressed, the design of Bage's beams was not a hit and miss affair but was based on mathematical formulae which he was willing to share with others. In a later mill built at Leeds for his old partner Benyon, Bage pared down his beam cross-section to an inverted T-section, with the bottom flange carrying the brick arch as before. Versions of that type of beam predominated until the development of the first I-section beams in the 1830s. Meanwhile his cruciform columns had been superseded by hollow cylindrical ones, which could serve the double purpose of carrying stem heating or the downflow of rainwater from the roof.

Although the early uses of iron framing were well published and the information on their construction and general arrangement was readily available, little architectural use was made of this new technology in the first half of the nineteenth century.

Broadly speaking, mills and other industrial buildings represented a world apart into which few professional architects ventured. Yet by the 1840s there was no lack of literature on the subject of iron for architects to refer to - publications by Hodgkinson and Thomas Tredgold (though Tredgold's advice on the design of beams was faulty), plus a growing spate of architectural journals. Anyone in doubt about frame construction could, for instance, gather the essence of what needed to be known from reports in the Builder and elsewhere of William Fairbairn's evidence on the collapse of Radcliffe's Mill atOldham in 1844.

Where iron framing was used in architecture its presence was rarely acknowledged.

Buildings of the scale of mills were not that common amongst projects entrusted to architects, and when iron was used, for instance by Robert Smirke at the British Museum c.1824 or by Charles Barry at the Reform Club 1837-41, the effect looked to the uninitiated like timber and plaster construction. On the two most noted occasions before 1850 when iron was given full play in the interiors of public buildings there was no hint from outside of the internal arrangement. J. B. Bunning's Coal Exchange in the City of London 1847-9 (demolished) concealed an iron frame, space galleried atrium, behind two palazzo office blocks, and Labrouste's Bibliotheque Sainte-Genevieve in Paris 1843-50 had a scholarly Renaissance stone facade to its ironwork barrel-vaulted interior. Even if these were, as Nikolaus Pevsner once claimed, "the earliest buildings whose aesthetic character is determined by iron", they kept their secrets well.

From the middle of the nineteenth century the iron framework began to find architectural expression and a few buildings were built that anticipated the modern architecture of the twentieth century.

Two notable British buildings were Gardeners Store, in Glasgow and the boatstore at Sheerness Dockyard. In Glasgow, Gardener's store was erected in Jamaica Street in 1855-56 on an iron frame system patented by a local ironfounder, Robert McConnel. This did not go so far as to have a jack arch construction within the frame like most mills - the floors were timber - but its two street facades were cast iron, their fenestration growing progressively richer on each storey. At the naval dockyard at Sheerness (1858 - 66), the boat store was begun two years later and, for the first time in a building of that size, made no dependence on load-bearing walls. Designed by G. T. Greene, and erected by the engineering contractor Henry Grissell, its cast and wrought iron beams, carried on H-section cast iron columns, form a complete structural frame, logically expressed in its four storey elevations. The most often-heard remark about the boat store is that it could have been built a hundred years later which, apart from being a compliment to Greene's prescience, raises the issue why such a structure had so little impact in its own time.