Tin Tabernacles
by Lizzie Induni, October 2002
Corrugated iron (CI) churches were designed and made in kit form, to be bought from catalogues. They were timber framed buildings externally clad with galvanised and corrugated iron, and lined with high quality tongue and groove boarding. Many had high levels of detail decoration. Outside, timber decoration was often richly carved. Interiors were often delicately enriched with stencilling. These were excellent buildings which proved very durable.
Survival
Tin churches may meet few of the rules of 'great architecture' , but they tell us as directly as any others about the aspirations, fashions and economic privations of common people. Most have a rich association of local memories. People will talk for hours on their fond recollections of dance night at the parish hall or the Jubilee tea.
History of Corrugated Iron
By the end of the 18th century iron sheet was being made on a large scale in Britain. It was made by pushing iron bars through rolling mills, rather like a washing mangle. The distance between the two rollers could be adjusted to make a varying thickness of sheet. Until the 1880s individual works had their own gauges and the main centre of production was the Black Country, round Birmingham.
The Industrial Revolution brought an increasing demand for large industrial buildings, and traditional roofing materials, such as tiles and slates were not suitable for large span roofs. This was because of the excessive weight load and the need for shallow pitched roofs. The first roofs were covered with sheet iron but it was soon found that if you corrugated the sheets their strength was vastly increased and their weight reduced. Skilful design of the corrugations allowed the lapping of many sheets to form a watertight roof. Whole sheets could be curved at right angles to the corrugations to make rigid arches. Huge spans of say 100 feet could be covered by 2 or 3 arches of Corrugated Iron, resting on tie rods.
Initially the focus of corrugated iron was as a roofing material but it soon became evident that it could be used for walls and doors. The idea for a light weight, prefabricated, portable building was born.
Prefabrication itself was not new. The timber framed buildings
of the medieval period were often constructed off site as a series
of flat trusses, these only being fastened together with side
framing on site. The frames were not transported long distances,
as they were too heavy, transport was expensive and materials
could be obtained locally.
Corrugated iron was ideally suited to prefabrication. It was light,
strong, compact and able to be cut into workable sized sheets.
Increases in population, empire building and mass emigration in the 19th century created a need for buildings which could be made in Britain and transported abroad in a 'flat-pack'. Corrugated Iron buildings fulfilled this need.
Galvanising
Galvanising is the process of electrically coating the surface of the iron with a layer of zinc. This layer dramatically increases the resistance of the iron to corrosion, transforming it into a long lasting material. Despite the popular description of CI buildings as 'tin', as far as is known, only zinc was ever used as a surface coating. True tin plate was reserved mainly for the canning of food.
The Spirit of the age
The Victorian Age was the 'age of
iron'. Developments in manufacture meant that iron could be made
cheaply and accurately on a mass scale for the first time in history.
It was in 1851 that building of the Crystal palace, a vast structure
of iron and glass, epitomised this new iron age.
Not everyone admired the use of iron in architecture. Many architects opposed it, including John Ruskin in his book 'Seven lamps of Architecture'. Should the traditional methods and materials of architecture be supplanted by new materials ? Corrugated iron was a revolutionary new material and the limits and rules of building technology had to be revised for it to win acceptance. Many architects shied away from this and never accepted the new material as anything other than low status and temporary.
Churches
If some architects flatly refused to accept corrugated iron,
others did not. Nor were civil engineers slow to see the possibilities
for the new material.
The very rapid growth in urban population during the Victorian
era caused a new wave of church and chapel building. The advocacy
of traditional materials by the Ecclesiological Society and an
architects such as Pugin, Street and Scott was irrelevant to the
church needs of the poor or those at the margins of society. It
was especially irrelevant to those settling at the frontiers of
new lands in America or in the new British empire.
In response to overwhelming pressures to produce cheap, rapidly erectable buildings that could be sited far from developed sources of traditional materials, it is no surprise that CI buildings started to be manufactured by engineers and builders.
Richard Walker, who had a works in Bermondsey, was instrumental in developing the technology of CI building manufacture. Charles Young of Edinburgh produced buildings that were in the catalogue for the Great Exhibition, where some of them were erected for display.
They were made available for sale through catalogues. Each building style: cottage, railway station , church or house was illustrated with a drawing, and a price. Size could be altered according to need.
Prefabricated iron churches were relatively cheap to buy, costing anything from £150 for a 150 sittings chapel to £500 for a 350 sittings chapel. Conventional building materials for the same would many times more.
By 1875 hundreds of CI churches were being erected, many with extensive gothic style embellishments.
Anatomy
Foundations are made from brick, which support the suspended floor timbers and wall joists. There is often a natural slate damp proof course between the brick foundations and timber frame.
Frame As with timber framed buildings the frame is erected in bays. The roof trusses line up with the vertical posts in the wall panels.
Cladding CI sheets are fixed with nails on the
exterior of the frame. The sheets overlap so that the rainwater
runs off the building (not into it) . Outside corners are constructed
so that the CI wraps around the corner. The interior is usually
finely finished in pine tongue and groove and often decorated
in elaborate stencilling.
Problems
CI buildings are easy to mend because of their simple construction.
Cladding The inherent weakness of CI sheeting is that of corrosion, particularly around the nails holding the sheets to the frame. Once it has begun it is irreversible. This corrosion will not immediately cause a weakening of the building but it will allow the ingress of water causing damp and potential decay of the timber framing and roof. The sheets are easily taken off by removing the nails on the outside of the building. Replacement sheeting can still be obtained, taking care to check the profile and size of the corrugations. It might be necessary to cut the sheeting to fit round the edges of windows and doors.
Painting When painting over galvanised sheet you must allow time for the galvanised coating to wear down about six months, or the paint will peel off. The new sheets must be primed with metal primer which will deaden the galvanised coat, then undercoated and gloss finished.
Roof Treat the cladding in the same way as the walls.
Windows These are unlikely to be structural, but will fit within the timber framework of the building. If a window frame is rotten in parts it may be worth removing the frame and repairing the damaged pieces, retaining the healthy parts of the frame. Repaint with primer, undercoat and gloss to match the other frames.
Guttering All rainwater goods need to be maintained in good condition as water ingress is the main threat to the building. Faulty down-pipes should be replaced with replicas and drainage from the site working effectively.
Interiors Most corrugated iron Buildings have pine tongue and groove boarding inside. If the board is rotten, broken or damaged , it can be easily removed and replaced. If the original is painted, match it with a suitable primer, undercoat and top coat.
Stencilling If you are fortunate to have stencilling in the form of lettering or decoration, then treat it sympathetically. Do not be tempted to paint over it and obliterate it. These delicate and beautiful decoration are often the highlight of the buildings.
Repair or replace?
With traditional old buildings it is more acceptable to repair than to replace. i.e. original 18th century windows should have their timbers repaired or not be entirely replaced on new wood.
The cladding on CI churches have a different problem. Although the cladding is a key component and therefore of historic value it is not really practical to consider conserving large areas of damage. The overall design of CI churches relies on the small decorative details : window design, roof vents, doorways and bargeboards, and from a decorative point of view, the corrugated iron is secondary. CI churches are at their visually most pleasing when the cladding is clean, freshly painted and efficiently attached to the building.
The small decorative details are vital to the overall design. It is essential that these are repaired and replaced like for like. The building only needs to loose 2 or 3 of these decorative elements and it quickly starts to look like a garden shed.
Use it or Lose it
When a building looses it's use, it rapidly falls into disrepair. But CI buildings are more versatile and adaptable than others. The timber framework and removable cladding is easily convertible. Externally, the building can be extended by adding extra framework and cladding. Internally, because the divisions are often lightweight studwork, it is easy to add or take away partitions.
Because they are versatile, many of these buildings have had a change of use without any apparent damage to their structure. A church can become a village hall, a dance hall or a Masonic Lodge without any alteration being made to the exterior.
Movability
It is often a debatable issue to move a building from it's original location and rebuild it in a place which bears no relationship to the vernacular style or local materials. No such problems occur with CI. They were designed to move. A derelict CI church can be dismantled and re erected 50 miles away and begin a new life as a shop. Provided none of the key elements of it's integrity are missing (i.e. windows, barge boards and roof vents etc.) no harm has been done.
Awareness and Protection
In this country, numbers of CI churches have dwindled rapidly. People perceive them as cheap and temporary regardless of their age. When they are not maintained they decay rapidly and are pulled down, not because they are falling apart, but because of people's perception of them as 'old, temporary and not proper'.
Very few CI churches have achieved the status of being listed. English Heritage will only list of a building is 'complete' i.e. with original furnishings, thereby giving little hope to building of changed use. Conservation areas offer very little protection. They are an intrinsic part of our cultural heritage and must not be passed over as if they were of no consequence.
CI churches must not be forgotten.
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