Corrugated Iron Architecture
Herd Groyne Lighthouse (1881), South Shields, Tyne and Wear
(Photo: Emma Joice)
Loathe it or love it, corrugated iron
(CI) has woven its way into our cultural
landscape. Its unique qualities have
captured the imagination of engineers,
designers and ordinary people for almost
180 years, resulting in a diverse architectural
legacy that has touched the lives of millions
around the globe.
The significance of CI is now recognised
particularly in countries such as Australia and
Iceland where it is commonly found in both
historic and modern contexts. In contrast,
the UK has been comparatively slow to accept
the cultural value of CI, many observers
considering it subordinate to more permanent
and traditional materials. Considerable
numbers of historic CI structures still survive,
but many of these are under increasing threat
from neglect, development pressures and
changing social and economic conditions.
This article explores the development
of corrugated iron and considers
the problems and opportunities for
conserving existing historic structures
and adapting them for economically
viable and sustainable alternative uses.
HISTORY AND DEVELOPMENT
Henry Robinson Palmer, who recognised
its potential for covering wide span
roofs, patented corrugated iron in 1829.
The following year, Palmer, who was an
engineer and architect with the London
Dock Company, built a large shed at the
docks roofed entirely of self-supporting
corrugated iron sheets and spanning 40
feet. The use of CI quickly proliferated and
notable examples from this early period
include parts of Chatham Dockyard in
Kent and Liverpool Lime Street Station.
Eminent engineers including Isambard
Kingdom Brunel embraced its unique
characteristics in iconic structures such
as London’s Paddington Station.
The iron building revolution was
inexorable in its influence on architects,
engineers and progressive members of the
manufacturing community who saw the wider
potential and developed a type of construction
that is uniquely resonant in the collective
architectural consciousness: prefabricated
corrugated iron buildings.
By the 1840s the production of fully
prefabricated CI buildings was established
in Britain. Many of these buildings fed the requirements of colonial expansion into
countries such as Australia and South Africa.
The domestic market for prefabricated
buildings was also growing, and as transport
links improved, the pallet of locally available
materials was expanded to include sheet iron.
Public fascination with this new and exciting
material was such that in 1845 an ‘iron palace’
built in Liverpool for export to Africa was
displayed to the public, who paid a small fee
to view it.
However, the public love affair with
corrugated iron during the first half the
19th century does not appear to have been
unanimous or unconditional. Contemporary
reports suggest that some bishops were
unwilling to consecrate iron churches and that
the public would not tolerate it in their towns
SOCIAL AND ECONOMIC INFLUENCES
The latter half of the 19th century was
characterised by increasing industrialisation
and a steady migration from the country into the towns and cities. Many of
these urban settlers endured difficult
working and living conditions, and found
comfort in religion which played an
increasingly important part in people’s
lives during much of the 19th century.
|Regular painting is often all that is needed to ensure that iron cladding remains in good condition. Simple
features such as this decorative ridge piece require particular attention to ensure the character of the building
Companies such as William Cooper and
Boulton & Paul helped to feed the demand for
chapels, churches and Sunday schools along
with many other types of CI building, which
were sold in large numbers and transported
across the country. Many of these religious
buildings survive today as a visible reminder
of the prevalence of CI buildings during the
19th and early 20th centuries.
CI AS A REPLACEMENT MATERIAL
Rural landscapes changed forever during
the late 19th and early 20th centuries as
corrugated iron replaced materials that
had persisted in local building traditions
for centuries. Thatch in particular, which
had become associated with rural poverty,
was often replaced or sheeted over with corrugated iron. As a consequence, local
vernacular styles were partially eroded
but, paradoxically, CI also extended
the lives of many rural buildings.
Until the early 20th century most military
structures had been permanent. However,
the first world war acted as a catalyst to
the development of one of the once most
ubiquitous of CI buildings, the Nissen hut.
Named after their designer, Captain Peter
Nissen, these distinctive structures were
cheap to manufacture, easy to transport and
simple to erect, and they solved the huge
logistical problem of housing millions of
troops. Nissen huts continued in military
service through both world wars and beyond.
Following the first world war, attempts
were made to develop the Nissen hut design
for the residential housing market but this
proved to be uneconomical and only a handful
were ever built. Many Nissen huts survive
today and have been successfully adapted to
a wide variety of uses, a testament to their
versatility and robustness.
New building types proliferated in Britain
during and between the two world wars.
Many were associated with the newly formed
RAF, but one in particular was produced
on an enormous scale. At least 1½ million
Anderson shelters were distributed to British
households during the second world war to
help protect the population from German
bombing, making it possibly the most widely
produced prefabricated structure ever seen in
Britain and one that is deeply embedded in the
memories of a generation.
||The significance of a building is not always apparent from its appearance. Stripped of its corrugated iron
cladding, this early 20th-century structure forms part of a peat processing plant and is a rare survivor of an
industry dating back to medieval times. The structure is Grade II* listed and a scheduled ancient monument.
The idea that corrugated iron could have
any sort of cultural significance has
been slow to take hold in Britain. This
has been a particular problem for the
smaller prefabricated structures, many
of which have been demolished.
Nevertheless, the architectural and
historic significance of CI is now more
widely recognised and there is a greater
understanding of the less obvious attributes of
these structures such as innovation in design
and construction, associations with people
and places, positive contribution to urban and
rural landscapes, and economic value. Some
examples have been given statutory protection
and several have been carefully dismantled
and erected at open air museums.
Despite greater awareness and
understanding, however, the significance of
many CI buildings remains undervalued.
In some cases comparatively good
but isolated examples remain quietly
undiscovered, while other examples
may fail to become part of the historic
environment records due to difficulties in
making comparative value judgements.
The threats to historic CI structures are not
as obvious as those facing more mainstream
buildings. Climate change legislation may lead to the loss of CI buildings as unimaginative
owners, designers and planners fail to
appreciate how many of these buildings can
be successfully adapted to provide valuable,
efficient and comfortable spaces.
|Poor maintenance can lead to the loss of important visual elements.
Long-term vacancy and often minimal
security leaves many historic CI buildings
vulnerable to theft, vandalism and arson. The
relatively high fire loads of CI buildings and
the often secluded locations may mean that
any arson attack would very quickly lead to
total destruction of the building.
Many former religious buildings are
located in picturesque rural locations, and
although there is normally a presumption
in favour of retaining existing buildings, the
arguments for demolition and redevelopment
can be persuasive. The same buildings are
often sold subject to a number of restrictive
covenants which can severely restrict their
market appeal and lead to further problems
associated with long term vacancy.
The single biggest threat to corrugated
iron is undoubtedly neglect. Fluctuating
economic fortune, the abandonment of
buildings, and a failure to undertake even
the most basic maintenance all precipitate
the decline and, in some cases, loss of these
Historic CI sheets were produced in a variety
of lengths, widths, weights and profiles.
Typically sheet sizes are 3-10 feet long and 1830
inches wide although other sizes were made
to order. Profiles tend to conform to the ridge
and furrow or wave pattern with an average
pitch of 3-5 inches. Historically, CI sheets
were produced according to the Standard
Wire Gauge (SWG) system of measurement.
Sheets used for roofing were typically 18 SWG
(1.2mm) thick and weighed around 1.2kgs per
square foot. This compares with commonly
available modern sheets which weigh around
0.7kgs per square foot.
Most corrugated iron was galvanised
but sheets were occasionally supplied as
‘black iron’ (ungalvanised). The quality of the
metal varied along with the quality of the
materials and the proficiency of the workers
employed in the galvanising process. Along
with other factors, this variation in quality has
undoubtedly had an impact on the long term
survival of corrugated iron.
Prefabricated buildings of all
shapes and sizes were constructed using
simple lightweight timber and metal
frames to support the CI cladding.
While many agricultural and industrial
buildings merely required the corrugated
iron to form a weather-tight shell,
large numbers of CI buildings were
constructed with elaborate interiors.
Most of the chapels, pavilions, mission
rooms and other small prefabricated
buildings that survive are constructed using
a framework of 100 x 50mm (4 x 2 inch)
softwood timber. Floors are usually suspended
timber, with the entire building normally
sitting on a masonry plinth which was built
prior to the arrival of the building. Many of
these buildings have surprisingly comfortable,
sometimes even elaborate, interiors. Roof
structures vary enormously, from simple
scissor trusses to impressive arched-braced
||Corrosion of corrugated iron cladding is often the
result of changes in ground level.
Often thought of as an ephemeral material,
corrugated iron has in many cases far
exceeded its expected service life, but
condition is often a reflection of the
building’s use and the owner’s willingness to
undertake simple but regular maintenance.
Galvanising was perfected in this country
soon after CI was introduced and offered
a long-lasting and economical means of
preventing corrosion by applying a thin coat
of zinc to the metal sheets. Ultimately this
coating degrades or becomes damaged in
some way allowing the unprotected metal to
become exposed to the atmosphere, resulting
Corrosion often begins where two sheets
overlap, the small gap setting up a capillary
attraction which allows the joint to hold water.
This can lead to an electrochemical reaction
that causes the zinc coating to preferentially
corrode beneath the overlapping sheets. This
type of reaction can also occur in positions
where fixings made from a different type of
metal have been used. This process is likely
to be accelerated in marine locations and
areas subject to acid rain due to the increased
conductivity of the electrolyte solution
that connects the metals and allows the
electrochemical reaction to occur.
Rapid and extensive corrosion can also
be found where CI wall cladding has been
partially buried due to changes in ground
levels or alterations to the plinth. Most
corrugated iron will have been painted at
some point during its life, if this has been done
regularly the incidence of serious corrosion is
normally far lower.
Holes can sometimes be seen in the CI
cladding where sheets have been removed
or replaced and fixing bolts placed in
different locations. This can lead to water
ingress and accelerated corrosion around
the hole. Impact damage caused by vehicles
can often be seen on industrial or military
buildings, and it is common to see sheets
peeling away from their supporting structure
where fixings have been damaged.
Large CI buildings often have iron or steel
frames supporting the cladding. Metal ties,
rods and brackets are also common, and where
these components are concealed they are at
particular risk from undetected water ingress.
The majority of small prefabricated
buildings are constructed with softwood
frames and a large number of other timber
components. Simple maintenance is often
all that is required to ensure the timber
remains in good condition. Unfortunately,
neglect is common and timber decay is
often found in external joinery items such
as windows, doors, barge boards and fascia.
Unless there has been long term neglect
and water ingress, the timber frames and
floors are often in excellent condition.
REPAIR AND CONSERVATION
Regardless of the type or age of a structure, the
principles of conservation and maintenance
are largely the same. The process must start
with a clear understanding of the structure
gained through documentary research and
physical examination and recording. The
significance of the structure needs to be
identified at an early stage in order to assess
how any repairs, alterations or changes in
use will impact on the special qualities of the
building. Typically this will involve retaining
the visual characteristics and as much of
the historic building fabric as possible.
|This semi-derelict estate church manufactured by Boulton & Paul Ltd during the 19th century demonstrates how
some corrugated iron roofs imitated roof structures of a much grander status
Clearly it is important that any historic corrugated iron is repaired whenever possible.
There are several appropriate techniques.
Where there has been a total failure of
the paint system, this should be taken back
to sound metal. This can be achieved in situ
by using a combination of hand tools and
the application of a suitable chemical paint
stripper. If the CI sheets are to be removed
from the building a wet blast system may be
useful for removing large areas of paint. This
approach has the advantage of eliminating any
toxic dust where lead paints have been used.
Localised areas of damaged paint should be
rubbed back (using a wet abrasive for the same
reason) and repainted.
If the metal has started to corrode, areas
of light rusting can be removed with wire
brushes or abrasive papers and any remaining
rust treated with a rust converter. More
serious corrosion can be removed by carefully
controlled low pressure wet or dry blasting
or by the application of an acid gel, although
these techniques are best carried out in a
Where there has been extensive corrosion,
these areas can be repaired by welding in new
sections of CI, ideally cut from a sacrificial
sheet salvaged from the same building. This
approach requires that one or more sheets
will probably need to be replaced but ensures
that the material used in the repair is totally
compatible. When new sheets are required to
make up any shortfall these should be an exact
match in size, weight and profile, and the
type of fixings and method used to attach the
sheets should also match the original.
CI buildings require only basic measures
to ensure their long term survival, but as
many are left unoccupied for long periods it
is important to ensure that regular planned
maintenance is carried out.
Organic or other types of debris left lying
on a roof creates areas where moisture can
become trapped. Steeply pitched roofs tend
to be self-clearing, shallower pitches should
be inspected and cleared on a regular basis.
Similarly, gutters, downpipes and gullies
should also be checked to ensure they are
Many prefabricated buildings have large
voids or undercrofts beneath the floor and
it is important to check that air bricks or
other openings are kept clear to enable the
ventilation of these spaces.
Arguably the most important task is to
ensure that all the exterior paintwork is kept
in good order. Localised failures, especially
in external joinery, can allow water to
penetrate into the structural frame and lead
to corrosion of the corrugated iron inside
the wall cavity. Many modern paints now
have excellent anti-corrosion properties and
long renewal cycles. However, these need
to be considered carefully in light of any
important historic decorative schemes.
ADAPTING CI BUILDINGS FOR
||Part of a former historic iron works: notice the distinctive
pattern of corrosion to the roof covering, which
corresponds with the fixing points and sheet overlaps.
Increasing pressure to develop existing sites,
climate change legislation, and changing
economic and social trends mean more
CI buildings are threatened with demolition
or inappropriate alteration. With a little
imagination and the political will, many
of these buildings could provide viable
and sustainable spaces for a wide range of
alternative uses. Large numbers of CI aircraft
hangars are being used for storage, light
engineering, transport and leisure purposes.
The London Science Museum, for example,
has successfully used a former RAF hangar to
house its large object collection.
The exteriors of CI buildings are sensitive
to change and if they are to retain their special
qualities and visual identity all external
elements normally need to be retained.
Internal spaces are usually less sensitive to
change and provide a flexible space capable of
sub-division. Many smaller prefabricated CI
buildings offer opportunities for adaptation to
residential, business, leisure and community
uses. If done with sensitivity and imagination,
redundant mission rooms, chapels, hospitals
and other CI structures can be adapted to
provide energy-efficient, sustainable buildings
that respond to the increasing pressure to
Most small prefabricated buildings are
built on a simple modular timber framework
that provides a clear cavity between the inner
and outer cladding of around four inches.
Inserting rigid or other forms of insulation
into this cavity can be achieved with little or
no visual impact and can enable the thermal
performance of the building to comply with
current building codes.
Obtaining insurance and finance for
CI buildings adapted for residential and
other uses can be challenging but is possible
through a number of companies which
specialise in buildings of non-standard
construction. Typically, insurance premiums
will be higher and the number of risks covered
will be limited. Mortgage companies are also
likely to require detailed surveys and ask for
With improved understanding and a
greater awareness and interest in these
once ubiquitous buildings, the future looks
brighter for the relatively few remaining
examples. Buildings that until recently
were often considered eyesores and unfit
for purpose are now being rescued as
their contribution to our architectural
landscape is more widely appreciated.
J Davies, Galvanized Iron: Its Manufacture
and Uses, E & FN Spon, London, 1899
G Herbert, Pioneers of Prefabrication, Johns
Hopkins University Press, London, 1978
DS Mitchell, INFORM – Care and Maintenance of Corrugated
Iron, Historic Scotland,
A Mornement and S Holloway, Corrugated
Iron: Building on the Frontier, Francis
Lincoln, London, 2007
I Smith, Tin Tabernacles: Corrugated Iron
Mission Halls, Churches and Chapels
of Britain, Camrose Organisation,
B Walker, Technical
Advice Note 29 – Corrugated Iron and other
Ferrous Metal Cladding, Historic Scotland,