In my previous blogs we have looked at lime mortar and the
benefits of using this. Rather than focusing in on a specific subject such as
lime, in this blog I thought I would discuss the facades of the early 20th
century. This is a very broad subject, every building may have been built using
slightly different techniques, however there are some generalisations which one
can make to discuss them for someone new to this subject.
Whether you are retaining a façade, which is increasingly
common today, or just trying to understand its construction or to understand
why some stone elements of the façade may have failed, the information below
should be useful starting place.
The Georgians and early Victorians built buildings using
traditional methods, using masonry walls using brick and stone and lime mortar.
Using these traditional methods they were still able to create some impressive
buildings, in these they used timber to span areas in the building and facades.
My next blog may address an interesting Georgian example of this.
However in the later part of the Victorian period the use of
steel frames started to develop, this transformed the height and scale of
building that could be built and this technology continued to develop into the
20th Century. The demand from clients and architects of the day were
to create masonry facades for these high rise buildings, in London you can see
clear examples of this where early 20th century buildings were built,
the design is typical of their age, making references back to the Georgian period
of the stone or brick façade.
As can be seen in the
drawing and photo of the assembly of the large cornice above, the steelwork
forms an integral part of the structure of the stonework. Today we would us
stainless steel or other non-ferrous metal which would not rust within the
structure. When these structures where erected ferrous steel was used which can
rust in the presence of moisture, resulting in the steel expanding with the
growth of the rust and the stone being unable to expand to accommodate this
movement, this results in the stone fracturing and failing. (Drawings taken
from ‘Modern Practical Masonry’ by Edmond George Warland, first published in
1929 by B.T Batsford, London, re-published in 2006 by Donhead PublishingLtd.)
Sometimes in the news or trade press we hear about the
failure of a section of stone from these early facades, many of which are now either listed or
non-designated heritage assets. A common reason for the failure of stone
facades is due to the use of iron fixings. As a Conservation Architect I
encounter the problems which the historic use of iron cramps and fixings used
within natural stone can cause huge amounts of damage. In the presence of moisture, when this iron
is imbedded within an inflexible stone facade, the expansion of the iron with
the growth of the rust puts pressure on the stone making it fail, because the
stone is unable to accommodate movement.
As can be seen in the
drawings above the iron frame and secondary supporting structure is integral to
the stability and fixing of the stonework, which from the street is hidden from
the casual observer. (Drawings taken from ‘Modern Practical Masonry’ by Edmond
George Warland, first published in 1929 by B.T Batsford, London, re-published
in 2006 by Donhead PublishingLtd.)
It is important to understand the common methods of the
construction of these stone facades in order to understand how it may have been
built. This becomes crucial when working on these buildings. Although for each
individual building and project a series of investigations are required to
confirm the exact type and extent of fixings which were used.
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