Previously considered to be an inferior material to stone, brick
construction was rarely used in Britain until the close of the Middle Ages.
Gerard Lynch looks at its historical development over the last 600 years and
its conservation and repair.
Tudor brickwork 1485 - 1603
The popularity of the material can be traced to the revival of
brick-making in eastern England in the late 13th and early 14th centuries.
This was a direct result of lack of local stone, an increasing shortage of
good timber, and the influence of Europe where brickwork was used
extensively. By the Tudor period the brick-makers and bricklayers had
emerged as separate craftsmen well able to rival the masons. From
unsophisticated early work, brick building entered its heyday, rivalling
stone in its popularity as a structural material.
Bricks were generally made on site in wood, heather or turf fired clamps
by itinerant workers. Not only were standard bricks produced but also many
in extravagant and elaborate shapes, epitomised by those that formed the
spiral twisted chimney stacks for which the period is renown. The Tudors
further patterned their brickwork by inserting headers of over burnt or
vitrified bricks into the walling. These dark surfaces ranging from deep
purple to slate in colour, were laid carefully in quarter brick offsets in
mainly English bond or English cross-bond, to form a diaper or chequered
pattern within the predominantly red brickwork. Tudor bricks were irregular
in size and shape and therefore thick (15 - 25mm) mortar joints were
necessary to even these out. The slow setting mortar was of matured
non-hydraulic lime (often containing particles of the fuel used in its
production), and coarse sand in a ratio varying from 1:2 - 1:5, the joints
being finished flush from the laying trowel.
With the building of Hampton Court Palace, we have not only the seal of
royal approval, but a monument to the achievement of brick in this period.
The Geogian period 1714-1830
The late 17th and early 18th centuries were a high point in the use of
brick. Their manufacture was much improved, with blended clay, better
moulding and more even firing which lead to greater consistency in shape and
size. The colours of bricks changed in popularity from red, purple or grey
bricks fashionable in the late 17th century until 1730, when brownish or
pinkish grey stocks replaced the hot colours. These were followed in the mid
18th century by grey stocks, and, by 1800, the production of yellow marl or
malm London stocks, which were closer to the stone colour desired for a
Brickwork was generally of a very high standard, in mainly Flemish bond
although header bond was also popular in the early 18th century. Pointing
was executed to a similar standard. As well as giving more protection to the
weaker bedding mortar, fine detailing also helped to minimise the visual
impact of the joints so that the classical details could be displayed more
clearly. 'Tuck' pointing was the ultimate development in this quest. A more
expensive solution was to use 'gauged' brickwork popularised by Wren using a
facade of fine, colour-matched bricks cut and rubbed to exact units, and
laid in thin lime putty joints. However after 1730 this was considered too
expensive and was reserved for window arches, aprons and other ornamentation
Victorian brickwork 1830-1914
This was a period of revivalism in domestic architecture and industrial
building. The former seeking a return to 'medievalism' and other exotic
building forms as a relief from the unspirituality of the Machine Age. The
latter, for the infrastructure of factories, warehouses, railway bridges and
so on, all largely met through the cheap use of bricks. During this period,
a greater number of bricks were made and laid than during all the previous
periods. Brick manufacturing methods had improved in all respects including
quality accuracy, regularity and in range of colours available. From the mid
18th century onwards the manufacturing process, like many others, was
becoming mechanised. This enabled deeper clays to be used for pressing into
dense bricks for use on civil engineering works.
With improvements in travel and communications, bricks could be
transported over wide areas which removed the traditional local variations.
Improvements in the production of mortar also occurred during the late 18th
century through the use of washed and graded aggregates, often with
colouring. Also, the development of natural cements including Roman cement
and other hydraulic limes, which set quicker and stronger, were vital to the
speed of construction that the Industrial Age demanded. Portland Cement
appeared in the mid 19th century. Joints reduced to 0.3 inches (8mm) due to
the accuracy of the machine pressed bricks and continued to be finished in
various profiles. These were popular from the 17th century although the new
'weather-struck' and 'cut' style of joint became particularly popular. A
variety of face bonds were now used although, in the main, Flemish bond
predominated domestically, whilst English bond was favoured industrially. In
all matters of brickwork, the Victorian desire for enrichment was readily
achieved by the use of often garish polychromatic work, and the lavishing of
ornamentation by detailing mass produced purpose moulded 'specials' or by
Decay, conservation and repair
Before considering the most appropriate method of repairing brickwork,
correct diagnosis of the cause of failure is vital. Manufacturing defects in
bricks can be the result of under firing or impurities in the clay used.
These bricks decay more rapidly than better burnt bricks, especially with
frost action. They can also act as a point of entry for moisture, which in
turn will affect the whole wall, leaving it open to damage from frost and
chemical action. Free standing walls, parapets and retaining walls are
particularly vulnerable, and some judicious replacement may be necessary.
Poor Detailing can also contribute to failure through construction
defects such as: Decayed bond timbers, joists, timber lintels, plates or
bearers which have been embedded or built in to the masonry. The expansion
of rust on corroding iron and steel structural members, wall ties or
reinforcement embedded in the brickwork. Failure of arches and lintels from
inadequate bearings, or abutments. Poor bonding and inadequate or even
non-existent tying-in of brickwork. This can be due to a habit in the 18th
and 19th centuries of 'snapping' headers leading to a wall of two skins,
instead of one mass.
Alternatively failure can occur at the junctions between walls,
particularly where front and rear walls are insufficiently tied to the cross
walls. 'Corbelling' (over projecting brickwork) and oversailing are
especially prone to being insufficiently tailed-in to the main walling. They
are also susceptible to water penetration due to inadequate, or non-existent
protective weathering. Sulphate attack occurs when water is present with
cement based mortars, producing slow steady expansion of sulphate crystals
within the mortar or the bricks as the water evaporates. It can result in
damage and even failure of the masonry. This is particularly common in
unlined chimney stacks, where sulphates have been introduced by the burning
of sulphur-rich fossil fuels. Where chimneys have been designed without
bends, allowing rain straight down the flue, damp may appear on the chimney
breast with a possible resultant salt problem. This can especially occur
when the air is humid, or where the fireplace has been sealed without proper
ventilation. Poorly designed parapet copings without damp proof courses,
inadequate overhangs, and poor jointing techniques, which encourage damp
Remedial work to historic brickwork must be carefully selected after
expert analysis and should always be kept to an absolute minimum.
Consolidants should only be applied to decaying brickwork as a last resort.
Although predictably effective on soft porous bricks their use is still in
its infancy, and the long term affects of new techniques is less certain.
The consolidated brick face may behave in a different manner from the base
through thermal movement, resulting in eventual separation. Sealants may
induce similar problems. By sealing the surface they may inhibit or reduce
surface evaporation leading to a build up of moisture. This can result in
concentrating evaporation in other areas where crystallisation and frost
damage may be exacerbated.
Sealants should only be used in localised areas to prevent problems such
as the staining which occurs from water run-off from limestone dressings,
where it may be used after removal of the deposits.
The introduction of hard mortars is one of the most common causes of
failure in historic brickwork, leading to a failure of the mortar and of the
brickwork itself. Inappropriate cleaning methods may cause substantial
damage by removing not only the dirt but also the fireskin, leaving a pitted
face. Rotary carborundum heads again, destroy the surface as well as dishing
and scouring the 'arrises'. Such methods may actually accelerate re-soiling
and rate of decay by producing a more textured surface.
Vegetation although often attractive, is generally harmful to older
brick walls of traditional construction. Many types of ivy can cause serious
damage to brickwork particularly if it is in poor repair, or constructed of
soft, possibly spalling, bricks bedded in soft lime mortar where the
pointing is defective. If not carefully removed, ivy should at the least, be
heavily controlled and never allowed to reach eaves level where it might
block gutters and downpipes. In a strong wind, vegetation can also transfer
additional wind-load, pulling out guttering, parapets, and even a
Pigeons can also present problems, especially in city centres. Not only
can they force up loose roof coverings, but they will block up gutters and
downpipes with feathers, detritus and excrement, causing water penetration
and consequent decay. The faeces rapidly deface the external (as well as
internal) fabric, and may damage porous brickwork. Removal is difficult and
expensive. Control is therefore imperative, and can involve bird nets,
repellent gels, poisons, traps and even shooting.