are many different natural stones and each has a different mode
of weathering depending upon its structure and chemical composition.
There are two principal agents of decay:
Deterioration of stone by frost action is caused by the expansion
of freezing water contained in bedding planes or pores. Frost damage
is mostly to horizontal surfaces, such as the upper sides of coping
stones and cornices where unprotected stone may be thoroughly soaked.
Deposits of soluble salts, in the form of a layer on the stone,
is the principal cause of decay. The formation of the layer is due
to atmospheric impurities, constituents of the stone itself or salts
introduced in other materials, such as mortar.
The constituents of the salts form a layer which differs in structure
from the bulk of the stone and, in the course of time, tends to
flake off and exposes a face for the elements to attack again.
Expertise is required to identify the state of defects in a building.
Ill-advised attempts to arrest the decay of stone often inflict
further damage and may accelerate the process of decay.
Restoration work takes many forms. This may involve stone sections
being rebuilt or indeed being removed and replaced. When new stone
is introduced it should be compatible with the old.
This task has always been difficult, especially where sandstone
has had to be replaced, due to problems in matching colour and texture
of the stonework to be repaired. Alternatives to natural stone require
experienced operatives under skilled supervision who have the patience
and determination to produce the effect specified.
Stone cleaning is often a part of
the refurbishment specification and in itself requires the skills
and knowledge of experts.
are a number of methods available and, as each project is individual,
our masonry surveyors will advise on the best process to use.
Most projects involve water cleaning using nebulous sprays or jetting,
although new technology, in the form of dry media stripping, is
available and used. The latter allows controlled cleaning/stripping
so that vulnerable surfaces are protected and not damaged.
In some circumstances, plain ashlar can be redressed to remove
the weathered face, exposing a new surface of reasonably sound stone
which can often postpone the need for a replacement.
Such experience demonstrates that there is no need to be deterred
by the common belief that stone deteriorates repidly if the weathered
face is removed.
The expertise of our masonry experts is recognised by many, including
the Historic Buildings and Monuments Commission and the Cheltenham
Borough Council whose policy to maintain the Regency features of
Cheltenham does much to enhance the intrinsic value of such a town.
The majority of contracts undertaken by us are on period properties,
however we also have a sound technical knowledge of cast stone -
a synthetic structured material intended to be used in a similar
manner as natural stone. Indeed cast stone is often made to represent
a particular natural stone and often the reproduction is so good
that the difference is imperceptible, except to the expert.
The skills and experience of our local craftsmen in stonework ensures
workmanship of the highest quality in all aspects of stone building
and stone walling.
Our surveyors, in conjunction with project managers, can advise
on products and materials, while on site we are able to complete
the specification with our specialist fixers.