Cavity walls were constructed to offer protection
from the elements and to create better thermal
qualities. They consist of two separate walls
"tied" together using some form of "cavity
wall tie". Large numbers of walls with metal
wall ties were constructed in the building boom
of the 1930's. After the Second World War, cavity
walls became a standard form of construction for
dwellings and many other forms of buildings. Old
metal wall ties commonly came in the form of a
strip of metal with a sacrificial protective coating
of either black bitumen or zinc.
the early 1980's the problem of cavity wall tie
corrosion became evident, identifying that the
zinc/bitumen coated steel wall ties which had
been used in the construction of cavity walls
deteriorated much quicker than had been anticipated.
In 1981 the British Standard for the protection
of metal wall ties in construction was amended
and the zinc protective coating was tripled in
of cavity wall ties has been found to be a much
more serious and widespread problem to walls throughout
the UK than was first anticipated, particularly
in exposed areas or in walls of particular construction
and with specific mortar types.
Visual Symptoms of Cavity Wall Tie Corrosion:
and Stepped cracking to masonry/mortar pointing/external
high level masonry.
order to assess existing cavity wall ties Woodworm
Treatment Services use various types of specialist
equipment. High quality metal detectors are used
to locate the wall ties within the construction.
After location the condition of the wall ties
is assessed using fibre optic boroscopes.
After assessment of the cavity wall ties Woodworm
Treatment Services will put forward a specification
for remedial works if required.
an independent contractor, we can select the best
product for each particular situation and recommend
the best possible remedial action to be undertaken
as and when necessary.