Wall Tie Replacement
PermaFix is an expert in wall tie replacement. We work primarily along the exposed south coast of England, which is the area of the UK where cavity walls were first built in volume.
Thousands of the cavity walled houses, in Portsmouth for instance, were built between 1890 and 1930 with steel ties connecting the inner and outer walls.
As the steel ties age and deteriorate then corrosion may set in, comprimising ability of the tying system to hold the walls together.
Wall tie survey
An inspection of the cavity wall ties serving an existing building should establish...
The type of connector used – vertical twist, wire butterfly, double triangle, etc.
The density and embedment of the ties in relation to today’s standards
The condition of the steel in respect of the absence or presence of corrosion.
When do brick ties need replacing?
Table 2 of Building Research Establishment (BRE) Digest 401 classifies ties according to a visual grading of the condition of steel. Table 4 of the publication provides an objective recommended action on the basis of the classification. The BRE recommendations may range from suggesting a further inspection within 5-10 years to an immediate call to action for a wall tie replacement scheme. Reports that we offer to our customers state clearly the unbiased and objective recommendations of BRE.
Replacing cavity wall ties
Wall tie replacement techniques have been developed over 30 years for the reinstatement of cavity walls by inserting new wall ties without need to demolish and reconstruct. There are numerous remedial tie products on the market and the selection of the appropriate system for a building depends on a number of factors, which include:
The make-up and strength of the inner and outer walls – brick to brick, brick to aircrete block, brick to concrete, brick to timber, etc.
- The condition of the cavity – insulated or non-insulated
- The type of masonry – solid, deep frog or perforated brickwork
- The axial loads to be resisted
- The differential movement potential between the walls
- The need for fire resistance, for example communal areas in blocks of flats
- The exposure to spray from the sea or salted roads
In some areas of the UK installation of new ties is all that is needed as thin wire connectors can be left to simply rust away. However along the South coast where we operate from Brighton to Southampton the built-in ties are generally of the vertical twist variety. These ties have potential expand when corrosion takes place, causing serious structural cracking and weakening of the outer façade. In such instances no wall tie replacement scheme can be complete without undertaking the painful task of removing or isolating ties that have potential to cause further horizontal splitting.
Watch this Wall Tie Replacement video to see the installation process of one of the tie systems we offer. The video shows the use of a twistfix wall tie that is hammered into a pilot hole, gripping the walls on each side of the cavity. Other options include ties with expanding mechanisms and connectors that are fixed into the brickwork with masonry adhesives.