Wall ties function is a critical component in modern masonry wall construction. They are designed to distribute and transfer loads (wind, seismic, impact and other) from the external skin or veneer to the internal walls or structural support system of the building and provide stability to the external masonry walls.
Wind loads on an external wall can be considerable, particularly in exposed locations and there are many examples of wall collapses resulting from corroded wall ties and high winds (*).
Inspection for wall tie function & corrosion is important in cavity brick buildings where galvanized metal ties have been used. Where problems are identified, the installation of Stainless Steel Remedial ties and other masonry repairs and strengthening can reduce the risks and consequences of wall tie failure.
REMEDIAL WALL TIE SYSTEMS
There are two main types of remedial wall tie systems;
i). Mechanical e.g. DryFix
ii). Chemical e.g. ResiTie
Helifix (division of Leviat Plc) is the major supplier of both types of remedial wall tie systems in Australia and in the World (*).
TECHNICAL AND TESTING
Mechanical remedial wall tie systems rely on a mechanical or threaded connection between the metal tie and the brick, where the tie is impact driven into a pre-drilled pilot hole with the aid of a rotary hammer drill.
There is extensive evidence and test results (*) to show that the performance and longevity of the mechanical connection in the brick is very much dependent upon;
a). the quality and hardness of the brick
b). the care and skill of the installer when drilling the pilot hole and driving-in the wall tie.
c). the level of future cyclic loads e.g. wind and other loads on the brickwork.
Chemical remedial wall tie systems still require installation and proof load testing by skilled and qualified operatives, but because of the chemical cross linking between the proprietary adhesive and brickwork, extensive evidence and tests (*) show that when correctly installed, the performance and longevity of the chemical e.g. ResiTie system is far superior to the mechanical wall tie equivalents under continuing cyclic loads.
HELITEC STRUCTURAL SERVICES
Helitec Structural Services Managing Director, Jerry Lahra previously established and operated Helifix (Australia) Pty Ltd and Helifix (New Zealand) Limited for over 20 years until selling both businesses to international conglomerate CRH Group subsidiary Leviat, in 2012. During its initial 20 year period of operations in Australia, Helifix oversaw the independent testing of many of its products including Seismic tests carried out by numerous Universities and testing and research organizations and particularly in response to and following the major earthquake events in Newcastle, NSW and Christchurch NZ (*).
• Further information available on request.
For further information or to discuss your own building problem or project, contact Helitec on Telephone 1300 234 450 or visit our web home for articles on brick ties