Wall Tie Failure
What is Wall Tie Failure?
Wall tie failure can be a consequence of a construction defect. For example:
- where the original 'built-in' ties have been incorrectly fitted (perhaps allowing water transfer);
- an insufficient number of wall ties may have been installed, or at an inconsistent density;
- the wall is fitted with ties that are too short (perhaps not having sufficient embedment into one or both leafs); or
- the wall ties are omitted in part or omitted in full.
Wall tie failure can also be a result of a buildings natural aging and deterioration process. Over time the building's mortar beds undergo a chemical change through carbonation and the mortar becomes aggressive to the mild steel wall ties and their protective coatings. The life expectancy of poorly coated ties can be as little as 26 – 46 years. The design life of the building is typically much longer than this period and it therefore follows that at some point the wall may need replacement of its wall ties if the stability and the load sharing capacity of the wall structure are to be maintained.