Wall Tie Testing and Spacing
Testing
Testing may be included as a routine part of the process of specifying and installing Helifix remedial wall ties.
During installation, a random number of ties may be tested at different levels and elevations to determine the pull-out load from both the near and far leaves. Pre-specifiction testing may also be included as a part of the survey of the building, with the identified pull out loads used to determine the density of ties to be fitted.
Load requirements
Load requirements will typically vary from one site to the next. However, as a general guide, it should be noted that wall ties are load sharing devices and that specifictions demanding high point loads are to be avoided as these can lead to sudden failure.
Typically, a tensile proof load of around 1kN at normal tie densities (see alongside) will be sufficient to satisfy SAA Masonry Code guidelines. With low strength materials, reduced pull-out values may be compensated for by inreasing the tie density.
Test unit
Pull-out tests on Helifix ties can be easily and accurately conducted on site using the Helifix Load Test Unit. The unit has been specifically designed with a collet-key which may be used by itself or with the Load Tester.
After the tie has been inserted into the material to be tested, the key may be placed over the tie end ready for testing. A load may be applied either manually as a fail-safe check, or in a controlled fashion through the Load Test Unit to give a direct reading.
Tie spacing
The SAA Masonry Code generally recommends wall ties to be spaced at not more than 600mm centres (vertical and horizontal) on unbroken brickfaces and not more than 300mm centres around openings. Geography, building type and wind exposure classification can all influence spacing requirements and the final specification should be confirmed by an engineer.
