Apex Ties

The M16 all-thread apex tie provides a functional and cost-effective solution, offering adjustment during installation where tolerance or alignment flexibility is required. Threaded bar apex ties are commonly used as tension members linking opposing purlins across the ridge.

The anti-sag bar apex option offers a quick-to-install and robust alternative where roof pitches and loading conditions are moderate. Anti-sag systems primarily provide lateral restraint and help prevent purlin twisting during erection and under uplift forces, making them suitable for many standard roof configurations.

Where higher loads, steeper roof pitches, deeper section sizes, or unrestrained cladding systems are present, a double-bracket strut brace may be specified to provide increased stiffness and load transfer at the apex. This arrangement typically utilises a more substantial 45 mm × 45 mm × 2 mm intermediate angle with matching support brackets, delivering enhanced torsional restraint compared with lighter tie systems.

In mono-pitch structures, forces are not balanced by an opposing roof slope as they are at a traditional apex. In these situations, a negative-facing eaves strut or equivalent structural restraint may be required to provide additional stability and reduce rotational forces acting downslope. Apex tie selection should be coordinated with the overall anti-sag system — for example:

Strut-type apex ties should be used in conjunction with strut or rigid brace arrangements where higher structural restraint is necessary.

These principles apply across both Z and Sigma section structural systems, ensuring consistent support performance and efficient installation.