Albion offer a variety of Sigma purlin systems to suit differing applications.

The Sigma purlin shape provides an efficient, robust profile that suits both short and long span conditions.

In most cases of popular building type sag rods are not required (subject to wind uplift conditions), see table on page 9 of Albion's Sigma Purlin Brochure.

Sleeves are required to provide continuity to the purlin section across the supporting rafters.

 
The most popular system, double spanning, has been specifically developed to minimise the number of sleeves, thus reducing the number of components and resulting in savings in installation time and component cost.

The sleeve details have also been considered in terms of simplicity and duplication.  All sleeves are the same length with identical longitudinal dimensions, uniformity reducing the chance of errors.
 

► Single Span Butt System

The simplest of the Purlin Systems. Use where design conditions dictate that no connecting Sleeves can be used, i.e. Purlin within depth of Rafter.