Flat Roof
On low pitched roofs, a built-up form of construction or a standing seam metal sheeting system is often employed. The following information concerns built-up roof construction in which a metal decking is fixed securely to the purlin by means of self drill tap fixings.

Tests have proven that when using Ward Topdek panels with Multibeam Purlins no additional restraints are required to those detailed in the table on page XX. The combined construction offers the restraint necessary to enable the published safe load tables to be used.

The load tables on page XX may be used for selection of the purlin. However, deflection requirements are generally given greater attention on low pitched roofs. The designer may use the general bending formula



in conjunction with the published section properties or the Kingspan Toolkit Software to evaluate a satisfactory deflection limit.

For this application the term ‘Flat Roof’ generally means any roof with a roofslope no greater than 1:20 or 3°, where lateral restraint is provided by the cladding system, eg. through fix metal liner or deck. For further advice on any aspect of the Multibeam system, please contact our Technical Department.