Cantilever Details

It is possible to cantilever UltraZED Purlins over the gable frame to form a canopy detail providing the following design criteria is adhered to:-

Purlins should be installed in one continuous length encompassing the penultimate and/or the end bay together with the required overhang and the sheeting must provide full lateral restraint to the Purlin section. It is necessary for the cantilever ends of the Purlin to be restrained against rotation and movement, this is achieved by:-

1.Fixing Cleader Angle to the top and bottom flanges at the end of the overhang and over the apex.

or

2.Where the cladding does not require cleader a SRS Type Strut should be fitted between Purlins at the end of the overhang and tied over the apex.

In both cases if the roof slope exceeds 30º or is of mono-pitch construction a Diagonal Purlin Brace assembly should be used to prohibit down slope movement.

Deflection

The published load tables limit deflection to not more than SPAN/180.

As a consequence the cantilever deflection should also reflect this limitation. The overhang length therefore should be no more than 25% of its backing span, alternatively use UltraPRO. Design Software.

For other design cases or heavy loads such as Tiled Roof construction we recommend consultation with our technical department.