Stramit® Corrugated cladding is manufactured from hi-tensile G550 BHP Colorbond® XRW steel or BHP Zinaclume® steel. In some locations galvanised and Colorbond XSE steel may be available by arrangement. Colorbond XRW (and XSE) is in accordance with AS2728 - Category 3 and, for the substrate, with AS1397. Zincalume AZ150 and galvanised Z450 conform to AS1397.
Sheeting Mass (kg/m2 of roof area)
thickness bmt
grade
Zincalume
Colorbond
Galvanised
0.42mm
550MPa
4.07
1.14
4.44
0.48mm
550MPa
4.63
4.70
4.99
0.60mm
300MPa
6.02
6.09
6.39
Spring Curving
Stramit® Corrugated cladding can be spring-curved, concave and convex, including curved ridges, provided it is sealed at the apex and within the recommended limits below:
Performance restricted
restricted by drainage at
the rainfall intensities shown
bmt (mm)
minimum radius*
lowest neutral radius
370 mm/hr
220 mm/hr
150 mm/hr
0.42
12*
25
37
63
92
0.48
10*
25
37
63
92
0.60
8*
26
37
63
92
*At these radii a maximum support spacing of 900mm applies, and limit state pressure capacities are reduced by 14% for serviceability and 7% for strength. These reductions apply proportionately up to the lowest neutral radius. Minimum 5 fasteners required per sheet at ends.
Thermal Expansion
All metal roof sheeting is subject to thermal expansion and, where there is a temperature difference between the sheeting and the structure, this needs to be accommodated. The colour of the sheeting will affect the amount of thermal expansion, and whether the sheet is flat or curved will affect its ability to resist without problems.
Sheet lengths should be limited to those shown below.
roof colour
light
dark
Flat
25
17
Spring-curved
20
17
Water Carrying Stramit® Corrugated cladding has excellent water-carrying capacity. Roof slopes can be as low as 5° for many applications. Roof run lengths are the combined lengths of all roof elements contributing to a single pan drainage path. This can include the roof length upstream of a roof penetration that concentrates flow into other pans. The table below gives slopes for 100 year return period rainfall intensity.
Photographs
