Curved Roofing Performance Statement
The performance of Dimond Curved Roofing Systems is covered by the statement for straight roofs together with the additional criteria set out below. Curved roofing systems are available in three basic forms:
Crimp Curved
- Available in a restricted range of metal profiles and to a minimum machine crimped radius limitation.
- Single curves, or combinations of straight, convex and concave are available, but with some restrictions that must be discussed with Dimond at the design stage of each project.
- Attention at the design and installation stages must be given to correct sheet layout, end laps, and water catchment for low pitch areas.
- Extra maintenance washing of crimp curved sheets may be required to remove dirt build-up at the crimps or in areas not naturally washed by rainfall.
- Transport and handling will limit sheet lengths and shapes and must be discussed with Dimond at the design stage of each project.
Drape Curved
- Recommended for a restricted range of profiles in metal, Duraclad and Natural Lighting materials.
- Minimum curve radius is limited by the appearance of the roof sheet.
- Roof purlin design must take into account the purlin deflection and reaction that will result from the load to hold drape curved sheet in place. As a guide this load can reach 2.5 kN/m or more on the purlin depending on radius and material.
- Water catchment for low pitch areas must be considered in relation to the sheet side laps, and may limit the maximum curve radius.
Roll Curved
- Available in a restricted range of metal profiles and to a minimum machine rolled radius for each profile and material.
- Single curves, or a combination of straight, convex and concave are available but with some restrictions that must be discussed with Dimond at the design stage of each project.
- Attention at the design and installation stages must be given to correct sheet layout, end laps, and water catchment for low pitch areas.
- Transport and handling may limit sheet lengths and shapes, and must be discussed with Dimond at the design stage of each project.
In all three curved roof systems penetrations, sheet termination (e.g. abutting walls, apex) and end lapping must be avoided in areas of the roof where the pitch is less than the minimum required for the profile.
Crimp Curved & Roll Curved Roofing System Design
Combinations of curves and straight sections must be laid out on the roof to fit purlin locations where fastening and sheet end laps occur. Basic rules that govern the design are:
- Straight tails on curves must span across at least two purlins.
- Maximum length from curve to tail end is normally limited by transport and handling to 6m.
- Laps must be in areas of roof pitch that meet the minimum pitch requirement for the profile.
- A roof shape transition from convex to concave curves must have a straight section of at least 300mm located over a purlin to allow fixing.
Profiles and material available for crimp curved systems are
| Profile | Material | BMT (mm) | Minimum Radius (mm) |
| LT7* | Steel G550 | 0.40 | 400 |
| LT7* | Steel G300 | 0.55 | 400 |
| LT7* | Aluminium H34 | 0.90 | 400 |
| V-Rib | Steel G550 | 0.40 | 400 |
| V-Rib | Steel G300 | 0.55 | 400 |
| Styleline* | Steel G550 | 0.40 | 400 |
| Styleline* | Steel G300 | 0.55 | 400 |
| Styleline* | Aluminium H34 | 0.90 | 400 |
Profiles and materials available for roll curved systems are
| Profile | Material | BMT (mm) | Minimum Radius (mm) |
| Corrugate | Steel G300 | 0.40 | 450 |
| Corrugate | Steel G300 | 0.55 | 450 |
| Corrugate | Aluminium H36 | 0.70 | 1200 |
| Corrugate | Aluminium H36 | 0.90 | 450 |
*Note that 0.40mm LT7 and Styleline are not recommended for crimp curing to a radius greater than 900mm
