Topspan^®

Topspan ^® Profile Performance
 

Topspan^®is a high rib roofing profile that combines wide coverage with long span capabilities. It has a curved rib top and a bold shape. These attributes allow Topspan^® to achieve economy, style and ease of installation. Topspan^® is ideal for large commercial and industrial applications and the profile is also readily available in Dimond’s range of natural lighting systems.

Sheet Tolerances
Cover: ± 5mm - Sheet length: +10mm, -0mm (steel)
Cover: +10mm, -15mm - Sheet length: +0mm, -15mm (aluminium)

Roll-forming facility location: Christchurch

Crimp curving facility location: N/A

Manufacturing location for DuraClad®: Auckland

Sheet lengths: Topspan® is custom run to order.

Where long sheets are used consideration must be given to:

• Special transportation licences for sheet lengths over 25m
• Site access for special lifting equipment
• Fixing techniques to accommodate thermal expansion.

DIMOND TOPSPAN® LIMIT STATE LOAD / SPAN CAPACITY CHART

(span in mm, distributed serviceability loads in kPa)
 

*Available only on request, subject to minimum order quantities. Check availability with Dimond.

Notes

1. In Restricted Access Roof and Non-Access Roof & Wall applications, spans exceeding the maximum values shown should not be used. The maximum spans for Restricted Access Roofs are based on static point load testing as a guide and are further limited by practical experience of roof performance under dynamic foot traffic loads. For Non-Access Roof & Wall applications, the maximum spans are limited to ensure satisfactory appearance for wall cladding.
2. Loads given are based on 4 screw fasteners/sheet/purlin.
3. Loads given are limited to a maximum of 4.5 kPa. If design requirements exceed this limit, contact Dimond for specific advice.
4. Duraclad®
   – Serviceability Limit State loads are not applicable to the Duraclad® material, as it does not experience permanent deformation.
   – System must include Safety Mesh if intended for use as a Restricted-Access roof. Refer Section 2.2.1.8 of Technical Manual.
5. N/R = not recommended.
6. End span capacities given in this table are based on the end span being 2/3 of the internal span.
7. Design Criteria for Limit State Capacities
   1. Serviceability Limit State (SLS Design)
      No deflection or permanent distortion that would cause unacceptable appearance, side lap leakage or water ponding, due to foot traffic point loads, inward or outward wind loads or snow loads.
   2. Ultimate Limit State (ULS Design)
      No pull through of fixings or fastener withdrawal resulting in sheet detachment due to wind up-lift (outward) loads.
8. System Design
   The span capacity of the roofing or cladding profile is determined from the Load Span Table, using the section of the chart appropriate to the grade and type of material, and the category of serviceability selected from the two categories above. Serviceability loads have been derived by testing according to NZMRM procedures. To obtain an ultimate limit state load, we recommend factoring the serviceability load by 1.4 in line with NZMRM guidelines. Note: The capacities given do not apply for cyclone wind conditions.
   
   Serviceability Requirements
   While these categories are provided for design guidance to meet the serviceability limit state criteria, foot traffic point load damage may still occur if point loads are placed carelessly.
   
   Service Category
   Refer to MRMCOP 3.7.4 Roof Traffic. The designer must consider the degree and type of foot traffic expected on a roof. The following requirements are subjective standards and must be considered in line with customer expectations, building use, and type. More robust design than specified below (such as reducing purlin spacing or adding protection from mechanical action) is required for roofs that are regularly accessed, used as staging by subsequent trades, or areas adjacent to access points, particularly step-down access.
   
    
9. Wind Pressure Guide
   As a guide for non-specific design the following S.L.S. design loads in accordance with the MRM Roofing Code of Practice can be used for buildings less than 10m high, otherwise AS/NZS 1170.2 should be used
   Low wind zone = 0.68kPa, Medium wind zone = 0.93kPa, High wind zone = 1.32kPa, Very high wind zone = 1.72kPa and Extra high wind zone = 2.09kPa.

Topspan^® Fastener Design

The durability of the fasteners should equal or exceed that of the material being fastened, and the fastener metal or coating must be compatible with the cladding material if in contact. Refer to NZS E2/AS1 table 20 for compatibility requirements. 

The minimum embedment of 30mm is the requirement for screws fixing into timber and minimum of three threads to pass through steel. When fastening through cavity battens, thermal break materials etc ensure the length of the screw is increased to accommodate the extra material

Use in serviceability categories (1) or (2) can allow the reduction of fasteners to 2 screw fasteners/sheet/purlin by using 2 fasteners/sheet/purlin. If this is done, the distributed load capacities given in the chart should be reduced using a multiplying factor of 0.5.

Long spans may require the specification and use of side lap stitching screws – see Section 2.3.2C Installation Information: Layout and Fastening Technical Manual.

Design Example

 

Restricted access roof, 0.55mm G550 steel Topspan® has a maximum end span of 2900mm and a maximum internal span of 4300mm. The following distributed load capacities apply.

Fastener Layout Options

Top Span Commercial Roofing

Top Span Commercial Cladding Vertical

Top Span Commercial Cladding Horizontal