Topdek® 700 Roofing

Material Specifications

Design Considerations

The minimum recommended roof pitch for Topdek 700 is one degree (1 in 60). The 700mm coverage of Topdek 700 provides easy handling and installation. Topdek 700 roofing is subject to thermal expansion, particularly on darker colours. The maximum length before an expansion joint is required is 24 metres for lighter colours, and 16 metres for darker colours.

Compliance

The Wind Capacity Tables are based on testing in accordance with AS1562.1-1992 and AS4040.0, 1 & 2- 1992. Span tables have been developed by determining wind pressures in accordance with AS4055-2006 for domestic applications and AS/NZS 1170.2:2002 for all other applications. Capacity tables are in limit state format.

Spans

Spans are determined by wind speeds for non-cyclonic areas. For domestic applications, the pressures and spans are based on a maximum: eaves height of six metres, roof pitch of 35 degrees and total roof height of 8.5 metres. For commercial and industrial applications, tables are based on a maximum overall height of ten metres and a 500 year design return period.

Roofing calculations are based on Cpe=-0.9 and Cpi=0.2, walling is based on Cpe=-0.65 and Cpi=0.2. A local pressure factor, Kl=2.0 has been used for all roofing and walling spans for both strength and serviceability limit states. Roof spans allow for loads incidental to maintenance.

All pressures have been determined assuming the wind loading in any direction is not affected by topography. The following shielding factors have been used for each of the terrain categories: Category 3 = 0.85, Category 2.5 = 0.95, and Category 2 = 1.

The carport and verandah spans only apply to structures not enclosed by peripheral walls. Spans are based on Cpn=-0.9 and Kl=1.5 applied over the entire span, and are suitable for all span types. Loads on supporting purlins may limit these spans.

Stratco can provide additional engineering advice if any design parameters vary from those above.

The values are for use with steel supports with a minimum thickness of 0.95mm, G550.

Wind Load Conversion

For domestic applications use the appropriate wind classification for the area. To read the span tables for commercial and industrial applications, select the region and category for the area, then convert it to the correct classification using table 2.0 below.

Maximum Recommended Spans

Roofing spans are limited, based on typical maintenance foot traffic. Walling spans are based on N1 (W28) wind loading. Spans are based on three fasteners per sheet, per support. The values are for use with steel supports with a minimum thickness of 0.95mm, G550.

Domestic Carport / Patio Spans

Spans are not based on fixing to clips, but on pierce fixing with two fasteners per pan, per support. The values are for use with steel supports with a minimum thickness of 0.95mm, G550.

Wind Capacities

The values are for use with steel supports with a minimum thickness of 0.75mm, G550.

Water Carrying Capacity

The peak rainfall intensities shown represent a 100 year average recurrence interval (ARI) for a five minute rainfall duration. If roof penetrations exist, the total roof run will generally be greater than the distance from ridge to eaves at the location the penetration interferes with the runoff. Contact Stratco if further advice is required.

Step One

Align the top and bottom clips of the first sheet along the purlins with the arrow pointing in the laying direction, and fasten in positions 1, 2 and 3 (refer to Step 1 below) using the number and type of fasteners specified in the span tables and table 8.0 above. Run a string line between the two clips, or use the edge of the first deck to ensure all clips are in line. Mark the top, bottom and middle purlins at one metre from the starting line and at 700mm centres across the purlins. Use these marks to keep the sheets square.

Align the remainder of the first run of clips to the string line and along the purlins. Fasten in position A, B and C (refer to Step 1 below) using the number and type of fasteners specified.

Step Two

Place the first sheet over the clips ensuring a minimum projection of 75mm at the ridge and into the gutter. Snap each rib onto the clip at every purlin using steady foot pressure, ensuring complete deck engagement at every rib on every clip, see the diagram below.

Hook the next run of clips over the last rib of the first sheet. The clips will align themselves and must be butted together for correct positioning. Align the hole with the slot and fasten at the joint first, then work along the bracket. During laying, regularly check the sheets for fanning or creep. If minor adjustment is necessary, the clips can be pulled away from the sheet while fastening.

Step Three

Place the second sheet over the clips, ensure the end of the sheet aligns with the first sheet. Snap the deck onto the clips in the laying order using steady foot pressure and fully engage the interlocking rib onto each clip. It is important to ensure the deck is engaged on each rib, on every clip, and the deck is engaged along its entire length.

Install the remaining clips and sheets. Remember to frequently check the coverage to maintain squareness and adjust for creep where necessary. At the end of the purlin, cut the clips and deck where necessary to suit. To secure the final sheet edge, cut the end off the bracket, hook over the last rib and fasten. Finally, remember to turn up the pans at the ridge and down at the gutter end.

Roof Laying Procedure

Fastener Selection

Note: The following recommendations apply to non-cyclonic areas.

• All fasteners must comply with Australian standard AS3566.1,2, Class 3.
• In the fastener screw sizes quoted above the first number equals the screw gauge; the second number is the threads per inch and the third number is the screw length.
• Self drilling and tapping screws should not use neoprene washers when securing clips to purlins.
• The minimum number of screws along the clip is three, one at each end and one centrally. For additional strength, five screws may be used.
• the above fastener sizes are suitable for fixing over an insulation blanket up to 55mm thick. For thickness up to 100mm, the next standard screw length to that indicated is to be used.

Walking on Topdek 700

When walking on Topdek 700 roofing, it is recommended you walk over the purlins to avoid any damage. Wear flat, rubber soled shoes and walk flat footed in the sheet pans only. For carport and verandah applications, use crawl boards to avoid damage during installation and maintenance.

Using Topdek 700

Stratco Topdek 700 will have a long, useful life if used according to Stratco specifications. While roofing materials in outer urban and rural areas may have a life-span in excess of 30 years, this can reduce to only a few years in coastal and industrial environments.

Zinc/al pre-painted steel should not be used in very aggressive areas such as near swimming pools and spas. It is important that dirt, soil, compost, paving sand, or other materials which retain moisture are not placed against steel sheeting. Concrete should not be poured against zinc/al material. Check with Stratco before using in these severe environments.

Incompatible Metals

The best way of reducing corrosion is to keep incompatible metals apart. Zinc/aland pre-painted steel cannot be used with lead, copper and monel. Galvanised steel and pure zinc material can be used with zinc/al, but you must avoid water run-off from zinc/alonto galvanised material. Fixings such as rivets and self-drilling screws must be compatible with the material they are fixing.

Handling and Cutting

For safety, wear gloves when handling Topdek 700. Ensure your hands or gloves are clean, especially when handling zinc/alwhich can mark. Use a coloured pencil for marking steel, as lead or black pencils contain graphite which promotes rusting. Topdek 700 is best cut using tin snips, but for larger cuts it may be necessary to use a power saw with a steel cutting blade or a power nibbler. Avoid using abrasive discs as they can cause burred edges and coating damage. Where possible cut sheets on the ground, and always clean off any swarf and metal filings progressively during the installation. Dispose of off-cuts carefully.

Insulation and Sealants

The use of blanket insulation is recommended in domestic roofing to assist in temperature, condensation and sound control. Topdek 700 can be used with an insulating blanket up to 55mm thick. Increased thicknesses require longer fasteners and greater care when installing.

When choosing a silicone sealant, ensure it is suitable for roofing and guttering use and of a non-acetic, amine free, neutral cure type. Sealants that smell of ammonia, vinegar or lemons are not usually suitable.