Timber & steel framing manual - Double Span Rafter

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Country:

Building Type:

Wind:

Vdes(serv.) = 28m/s Vdes(ult.) = 50m/s

Height to top of roof (3m to 18m)

Region

Terrain Category

Shielding

Topographic Multiplier

In Shadow or Outer zone?

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Snow

DESIGN DETAILS

Roof Use

Span 1

The length of span 1 measured from the centre of its outer support to the centre of the central support

Maximise

Span 2

The length of span 2 measured from the centre of its outer support to the centre of the central support

Maximise

Overhang

mm Maximise

Spacing

Roof Slope

degrees

Roof

Please select your roof compostion here. Note that SpanMan automatically calculates the weight of roof battens and adds it to the roof weight. For details of weights refer to ABOUT > Technical.
Additional dead loads can also be added in the CRITERIA screen.

Ceiling

Please select your ceiling compostion here. For details of weights refer to ABOUT > Technical

Design Material

Pick 'List all suitable timber and steel sections' to design across all timber and steel sections. Alternatively design in a specific timber or steel material type. Press DESIGN to obtain sizes.

design Criteria

Main Span Deflection		Overhang Deflection
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Dead load maximum	mm	Dead load maximum	mm
Dead load span on
Live load maximum	mm	Live load maximum	mm
Live load span on
Wind load maximum	mm	Wind load maximum	mm
Wind load span on
Imposed Loads		Additional Midspan Point Loads
Additional dead load kPa Dead load in addition to the loads you have specified in the previous screen. The additional dead load depends on the roof use you selected. It include items such as wall partitions and services. Please modify this value if you wish. A list of default additional dead loads in defined in ABOUT > Technical Live load main span kPa The imposed uniformly distributed live load in the main span. This is set by the roof use you selected in the previous screen and cannot be modified. Loads are calculated in accordance with Table 3.1 of AS/NZS 1170.1:2002. Live load overhang kPa The imposed uniformly distributed live load on the overhang. This is set by the roof use you selected in the previous screen and cannot be modified. Loads are calculated in accordance with Table 3.1 of AS/NZS 1170.1:2002. Live load point load kN The imposed point live load that can occur anywhere on the span or the overhang. This is set by the roof use you selected in the previous screen and cannot be modified. Loads are calculated in accordance with Table 3.1 of AS/NZS 1170.1:2002.		Dead load kN Live load kN
Distance Between Lateral Restraints
Top mm
Bottom mm

Help

Description	You must enter a description
What is the load?	SpanMan increase member sizes in accordance with Australian Codes if the member supports brittle loads. If the manual load is one of the types in the drop down box, please selecet this type or leave the setting at Standard Material if the load is not brittle. You must enter a brittleness
Weight	kg/m2 You must enter a valid load between 1 and 10000

Rafter Double Span

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DESIGN DETAILS