Structure
Frame Design
AS 1170.0 Structural Design Actions – General Principles defines the loads that a structure is subjected to.
Wall and ceiling system framing must be designed according to the relevant standard:
- AS 1684 Residential Timber Framed Construction
- AS 1720 Timber Structure
- AS 4100 Steel Structures
- AS/NZS 4600 Cold Formed Steel Structures
- NASH Standard for Residential and Low-rise Steel Framing, Part 1
- AS 3623 Domestic Metal Framing
- AS/NZS 2785 Suspended Ceilings.
Internal Walls and Ceilings
All internal wall systems and wall height tables published in this manual comply with the relevant section of BCA Specification C1.8. Wall heights for fire rated systems have been verified by independent fire engineers.
As a minimum, all internal wall systems published in this manual comply with the deflection under the Uniformly Distributed Load (UDL) requirements from BCA Specification C1.8. The allowable deflection under a static pressure of 0.25 kPa must be less than either the wall height ÷ 240 or 30mm.
Some applications have additional requirements such as the walls of shafts and fire isolated exits. Unusually strong wind loading conditions such as those experienced in tall buildings may require internal walls and ceilings to be designed to higher pressures than the standard 0.25 kPa [Refer to BCA].
Frame fasteners
Ensure fasteners used to fix top and bottom track/plate are appropriate for the Uniform Distributed Load (UDL) on walls. At 600mm fastener centres and UDL of:
- 0.25 kPa, the fasteners must withstand a shear load of 0.75 kN.
- 0.35 kPa, the fasteners must withstand a shear load of 1.1 kN.
External walls and ceilings
Frame design of external wall systems must consider local environmental loading conditions and applied vertical load on the studs. [REFER TO AS 1170.0 Structural Design Actions – General Principles].
Control joints
Control joints allow for any building movement resulting from influences such as moisture migration, loading, structural movement and foundation settlement. Cracks in plasterboard and plasterboard joints should be eliminated by using control joints and the correct installation techniques.
Control joints must be installed in plasterboard walls and ceilings at:
- Maximum 12 metre intervals
- Control joints in the structure
- Any change in the substrate material.
Distance between control joints may need to be reduced to less than 12 metres due to conditions such as large temperature or humidity variations.