Skip to main content

Hoop iron bracings: requirements for compliance

December 01, 2019

The purpose of bracing is to enable the roof, wall and floor to resist horizontal forces applied to a building. It is therefore important that the type of bracing used will resist those forces.

Hoop iron cross bracing is a common form of bracing material, so how do you tell if the products your using is the correct one for use as a structural brace or tie down that complies with relevant Australian Standards?

NCC Evidence of suitability

The National Construction Code (NCC) at Part A5 specifies the different methods of evidence of suitability you can use to demonstrate that the material/product will meet the requirements of the NCC. One such method is a product technical statement. This statement provided by the manufacturer will specify the product, how and when it can be used and the performance requirements or relevant standards that it satisfies. 

If there is no detail on the packaging request a copy of the product technical statement and check the kN capacity to determine the product meets the requirements of AS 1684.

AS 1684 requirements 

The Standard requires that the nominal size of the metal straps is to be 30 x 0.8mm GI. The minimum grade of steel strap is to be G300 (AS 1397 Steel sheet and Strip hot-dip zinc coated or aluminium /zinc coated) and have bracing capacities of 1.5 kN/m for a tensioned metal strap and 3.0 kN/m for a tensioned metal strap with stud straps.

 Structural Bracing Metal strap 25 x 0.8 mm or 30 x 0.8 mm thick without stud straps
Australian Standard  Reference in Standard  Bracing capacity kN/m or Bracing Type 
AS 1684.2 (non-cyclonic)  Table 8.18 (b)  1.5
AS 1684.3 (cyclonic)  Table 8.13 (b)  1.5
AS 1684.4 (non-cyclonic)  Table 8.3 (b)  A

The bracing capacity in the above table is appropriate for wall heights up to and including 2700mm.

Table 8.18 (b)

Structural Bracing Metal strap 30 x 0.8 mm thick with stud straps
Australian Standard  Reference in Standard  Bracing capacity kN/m or Bracing Type 
AS 1684.2 (non-cyclonic) Table 8.18 (b) 3.0
AS 1684.3 (cyclonic) Table 8.13 (b) 3.0
AS 1684.4 (non-cyclonic) Table 8.3 (b) B

The bracing capacity in the above table is appropriate for wall heights up to and including 2700mm.

Table 8.18 (d)

Therefore to ensure your frame and in turn your bracing is meeting the timber framing standards requirements you also need to ensure your using the correct bracing materials.

Download pdf

For further clarification and information on the NCC or timber framing requirements HIA members can contact HIA’s Building Services team on 1300 650 620 or email hia_technical@hia.com