Bar chair requirements in residential slabs and footings

10-May-2019
The SRIA has received a number of enquiries on the requirements for bar chairs in residential slabs and footings. 

AS 2870 Residential slabs and footings does not currently reference AS/NZS 2425 Bar chairs in reinforced concrete – Product requirements and test methods because AS 2870 (2011) was published before the AS/NZS 2425 in 2015. 

The SRIA has submitted a proposal to incorporate AS/NZS 2425 into the next revision of AS 2870 to the Australian Standard Committee. 

AS 3600 Concrete structures, AS 5100 Bridge design, AS 2327 Composite structures, AS 3727 Pavements Part 1: Residential  and AS 3850 Tilt-up concrete construction have all recently been revised and reference AS/NZS 2425. 

AS/NZS 2425  was proposed by the SRIA to address bar chair failures in the market and specifies product performance requirements and test methods for bar chairs and spacers in reinforced concrete.  

A bar chair is defined in Clause 3.1 of AS/NZS 2425 as 'the embedded items within reinforced concrete elements, which are used to maintain the position and cover of steel reinforcement during construction to ensure durability, strength and serviceability of the as-built elements, in accordance with the design specification'. 

This Standard now represents a consensus of the nominating organisations listed in the Standard and engineers should specify that all bar chairs and spacers supporting reinforcement comply with the requirements of AS/NZS 2425 to avoid failures of these important elements during the reinforcement fixing and concreting phase. 

The SRIA is currently revising Technical Note 3 on bar chairs to educate the market on AS/NZS 2425.