Update for Architects - AS 4773 - masonry in small buildings

It has been recognised for some time that the design rules and details for masonry housing, and other similarly sized small buildings, in AS 3700 Section 12 are quite restrictive. Standards Australia is drawing close to the publication of AS 4773.1 Masonry for small buildings - Part 1 Design and AS 4773.2 Masonry for small buildings - Part 2 Construction. These two standards will provide designers and builders with a practical design tables and details that cover all aspects of the design and construction of unreinforced masonry (brick veneer, cavity masonry, and single-leaf masonry) and reinforced single-leaf hollow blockwork for houses and other small buildings. Some of the more significant improvements over AS 3700 Section 12 are discussed below.

Control Joint Spacing Clay brickwork expands and concrete blockwork contracts. Reactive clay foundations heave and shrink, inducing cracks in both types of masonry superstructure. The incorporation of control joints (including articulation joints, expansion joints and/or contraction joints) is an important means of limiting and controlling cracking in both brickwork and blockwork. The current masonry control joint spacings in AS 3700 Section 12 are not practical. AS 4773 provides modified spacing, recognising the practical differences between veneer and cavity construction, the effect of widow and door openings and the need to stabilise corners while simultaneous catering for "push past" of expanding clay brickwork.

Hold-down Capacity of Anchorages
AS 4773 provides details and design capacities for roof anchorages in both unreinforced cavity masonry (cavity brickwork) and reinforced single-leaf hollow blockwork, for high wind applications.

Steel Lintel Tables
Steel lintels are often used to bridge openings over windows and doors in masonry veneer and cavity masonry construction. The design criteria for such lintels have now been clarified and the tables expanded.

Reinforced Hollow Concrete Blockwork Lintel Tables
Reinforced hollow concrete blockwork lintels bridge openings over windows and doors while simultaneously forming part of the bond-beam "ring beam" that ties a reinforced blockwork building together to form a "stiff box." A wide range of reinforced masonry lintel tables, for both wind uplift and downwards gravity load are provided.

Flashing Details
It is important that the building designer understand, and communicate clearly to the builder, the limitations and practices in regards preventing water penetration to the inside of buildings. The range of flashing details has been expanded to cover all common housing applications. For the complete background, tables and details, please refer to website