All brick products manufactured in Australia and New Zealand are classified in terms of their durability. Put simply, durability is the resistance of the brick to attack by soluble salts. Not every brick is suitable for every requirement and therefore bricks must be classified to determine their degree of resistance and their most appropriate use. According to the standard AS/NZS 4456.10 bricks are categorised under the salt resistance categories listed below. The applications where these various categories are to be used are detailed in AS 3700 - 1998, Masonry Structures.
Suitable for use in external walls exposed to aggressive environments such as:
• Walls where there is possible exposure to salts in the soil or ground water.
• Walls exposed to attack from windborne salt spray.
• Retaining walls.
Suitable for use in an external wall under ordinary exposure conditions.
Suitable for use in an external wall only above a sheet or membrane damp - proof course and below an adequate coping, roof or similar top covering, protecting the masonry.
AS3700 -1998 Specifies that exposure grade masonry must be used in severe marine environments ie.:
• Within 100m of a non - surf coast and 1km of a surf coast
• Within 1km of an industry which produces chemical pollutants
Note 1: In environments where exposure grade masonry is required the minimum mortar classification required is M4.
Note 2: Exposure grade bricks may not be suitable for use in areas subject to cyclic freezing and thawing.