Block Retaining Walls: Besser, Heron, and Interlocking Systems

Block Retaining Walls: Comparing Major Systems

Block retaining walls are one of the most adaptable and widely used wall types in Melbourne. With multiple block systems available — from heavy-duty besser blocks to lightweight interlocking units — there is a block solution for virtually every retaining wall project. This guide compares the major block systems to help you choose the right one for your needs.

Besser Blocks (Concrete Masonry Units)

Besser blocks are the workhorses of the block retaining wall world. These hollow concrete masonry units are laid in courses like brickwork, then reinforced with vertical steel bars and filled with concrete grout to create a solid, monolithic structure.

Structural strength: When fully grouted and reinforced, besser block walls can handle very heavy loads. They are used for walls from one metre to several metres in height.
Finish: Besser blocks are typically rendered and painted for a clean, contemporary appearance. They can also be left exposed for an industrial look.
Cost: $400 to $700 per lineal metre installed, including reinforcement, rendering, and drainage.

Heron Blocks

Heron blocks are a proprietary interlocking block system designed specifically for retaining walls. They feature a tapered shape that creates an automatic setback (batter) as the wall rises, improving structural stability without the need for mortar in many applications.

Ease of installation: The interlocking design speeds up construction compared to traditional besser block walls.
Appearance: Heron blocks have a textured face that provides a finished look without rendering.
Height range: Suitable for walls up to approximately 1.5 metres without geogrid reinforcement; taller walls are possible with engineering and geogrid.
Cost: $350 to $600 per lineal metre installed.

Interlocking Block Systems

Beyond Heron blocks, several other interlocking systems are available in Australia from manufacturers such as Adbri Masonry, Baines, and Austral. These systems use lips, pins, or channels to connect courses mechanically without mortar. View all concrete block wall options for a detailed comparison of available systems.

Design flexibility: Interlocking blocks suit straight, curved, and tiered wall designs.
DIY-friendly for low walls: Walls under 500mm can sometimes be installed by handy homeowners, though professional installation is always recommended for quality and compliance.
Cost: $300 to $550 per lineal metre installed for standard heights.

Choosing Between Block Systems

Consider these factors when selecting a block type:

Wall height and loads: For walls over 1.5 metres or walls supporting driveways, structures, or slopes, fully reinforced besser blocks are typically the best option.
Aesthetics: If you want a finished face without rendering, choose Heron or split-face interlocking blocks. If you prefer a smooth rendered finish, besser blocks are ideal.
Budget: Interlocking blocks are the most cost-effective for low walls. Besser blocks cost more but provide superior strength for taller structures.

Block Wall Cost Comparison

Read our block wall cost guide for a side-by-side pricing comparison of besser, Heron, and interlocking block systems by wall height.

Drainage and Engineering

All block retaining walls require drainage behind the wall to prevent hydrostatic pressure buildup. A gravel drainage layer and agricultural pipe are standard. In Victoria, walls over one metre need a building permit, engineering design, and a VBA-registered builder. The Victorian Building Authority regulates builder licensing to protect consumers.

Get Expert Advice

Not sure which block system is right for your project? We connect you with licensed builders who can assess your site and recommend the best solution. Read our guide to choosing a retaining wall builder for tips on selecting the right professional. Our VBA-registered builder network provides obligation-free quotes across Melbourne.