Skip to content

Which Block Wall is best for your site?

Whether it’s enhancing your backyard, creating more usable space for a subdivision, or a large commercial development, retaining walls are creating value for customers every day by allowing them to gain more usable ground. Segmental block walls are fast becoming the solution of choice for many of these applications, and it’s not hard to see why. These attractive wall systems such as Allan Block and RockLok combine a unique adaptability and aesthetic appeal with rugged performance and exceptional longevity.

Block Wall Comparison

Allan Block and RockLok from Cirtex, a formidable pair!

Allan Block and RockLok are two extremely versatile options in the segmental wall market covering all applications from small landscape features through to integral bridge abutments and industrial walls in extreme applications. Each with its unique advantages and both with Cirtex’s exceptional support and backup, there is a solution to your grade change problem right here.

RockLok Wall

AB Classic, AB Vertical and AB Ashlar Blend

Firstly, let’s look at the unique benefits of the Allan Block system. Allan Block is a leader globally in this market, and we are sure you will be impressed with the range. The block is an excellent size at 435mm x 200mm with an attractive split stone face and is available in Iron Sand and Rock Salt colours ex stock, with a range of other colours available to order for larger projects. Allan Block is a hollow core block for excellent buildability, better drainage, and exceptional connection to geogrid which is verified by full-scale testing. The blocks have a unique groove and lip system to facilitate the correct placement of the blocks and provide extra shearing strength to the wall system. The blocks can be formed into curves and steps to create a genuinely appealing and practical solution. The AB Classic block can be used right through the wall for the classic block finish or combined with the Lite Stone, Junior and Junior lite blocks to make the Ashlar Blend finish with its random stone wall look.

Ashlar Blend Block Wall

When you need RockLok…

RockLok comes to the fore in some special applications where a designer prefers a more complicated connection mechanism, or steel reinforcement is required for the structure. Slightly heavier and larger than the Allan Block, the RockLok system is unique in its ability to connect with a greater range of reinforcement options. The RockLok flat block is ideal for standard geogrid connections or gravity walls, while the RockLok trench block accepts either HDPE geogrid or PET high tenacity geogrids with a positive lock system. For applications where a design code or site conditions require a steel reinforcement element, the RockLok ladder block can be paired with galvanised steel ladder reinforcement with steel pin connection to the blocks. Typical applications for RockLok include bridge abutments and very high seismic areas.

RockLok Blocks

Does my wall need an engineered design, and do I need a building permit?

These are among the most common questions to arise when planning small walls in New Zealand.

Generally a consent is not required for a retaining wall that:

  • Retains not more than 1.5 metres depth of ground.
  • Does not support any surcharge or any load additional to the load of that ground (for example, the load of vehicles).
Allan Block Wall

There are a number of other factors to be considered such as sloping ground above and below, and in practice this can be a subject of much discussion on site by the building inspector as to what constitutes a slope or a surcharge. Therefore Cirtex always recommends seeking advice from your local building control authority before building the wall.

Small block walls can sometimes be built without any additional reinforcement, but for larger walls or walls supporting a slope or other surcharge, reinforcement with StrataGrid soil reinforcement is usually required. Cirtex can offer information on wall design for scoping and costing purposes and can put you in touch with a certified professional if necessary to carry out a design analysis.

Once you are ready to start planning your new retaining wall, it’s good to make yourself familiar with the many resources available, from ideas and photos of previous projects, through to technical documents such as standard plans, reinforcement options, detailing and estimating charts. For additional information phone us on 0800 247 839 or email

Ready to get going?

Head over to the Allan Block and RockLok pages now for ideas and inspiration, and check out the colours, sizes and shapes. Let your imagination go wild and picture how you can enhance your property and gain more ground with Cirtex’s segmental block retaining systems.

About Michael Sorensen

Michael is a registered civil and geotech engineering technician with a passion for geosynthetics and the value they can add to engineering projects. Michael has been working with geosynthetics for 10 years and is dedicated to ongoing learning and sharing knowledge in this fast-moving industry.