In landscaping and hardscape design, steps are more than just a practical feature, they are an opportunity to add structure, safety, and visual interest to sloped spaces. When built with the Allan Block retaining wall system, you can achieve strong, consistent, and long-lasting steps.
Below, we outline the recommended process for constructing retaining wall steps -ensuring each course is level, stable, and built to last.
Step 1: Excavate and Prepare the Base
Begin by excavating to the required depth and width for each step riser. Use a plate compactor to thoroughly compact the entire area - a well compacted base helps prevent future movement or settlement and ensures the structure remains solid.
Step 2: Check for Level
Before moving forward, check that the excavated area is level. Even a small discrepancy can affect alignment and step uniformity further up the wall. Taking the time to get this right now will make the rest of the installation much smoother.
Step 3: Place Granular Aggregate Fill
Add 150mm of well-graded granular aggregate to the first step area and rake it smooth. Compact the fill carefully and recheck for level. Because stairs experience additional pressure over time, extra compaction is essential to minimise future settlement.
Step 4: Install the First Course of Blocks
Set the Allan Block retaining wall directly on the compacted granular fill, leaving a 150mm backfill zone behind the blocks for drainage and support.
Check each block for level and alignment as you go - precision here will ensure a clean, professional finish throughout the build.
Step 5: Fill and Backfill
Fill the block cores, along with all spaces in front of and behind the blocks, using granular aggregate. Then backfill the excavated area behind the riser to establish a solid, level base for the next step. For best results, backfill and compact in 100mm lifts. This approach delivers optimal compaction and long-term stability.
Step 6: Compact and Level the Fill
Rake the surface smooth and compact the area using a plate compactor. Your first pass should be made directly on top of the blocks, moving parallel to the wall face. Proper compaction at this stage locks everything in place and ensures the steps remain stable and level.
Step 7: Repeat for Additional Steps
Continue this process for each subsequent step until the desired stair height is reached. Consistency in preparation, alignment, and compaction is key to a reliable, long-lasting result.
How Many Steps Will You Need?
To calculate the number of steps required, measure the total rise of your slope in millimetres and divide by 200mm, which represents the height of one Allan Block step.
For example, if your total rise is 1,000mm, you’ll need five steps.
Building with Confidence
Constructing steps with the Allan Block Retaining Wall System provides a robust solution that performs as well as it looks. By following this methodical process from careful excavation to precise compaction, you can achieve perfectly aligned, structurally sound steps that enhance both the usability and aesthetics of your outdoor space.
Get in touch with our team today to discuss your project and see how Colinwell can help turn challenging sites into long-lasting retaining wall solutions.
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