When it comes to building a small block retaining wall, the vast choices of possible block units can be hard to sift through. If you need help breaking down some of your options, you’ve come to the right place!
In this article we will try to break down some of the differences between the available block units and give a professional engineer’s perspective on what to look for in a block unit. If you’d like to discuss your specific project or are just looking for some general information, please feel free to reach out to our engineering team, they would be happy to help!
What Options are Available?
In Alberta, the most common small block walls are constructed from one of the following products. Clicking on one of the block types below will take you to the product’s website.
Allan Block (Allan Block Wall Systems)
The Allan Block system is widely accepted as a reliable retaining wall block product by contractors and engineers. Allan Block offers an installation certification course that ensures your contractor knows the correct procedure to install a retaining wall that will meet or exceed your expectations.
Allan Block also offers many courses for engineers to understand the ins-and-outs of their product and general engineering standards and requirements in the industry. Allan Block has its own software for both the design and 3D modeling of retaining walls.
Allan Blocks are a hollow-core, dry-cast product with dimensions of approximately 200 mm (8″) high, 300 mm (12″) deep, and 460 mm (18″) long. The Allan Block Classic standard unit weighs 35 kg (75 lbs) and has a built-in batter angle (the angle of the wall face from the vertical plane) of 6 degrees. The blocks are available at the following suppliers in Calgary:
- Burnco Landscape Centre
- CLS Landscape Supply
- Expocrete
- Eagle Lake Landscape Supply
Cornerstone (Cornerstone Wall Solutions)
CornerStone’s original product, the 100 Retaining Wall block, is its most popular block. With dimensions and weight nearly identical to the Allan Block Classic block unit, these two blocks are hard to tell apart. The key to telling them apart is by looking at the face of the block: if it has a chamfer, it is an Allan Block, if it is straight, it is likely Cornerstone.
The main structural difference between Allan Block Classic and Cornerstone 100 units is in the interlock method. Cornerstone has a flat top and bottom, with two protruding bumps on its base, while the facing of the Allan Block units have their face slightly raised above the rest of the block, to allow for interlocking. The Cornerstone 100 block also has a slightly shallower batter angle of 4.5 degrees.
Keystone (Keystone Retaining Wall Systems)
The Keystone Compac block unit is another dry-cast concrete block product almost identical to the Allan Block Classic, and Cornerstone 100 units. The Compac blocks have the same dimensions and weight, but utilize the Keystone pin connection system to interlock the stacked block units.
Keystone is another widely available product in Calgary, however, in our professional experience, it is less common to find specified on a project requiring engineering than Allan Block or Cornerstone.
Pisa (RisiStone Retaining Wall Systems)
The Pisa2 block unit is slightly different than the first three blocks above in that it is a solid block (no hollow core or post holes). The block units are dry-cast like most small block units, and have an alignment “Split-Key Tongue” and “Interlocking Groove” to achieve interlock between units.
The dimensions of the Pisa2 block unit are 150 mm (6″) high, 300 mm (12″) deep, and 200 mm (8″) long. The weight of each standard Pisa2 block unit is 21 kg (46 lbs).
The Split-Key groove has a unique benefit – an adjustable batter angle. With the key left in place, the wall will build up at a batter of approximately 7.1 degrees. If the rear key is chiseled away, a near-vertical batter will be created.
Architextures (RisiStone Retaining Wall Systems)
The Architextures block unit has a different aesthetic than the first four block units described above. The available block units come in different sizes, but maintain a consistent height of 100 mm (4″) and depth of 250 mm (10″). The blocks have a length that varies from 150 mm (6″) to 600 mm (23.6″), which results in a weight from 8 to 34 kg (18-74 lbs).
The crisp edges and clean linear appearance of this block create a modern aesthetic for these walls. A batter angle of 1 degree is built-in to the tongue and groove of each block unit.
Versa-Lok (Versa-Lok Retaining Wall Systems)
The Versa-Lok unit has a height of 150 mm (6″), depth of 300 mm (12″) and a length of 400 mm (16″). The blocks are solid and have a weight of approximately 37 kg (82 lbs).
The Versa-Lok system uses slots and pins to achieve it’s engineered batter angle of 7.1 degrees.
Conclusion
At Factor Geotechnical we pride ourselves on our custom retaining wall design packages and making things as easy as possible for the builders responsible for putting your wall together. Reach out and we’ll help you out with your wall!
