Interlocking Block Retaining Walls in Burnaby

Interlocking block retaining walls — also known as segmental retaining walls — are the most widely used engineered wall system for residential applications in the Lower Mainland. Systems like Allan Block, Versa-Lok, Anchor, and similar brands have published load tables and design guides that make them suitable for walls up to 3–4m in height (and higher with geogrid reinforcement).

Unlike mortared concrete block walls, segmental systems are dry-stacked. The blocks interlock through a pin-and-groove or set-back mechanism and rely on a designed backward lean (batter) to direct their own weight into the retained soil. Drainage aggregate placed behind the wall provides both drainage function and load transfer.

These systems became popular for good reason: they're installed faster than mortared walls, tolerate minor differential settlement without cracking, and the published engineering documentation makes permit applications straightforward.

How Segmental Retaining Walls Work

The structural principle behind a segmental retaining wall is different from a gravity wall or a cantilever wall. Each course of block is set slightly behind the course below, creating a slight backward lean (typically 6–12 degrees from vertical). This batter means the wall is leaning into the soil it's retaining, and the weight of the wall mass helps resist the overturning forces from the soil.

For walls under about 1.2m, the wall mass alone provides enough resistance. For taller walls, geogrid reinforcement — horizontal layers of high-tensile plastic mesh — is embedded between courses and extends back into the retained soil. This connects the wall to a large mass of reinforced soil, turning the whole assembly into a gravity structure. Geogrids are specified in the manufacturer's design charts and are required for any wall above about 1.0–1.2m depending on the block system and site conditions.

The base course is critical. It's set in a compacted granular pad, typically recessed below grade so that the first visible course sits at grade level. Proper base preparation is what determines whether the wall will move over time.

Allan Block, Versa-Lok, and Other Systems We Install

We work with all major segmental retaining wall systems. Allan Block products are widely available through landscape suppliers in the Lower Mainland and come in several face textures and sizes. The AB Classic, AB Lite, and AB Jumbo series cover a broad range of wall heights and aesthetic preferences.

Versa-Lok is another engineered system with a distinctive through-pin interlock mechanism. It's known for its consistent block geometry, which makes it well-suited for curved walls and corners.

Anchor Wall Systems, Belgard, and various masonry producer systems are also available in the Lower Mainland and can be specified to match existing hardscape materials on your property.

If you have an existing interlocking block wall that needs repair or extension, we'll match the block type wherever possible. Bring us a sample if you're not sure of the brand.

When Geogrid Reinforcement Is Required

Geogrid is a horizontal reinforcement layer — typically a high-density polyethylene (HDPE) mesh — placed between block courses and extended back into the retained soil behind the wall. It mechanically connects the wall face to a large mass of compacted soil, dramatically increasing the wall's resistance to overturning and sliding.

Most segmental block manufacturers' design charts require geogrid for walls over about 1.0–1.2m in height, and for any wall with surcharge loading (driveways, patios, structures) within the failure plane behind the wall.

The length and vertical spacing of geogrid layers is determined by the manufacturer's design guide and, for permitted walls, by an engineer. We pull up the manufacturer's design charts for every project and flag when engineering is required.

Geogrid installation requires excavating back into the slope to accommodate the reinforced zone — typically 60–80% of the wall height in horizontal extent. This is more intrusive than building a wall without reinforcement, and it's a factor that affects cost and scheduling.

Curves, Steps, and Corners

One advantage of segmental block systems is their adaptability to non-linear layouts. Most block types can be cut with a masonry saw to form tight curves. Corners are formed using corner units or careful cutting to maintain interlock.

Curved walls are common in residential landscaping — a sweeping curve at the edge of a sloped garden looks far more natural than a right-angle layout. Blocks are cut or tapered to achieve the desired radius, and the geogrid layers follow the curve behind the wall.

Steps integrated into the wall are also straightforward with segmental systems. Cap units and step units are manufactured for most block lines and create a clean, consistent look.