Step 1

Remove topsoil and soft subsoils

gabion foundation prep

Road base thickness

The required thickness of road base, depends on the actual site subsoil conditions.

In general you will need to remove topsoil, peaty organic material, and softer subsoils. and replace these with compacted hardfill/roadbase.

If building your wall on bedrock, you may only require 25mm of road base, to level of the base

Most gabion walls do not require concrete foundations.

gabion foundation drawing
gabion foundation gravel

Foundation testing

Small non engineered retaining walls, are unlikely to require Scala Penetrometer foundation testing, which accurately measures the subsoil bearing strength.

If you are unsure about the foundation requirements, please email us or talk to a local civil engineer.

scala penetrometer testing

Road base compaction

When placing 4" depth of road base or greater,  you will need to use a plate compactor

Proper compaction, eliminates future consolidation, and foundation settlement.

gabion foundation compaction
gabion retaining wall foundation

Sand Blind

Some contractors place thin layer of sand over the basecourse for final foundation leveling.

This should not be done on sites that have high groundwater flows.

gabion foundation on sand base

Stepped foundations

Stepping the foundation, allows walls to be built on sloping sites

stepped gabion foundation

Gabion foundation examples

gabion foundation examples

Stepped foundation example

Concrete ledges were cast into the bedrock,

The concrete foundations were based on the gabion basket sizes being installed.

stepped concrete gabion foundation

Foundation questions

If you have any other gabion foundation questions, please email us some pics of your site with your questions.

Concrete foundations

It is very rare for a gabion walls to require a concrete foundation, below is an example. If you site has groundwater issues, it may be advisable to use galv coated reinforcing steel

gabion concrete foundation
small gabion wall foundation

Double width base gabion

The extra width of the base gabion improves, wall stability, and reduces the bearing load on the subsoil,

Spreading the load over a larger area, allows gabion walls to be built on weaker subsoils without expensive foundations.

gabion foundation soft ground