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How to build a criblock retaining wall

There is a process on how to build a criblock retaining wall.

Select the retaining wall type for the situation and budget. Use our retaining wall design and price guide.
Design the retaining wall. Learn more about retaining wall design.
Schedule the materials and organise the labour and plant.
Build the retaining wall.

There are several types of retaining walls, each being different to build. Click on the links below to learn how to build that type.

The criblock retaining wall build process

Criblock retaining walls are build using concrete or timber cribs (frames). The cribs use stretches and headers, The width of the crib frames are normally 1.2m. The depth of the criblock wall can be 600mm, 900mm, 1200mm or 1500mm. On large walls the cribs are doubled up to make a wider base. The design of a criblock is based on an inclined gravity wall. Before any work can begin a design is required to calculate the width of the wall. If in doubt, ask.

The build process

Step 1) Excavation
Excavate the area where the wall is to be constructed. Rake back the earth to a safe slope. Excavate the foundation and construct it as detailed by the engineer. Proof roll the formation, excavate and fill any soft spots with stone.

Criblock earthworks

Step 2) Foundation
Excavate the foundation, place formwork to make sure the foundation is flat and cast to the correct angle. Construct the foundation as detailed by the engineer.

Criblock foundation

Step 3) The First layer of stretchers.
Lay them out and level them with packers of slate or a mortar bed if the foundation is slightly out of level. Getting the first layer to the line and level is important to make construction easier later. The second layer is the headers that fit over the joints of the stretchers.

Concrete criblock retaining wall

Step 4) Install the drain.
Once the first few layers of the criblock are installed, it is an excellent time to install the drain. Install a 100, 150, or 200 mm perforated land drainage pipe. The size will depend on the wall size.

Lay the drain on a layer of Terram T1000 and 200m depth of clean stone and wrap the Terram around a 600mm x 600mm pipe surround.

The Terram will stop any fines clogging up the stone and drain.

How to build a concrete criblock retaining wall

Step 5) Stone Filling
Once the first few layers of criblock units are in place, fill the crib voids with stone. Use a good quality hard angular 40-50mm stone. The mass of the stone needs to be 1800kg/m3 or more, as this is the mass normally allowed for in the design calculations.

How to build a crib retaining wall

Step 6) Build to completion.
Continue to build the criblock wall per the engineer’s details. Build the wall in layers, fill the crib voids and backfill behind the wall as you go.
Backfilling as you go will give the wall stability.

On completion, tidy up the earthworks and clear away any surplus/waste materials.

How to build a criblock retaining wall