A crib wall is a precast concrete gravity retaining wall built from two types of interlocking members: stretchers running parallel to the wall face and headers running perpendicular to it. The members stack in alternating courses to form an open lattice. The cells of the lattice are filled with compacted granular material, and the combined mass of concrete plus fill resists the lateral earth pressure of the retained soil through gravity alone, with no internal reinforcement.

When are crib walls used?

Crib walls are most economical for short walls (typically up to 6 metres), landscape and amenity applications, walls in tight sites with limited access for cranes (members are small enough to lift by hand or small machine), walls in seismic zones (the system is flexible and dissipates dynamic energy), and walls where the permeable face is acceptable or even desirable (free drainage, vegetation in the cells).

How does a crib wall compare to MSE and RC walls?

Crib walls win for very short walls (below 4 m) where the simple interlocking system beats both MSE and RC on cost. MSE walls take over for medium and tall walls (5 to 30 m) on cost and footprint. RC walls remain competitive for short walls with architectural finish requirements or basement integration. For walls above about 6 m, crib walls become uneconomic because the cross-section grows quadratically with height while MSE grows linearly.

Wall-type deep dive

Crib wall: interlocking precast gravity wall explained.

The crib wall is one of the simplest gravity retaining wall systems and one of the oldest engineered. Precast concrete stretchers (longitudinal members parallel to the wall face) and headers (transverse members perpendicular to the face) stack into an interlocking lattice, the spaces in between are filled with granular material, and the whole assembly behaves as a permeable gravity wall. Cheap, fast to build, low-tech, and well-suited to short walls in landscape and amenity contexts. This guide covers the system mechanics, design approach, fill specification, and where the crib wall fits in 2026 Malaysian practice.

By Dr. Ir. Lai Yip Poon, Founder & Chief Designer Â· AnchorSOLÂ® Wall Sdn. Bhd. Â· ~8 min read

How crib walls work mechanically

A crib wall is fundamentally a permeable gravity wall. The combined mass of precast concrete members and granular fill in the cells provides the dead weight that resists overturning and sliding from the lateral earth pressure of the retained soil. The wall section is wider at the base than at the top (typical 1:6 batter), with the heel of the base wider than the front to provide stability.

Three mechanical elements:

Stretchers: longitudinal precast concrete members, typically 1.2 to 2.0 m long, 200 mm wide, 200 mm deep. They are the visible face of the wall on the exposed side, and they run along the back as well to retain the fill.
Headers: transverse precast concrete members, typically 1.0 to 1.5 m long, 200 mm by 200 mm. They tie the front stretchers to the back stretchers, forming the closed cells of the crib.
Granular fill: clean coarse aggregate (typically 19 to 38 mm crushed rock, no fines) placed in the cells of the lattice as construction proceeds.

The crib's gravity mass equals the concrete weight plus the contained fill weight, integrated over the wall cross-section. For a typical 4 m crib wall with 1:6 batter, the cross-section at the base might be 2.5 m wide with the concrete contributing 25 to 30% of mass and the fill 70 to 75%.

Design approach for crib walls

The design treats the assembled crib as a monolithic gravity wall and runs the standard checks:

Sliding along the base: net horizontal force from active earth pressure must be less than friction at the base times the total weight. Working-stress FoS at least 1.5.
Overturning about the toe: restoring moment from total weight must exceed overturning moment from active pressure. FoS at least 2.0.
Bearing capacity: maximum bearing pressure under the base less than allowable. FoS at least 3.0.
Global slope stability: standard slope-stability analysis with the crib included as a gravity element.
Concrete member integrity: each stretcher must carry the soil pressure between supporting headers (typically a simple beam with 1.0 m span). Each header must carry the tie-back force from stretchers. Both designed as plain or lightly-reinforced concrete to BS 8110.

Standard reference: BS 8002:2015 for general retaining wall design plus manufacturer technical guidance for the specific crib system.

Fill specification for crib walls

The cells of the crib must be filled with material that:

Drains freely: prevents water pressure build-up in the cells
Does not migrate: stays in the cells over time, no fines escape through the spaces between members
Compacts to high density: maximises the gravity mass per unit volume of cell
Has high friction angle: develops shear resistance at the base of the wall

Typical specification: clean coarse aggregate, 19 to 38 mm nominal size, no fines, friction angle 38 degrees and above when compacted. In Malaysian practice, washed crushed granite or limestone meeting this spec is readily available at competitive cost.

Crib wall versus MSE and RC: the cost crossover

Wall height	Crib wall typical cost RM per m^2	RC cantilever typical RM per m^2	MSE wall typical RM per m^2
1.5 m	350 to 550	450 to 650	600 to 850
3 m	500 to 750	600 to 850	700 to 950
5 m	800 to 1,200	900 to 1,400	800 to 1,150
6 m	1,100 to 1,600	1,200 to 1,700	900 to 1,200
8 m	1,600 to 2,300 (uneconomic, typically not built)	1,400 to 2,100	1,000 to 1,400

Crib walls win clearly below 4 metres. Between 4 and 6 metres, the cost gap narrows and MSE starts to compete on cost and offers a better long-term durability profile. Above 6 metres, crib walls are typically not built; MSE is the default.

Applications where crib walls suit Malaysian projects

Landscape and amenity walls

Township boundary walls, garden walls, lakeside amenity walls, walls within parks and recreational areas. Crib walls accept vegetation in the cells, producing a "green wall" finish that suits soft landscape contexts.

Tight-access sites

Crib wall members are small enough to lift by hand or by a small loader. They work on sites where MSE precast facing panels (which are large and heavy) cannot be delivered or lifted into position.

Slope toe protection

Short walls at the toe of slopes, often combined with bioengineering or vegetation on the slope face above.

Seismic-sensitive zones

Crib walls are inherently flexible (joints between members allow some movement) and dissipate dynamic energy through internal friction. Used in moderately seismic regions for short retaining structures.

Temporary and demountable walls

Crib walls can be disassembled and re-erected at a different location. Used for staging works, temporary retention during construction, and projects with potential future expansion.

Limitations and where crib walls do not fit

Tall walls above 6 to 8 metres: cross-section grows too large, MSE more economical
Architectural facade walls: the open crib face is industrial-looking, not appropriate for prestige projects where a smooth precast or architectural finish is required
Bridge abutments and structures supporting external loads: crib walls have limited capacity for concentrated loads from bridge bearings, building columns, or other structures on top
Highly cohesive backfill behind the wall: crib walls assume the retained soil has predictable active earth pressure; cohesive backfill with cracking or shrink-swell is problematic
Marine and aggressive environments: not commonly used in marine due to concrete cover and durability concerns at the open face