Retaining Wall Rebar Guide

What Size Rebar for a Retaining Wall?

Q: How deep should rebar be embedded in the footing?

Starter bars must achieve the full design lap length — generally at least 40 × bar diameter. For Ø12 mm bars that is a minimum 480 mm embedment.

Practical B500B bar-diameter and spacing guidance for gravity, cantilever and block retaining walls — with a worked material estimate and DIN 488 / EN 10080 supply information.

Request a Quote → View Applications

DIN 488 · EN 10080 Mill Test Certificate Worldwide export

Why Retaining Wall Rebar Sizing Matters

A retaining wall must resist both the lateral earth pressure behind it and the vertical load of any surcharge above. Under-reinforced walls can crack, rotate or collapse; over-reinforced walls waste material and cost. Getting the bar diameter, spacing and concrete cover right from the start is therefore a structural and economic necessity.

The guidance below is based on common practice for residential and light civil retaining walls reinforced with B500B ribbed bar to DIN 488 / EN 10080. B500B delivers 500 MPa minimum yield strength, k ≥ 1.08 and Agt ≥ 5.0 % — the standard high-ductility grade used across Europe for cast-in-place reinforced concrete. Always have a structural engineer verify your specific design, especially for walls taller than 1.2 m or walls carrying significant surcharge.

ⓘ Indicative figures. Wall geometry, soil type, surcharge and local seismic zone all affect actual reinforcement requirements. Confirm your design with a qualified structural engineer before ordering.

Typical Rebar Sizes for Retaining Walls

General guidance by wall height — B500B ribbed bar, cast-in-place concrete, normal soil conditions.

Wall Height	Vertical Bars (stem)	Horizontal Bars (shrinkage/temp)	Footing Bars	Typical Spacing
Up to 0.6 m	Ø10 mm	Ø8 mm	Ø10 mm	200 mm c/c
0.6 – 1.0 m	Ø10–12 mm	Ø8 mm	Ø12 mm	150–200 mm c/c
1.0 – 1.5 m	Ø12 mm	Ø10 mm	Ø12–14 mm	150 mm c/c
1.5 – 2.0 m	Ø12–16 mm	Ø10 mm	Ø14–16 mm	150 mm c/c
2.0 – 3.0 m	Ø16–20 mm	Ø12 mm	Ø16–20 mm	125–150 mm c/c

Indicative figures for normal granular backfill, no surcharge, free-draining wall. Engineering design required for all structural applications.

Bar Properties: B500B Reference Table

Use the weight formula kg/m = d²(mm) × 0.00617 for quick quantity estimates. Cross-sectional area A = π/4 · d².

Dia (mm)	Weight (kg/m)	Section (mm²)
8	0.395	50.3
10	0.617	78.5
12	0.888	113
14	1.21	154
16	1.58	201
20	2.47	314

How to Lay Out Rebar in a Retaining Wall

Stem reinforcement

Vertical bars run from the footing up through the stem — they carry the bending moment created by earth pressure. Place the main vertical mat on the tension face (the earth-side face of a cantilever stem). Concrete cover is typically 40–50 mm in exposed or below-grade conditions per Eurocode 2 (EN 1992-1-1) to protect against carbonation and chloride attack.

Horizontal distribution bars

Horizontal bars tied to the verticals control shrinkage cracking and distribute load. A minimum cross-sectional area of 0.1–0.2 % of the gross section is common for temperature and shrinkage reinforcement. For a 200 mm thick wall, Ø8 @ 200 mm c/c (As ≈ 251 mm²/m) is a typical minimum.

Footing (base slab)

The footing resists overturning and sliding. Bars in both directions — longitudinal and transverse — are standard. The toe of the footing is often more heavily reinforced than the heel, depending on the soil bearing pressure distribution. Starter bars from the footing must extend into the stem with adequate lap length (typically ≥ 40 × bar diameter per DIN 488 lap rules).

Concrete cover

Minimum cover to rebar in a retaining wall: 40 mm where concrete is cast against ground; 30–40 mm in sheltered exposed conditions. Check the site-specific exposure class (XC, XS, XD, XF) under Eurocode 2.

Worked Estimate: 1.5 m Cantilever Retaining Wall (10 m run)

The following is an indicative material take-off only — confirm with your structural engineer’s drawings.

Stem vertical bars: Ø12 @ 150 mm c/c, 1.7 m long (including 200 mm footing embedment). 10 m ÷ 0.15 m = ~67 bars × 1.7 m × 0.888 kg/m ≈ 101 kg
Stem horizontal bars: Ø10 @ 200 mm c/c over 1.5 m height = 8 bars × 10.2 m × 0.617 kg/m ≈ 50 kg
Footing bars (longitudinal + transverse): Ø14 @ 150 mm c/c in both directions across a 0.6 m wide × 10 m long footing ≈ 90 kg
Starter bars & laps: add ~10 % wastage/laps ≈ 24 kg
Indicative total: ~265 kg (this is an estimate; actual tonnage depends on engineering design)

ⓘ Indicative estimate only. Wall geometry, soil type, surcharge loads and engineer’s design will determine the actual reinforcement schedule. Always verify quantities from approved drawings.

We supply B500B in standard 6–12 m lengths or as cut-and-bend shapes to your engineer’s bar-bending schedule. For mesh-reinforced gravity walls, see our reinforcing steel mesh range.

Frequently Asked Questions

What is the minimum rebar size for a retaining wall?

For walls up to about 0.6 m tall under normal residential loads, Ø10 mm B500B vertical bars at 200 mm centres is a widely used minimum. Below about 0.5 m, reinforced mesh may suffice. However, there is no universal minimum — the correct size is always determined by structural calculation for the specific height, soil and surcharge.

Should I use B500B or B500A rebar for a retaining wall?

B500B is the standard choice for cast-in-place retaining walls. Its high ductility (k ≥ 1.08, Agt ≥ 5.0 %) provides superior resistance to cracking and redistribution of stresses, which is important in a structure subject to variable earth pressure. B500A (coil/mesh grade) is more suitable for prefabricated mesh reinforcement in lighter applications.

What rebar spacing should I use for a retaining wall?

150 mm centres for vertical bars in walls from 1.0–2.0 m tall is typical under normal conditions. Walls taller than 2.0 m or those carrying vehicle surcharge may require 100–125 mm spacing or larger bar diameters. Always follow your structural engineer’s specification.

How deep should rebar be embedded in the footing?

Starter bars from the footing into the stem must achieve the full design lap length — generally at least 40 × bar diameter. For Ø12 mm bars that is a minimum 480 mm embedment. The footing itself should have a minimum 75 mm cover to bars at the underside where cast against blinding concrete.

Can Steel Rebar Germany supply cut-and-bend retaining wall rebar?

Yes. We supply B500B bar in standard stock lengths (6–12 m) or as cut-and-bend shapes fabricated to your bar-bending schedule. Mill Test Certificates (EN 10204 3.1), Certificate of Origin and CE documentation are available. Request a quote with your schedule or a simple list of bar marks and quantities.

Source German-standard rebar with full export documentation

Tell us your retaining wall specification and destination port — we’ll respond with a detailed quotation.

Request a Quote →