👋 Introduction

A pad footing must be checked against overturning to ensure its stability:

Overturning forces: Horizontal forces and applied moments tend to rotate the footing about its toe (the edge of the footing base).
Resisting forces: The vertical load from the structure and the footing’s own weight help resist overturning by providing a stabilising moment.

Below work example runs the overturning check of a 3.0 m × 3.0 m pad footing, 0.5 m deep, carrying a horizontal force F_y = 50 + 10 kN, an applied moment M_y = 50 + 50 kNm and a vertical force F_x = 20 + 5 kN, in the same order a calculation report runs it:

Self weight — the weight that creates the restoring moment
Restoring moment — the vertical forces about the toe
Overturning moment — the applied moment and the horizontal force
Overturning check — restoring against overturning, with the required factor of safety

The concept behind each step is explained in the companion article: Pad Footing Stability Check: Sliding, Overturning and Bearing Capacity - A Simple Guide.

📐 Design Data

Below is the design information of the pad footing, which we will check under the horizontal force and the applied moment.

Pad Footing
	Type	Pad footing (concrete)
	Length, L	3.0 m
	Width, W	3.0 m
	Depth, D	0.5 m

Design Loads
Vertical Force, F_x (Dead / Live)		20 kN / 5 kN
Horizontal Force, F_y (Dead / Live)		50 kN / 10 kN
Applied Moment, M_y (Dead / Live)		50 kNm / 50 kNm

Safety Factor
Factor of Safety, Overturning		1.5

Load Combination (SLS)
Dead Load Factor, f_DL		1.0
Live Load Factor, f_LL		1.0

🔢 Calculation Steps

*The check below follows the code-neutral factor-of-safety practice of the stability check guide.

1.Footing Self Weight

Footing Volume(Geometry)
$V$	=	$L \times W \times D$
	=	$3.0 \times 3.0 \times 0.5$
	=	$\text{4.5 m}^3$

Footing Self Weight(Concrete density ρ = 25 kN/m³)
$SW$	=	$V \times \rho$
	=	$4.5 \times 25$
	=	$\text{112.5 kN}$

2.Restoring Moment about the Toe

Vertical Force (service)(SLS load combination)
$F_{x,SLS}$	=	$F_{x,DL} \times f_{DL} + F_{x,LL} \times f_{LL}$
	=	$1.0 \times 20 + 1.0 \times 5$
	=	$\text{25 kN}$

Resistance Moment about the Toe(Restoring moment)
$M_{resis}$	=	$(SW \times f_{DL} + F_{x,SLS}) \times \frac{L}{2}$
	=	$(112.5 \times 1.0 + 25) \times 1.5$
	=	$\text{206 kNm}$

Both vertical forces act at the centre of the base, so their lever arm about the toe is W/2 = 1.5 m.

3.Overturning Moment about the Toe

Horizontal Force (service)(SLS load combination)
$F_{y,SLS}$	=	$F_{y,DL} \times f_{DL} + F_{y,LL} \times f_{LL}$
	=	$1.0 \times 50 + 1.0 \times 10$
	=	$\text{60 kN}$

Applied Moment (service)(SLS load combination)
$M_{y,SLS}$	=	$M_{y,DL} \times f_{DL} + M_{y,LL} \times f_{LL}$
	=	$1.0 \times 50 + 1.0 \times 50$
	=	$\text{100 kNm}$

Overturning Moment about the Toe(Overturning moment)
$M_{over}$	=	$M_{y,SLS} + F_{y,SLS} \times D$
	=	$100 + 60 \times 0.5$
	=	$\text{130 kNm}$

4.Overturning Check

Overturning Check(Factor of safety)
$\frac{M_{resis}}{M_{over}}$	=	$\frac{M_{resis}}{M_{over}} \ge 1.5$
	=	$\frac{206}{130}$
	=	$1.59 \ge 1.5,\ \text{OK!}$

∴ The section is sufficient for Overturning.

The factor of safety is 1.59 against 1.5 — about 95% utilisation, so the check just passes. The 130 kNm overturning moment is dominated by the applied moment (100 kNm); the horizontal force adds only 60 × 0.5 = 30 kNm because it acts low, at the top of a shallow footing.

🙋 Frequently asked questions

1. What is the overturning check of a pad footing?

It confirms that the restoring moment of the vertical forces about the toe beats the overturning moment of the horizontal force and any applied moment, with a required factor of safety — here 206 kNm against 130 kNm, a factor of 1.59 against 1.5.

2. Why are the moments taken about the toe?

Because the toe — the leading edge of the base (point A in the figure) — is the edge the footing would rotate about if it tipped. Taking moments about any other point would mix in forces that do not actually resist the rotation.

3. Why are service (unfactored) loads used?

Like the sliding check, overturning is a stability check that many design codes evaluate at the service level with a factor of safety on the result — the SLS combination (f = 1.0) is used here, as in the source calculation. Check which combination your design code requires.

4. What can I do if the overturning check fails?

Widen the base — it increases the lever arm W/2 and the self weight together. Adding weight on the footing also helps. Note that deepening the footing is less effective for overturning, because the horizontal force acts at the top — a deeper footing raises that force's lever arm as well.

5. What is the difference between overturning and sliding?

Overturning is a rotation about the toe — a moment check. Sliding is a rigid sideways movement — a force check. A footing that passes one can still fail the other; the sliding work example shows the force check, and the stability check guide runs all three checks together.

📄 Need a Pad Footing Overturning Check in Your Design Report?

If you want a ready-to-submit design report with the overturning check and the full stability checks of your pad footing, feel free to try our application — what you need is just the design data values, and a ready-to-submit PDF report will be generated in a minute.

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#foundation design #work example #geotechnical

CivilSimple Team

The CivilSimple Team writes practical engineering guides for the profession and the curious. All articles are reviewed for technical accuracy before publication.