Table of Contents
Quick Summary
- Eccentric footing is used when a column is located close to a property boundary, leaving insufficient space for a symmetrical footing.
- In this type of footing, the column and footing centres do not align, causing uneven soil pressure beneath the foundation.
- The article explains the differences between eccentric, concentric, and combined footings, including where each type is typically used.
- Eccentricity (e) creates a bending moment that must be considered during footing design.
- The footing should generally keep the eccentricity within the kern (L/6) to maintain soil contact.
- The article also covers uniaxial and biaxial eccentricity, common problems from poor design, and important checks for soil pressure and reinforcement.
- Proper design should consider soil bearing capacity, column loads, footing dimensions, bending moments, and reinforcement, with the final design confirmed by a qualified structural engineer.
Courtesy - Magnific(Image 1, 2)
Have you ever seen a house built right up to the edge of a plot, with barely any gap to the neighbour’s boundary wall? Ever wondered how the foundation manages to support the column when there’s no room to spread the footing evenly on both sides? That’s exactly the problem eccentric footing solves.
An eccentric footing is a type of foundation where the centre of the column and the load it carries do not align with the centre of the footing beneath it. Normally, a footing is built symmetrically around a column, so the load lands right in the middle and spreads evenly into the soil. But when a column sits close to a property boundary, and there’s simply no space to extend the footing outward on that side, engineers shift the footing so it fits within the available plot area. The column then ends up off-centre on the footing, and that’s what makes it “eccentric.”
Because the load is no longer centred, there is an uneven distribution of soil pressure—one edge takes more pressure than the other. This guide breaks down what that means, why it happens, and what to watch out for, in plain language.
What Is Eccentric Footing?
In simple terms, eccentric footing is a footing where the column’s centre and the footing’s centre don’t match up. In a normal, or “concentric,” footing, the load and the footing centre are perfectly aligned, so the pressure on the soil below is even all around. In an eccentric footing, that alignment is broken – the column sits closer to one edge than the other.
This shape is often called a shoe footing, because the outline of the footing—extended on one side and cut short on the other resembles the sole of a shoe.
Why Is Eccentric Footing Used? (The Property Line Problem)
The main reason eccentric footing exists is simple: the column sits next to a property boundary or setback line, and the footing can’t extend past the column on that side without encroaching on the neighbour’s land.
It’s also used when a column is very close to an existing building or a shared party wall, where digging out a symmetric footing isn’t physically possible.
You’ll most commonly see eccentric footings at the corners of a plot, where two sides are boundary-constrained at the same time. In these cases, the footing is extended only on the inward side, which is exactly why it earns the nickname “shoe footing.”
Eccentric Footing vs Concentric Footing
The easiest way to picture the difference is this: a concentric footing is like standing flat-footed, with your weight spread evenly across both feet. An eccentric footing is like standing on your toes on one side – the pressure isn’t even anymore, and something has to account for that imbalance.
In a concentric footing, the load lands at the centre, so the soil pressure below is even. In an eccentric footing, the load lands off-centre, so the soil pressure becomes uneven – heavier on one edge, lighter on the other. That’s the practical reason eccentric footings need an extra design check for bending, a twisting effect that a concentric footing simply doesn’t have to deal with.
Eccentric Footing vs Combined Footing – Which One Do You Need?
When a column sits on a boundary, engineers usually choose between two solutions: an eccentric footing or a combined footing.
A combined footing joins the boundary column’s footing to the next column’s footing using a connecting beam, often called a strap. That strap beam helps balance out the tipping effect caused by the off-centre load. An eccentric footing, on the other hand, doesn’t use a strap – it’s simply a reshaped footing that fits within the available space.
As a general rule of thumb: if the soil’s bearing capacity is good and the gap between columns is reasonably wide, an eccentric footing tends to be the more economical choice. If the soil is weaker, or the columns are close together, a combined footing is typically the safer and more common option.
That said, this decision should always be confirmed by a structural engineer for your specific site—soil test reports and actual column loads vary from project to project, and this isn’t a call to make on assumptions alone.
What Is “Eccentricity” (e) in Footing Design?
“Eccentricity,” written as e, is simply the distance between the centre of the load and the centre of the footing base. The bigger this distance, the bigger the tipping or bending effect on the footing.
In engineering terms, this off-centre load creates what’s called a bending moment – think of it as a twisting force trying to tip the footing over, in addition to the straightforward downward load it already carries. Both effects have to be accounted for when the footing and its reinforcement are designed, which is why eccentric footings need more careful engineering than a standard centred footing.
What Is the “Kern” of a Footing? (Why There’s a Safe Limit)
Here’s where the design gets interesting. Engineers use a concept called the kern – think of it as a “safe zone” in the middle of the footing. As long as the load stays inside this zone, the entire footing stays pressed firmly into the soil, with no lifting at the edges.
For a rectangular footing, this safe zone works out to about one-sixth of the footing’s length (L/6), measured from the centre. As long as the eccentricity (e) is less than L/6, the footing is considered safe, and the soil pressure below it varies smoothly – heavier on one edge, lighter on the other, but never dropping to zero. Engineers call this a trapezoidal pressure distribution.
If the eccentricity reaches exactly L/6, the pressure at one edge drops all the way to zero – the footing is sitting right at the boundary of the safe zone, and the pressure distribution becomes triangular instead of trapezoidal.
If the eccentricity goes beyond L/6, part of the footing actually lifts off the soil. That portion of the footing stops doing any useful work, the pressure on the remaining contact area increases sharply, and the footing typically needs to be redesigned – either made larger, repositioned, or replaced with a different footing type altogether.
Uniaxial vs Biaxial Eccentric Footing
Eccentricity doesn’t always occur in just one direction.
A uniaxial eccentric footing has its load off-centre along just one direction – say, along the length of the footing, but centred along its width. A biaxial eccentric footing has its load off-centre along both directions at once.
Biaxial eccentricity typically shows up at corner plots, where a column is constrained by boundaries on two adjoining sides at the same time, forcing the footing to shift inward on both axes.
What Goes Wrong with Poorly Designed Eccentric Footing?
Because eccentric footings are already carrying an uneven load, mistakes in their design tend to show up as real, visible problems in the finished building:
- Tilting of the column or structure over time, if the pressure imbalance isn’t properly accounted for.
- Differential settlement, where one side of the footing sinks more than the other – this is often what causes diagonal cracks in walls or uneven floors above.
- Soil overstress at the heavily loaded edge, where the pressure on the soil exceeds what it can safely bear, even if the average pressure across the footing looks fine on paper.
This is exactly why eccentric footings need more careful checking than a standard footing – the risk isn’t spread evenly, it’s concentrated at one edge.
Key Design Checklist for Eccentric Footing
If you’re a homeowner discussing this with your engineer, or just want to understand what should be happening behind the scenes, here’s what a properly designed eccentric footing accounts for:
- Soil bearing capacity checked at both edges of the footing – the maximum and minimum pressure, not just the average.
- Reinforcement sized for both the axial load and the bending moment, not just a standard evenly-loaded footing.
- Confirmation from a qualified structural engineer on the eccentricity, kern position, and reinforcement for your specific site – this is not something to estimate on your own.
Eccentric Footing vs Other Footing Types (Quick Comparison)
| Feature | Concentric Footing | Eccentric Footing | Combined Footing |
| Load alignment with footing centre | Aligned | Not aligned | Not aligned, but balanced via strap beam |
| Soil pressure distribution | Uniform | Uneven (trapezoidal or triangular) | Balanced by connecting beam |
| Typical use case | Standard columns away from boundaries | Columns on or near a property boundary | Columns close together, or near a boundary with lower soil bearing capacity |
| Cost/complexity | Simplest | Simple, but needs a bending moment check | More complex – the strap beam adds cost |
| Reinforcement requirement | For axial load only | For axial load plus bending moment | For axial load plus moment, shared across both footings |
| Best suited soil condition | Any adequate soil | Good bearing capacity, wider column spacing | Weaker soil, or narrow column spacing |
Eccentric Footing FAQs
1. Is eccentric footing the same as shoe footing?
Yes – “shoe footing” is simply the common nickname for an eccentric footing, based on its L-shaped or shoe-like outline. Both terms describe the same structural concept: a footing extended on one side to keep the column load within the footing area while staying clear of the property boundary.
2. Can eccentric footing be used for all boundary-line constructions, or only in specific soil conditions?
It depends on the soil’s bearing capacity and the size of the load being carried. Eccentric footing works well when the soil can safely handle the uneven pressure distribution it creates. In weaker soil, or where loads are heavy, a combined or strap footing is often used instead, since it spreads the load more evenly between two footings.
3. How do you calculate eccentricity (e) for a given footing?
Eccentricity is the distance between the centre of the column load and the centre of the footing base. In practice, this is calculated by a structural engineer as part of the footing design, using the column’s position relative to the boundary and the footing dimensions – it isn’t something to estimate without proper structural calculations.
4. What is the maximum allowable eccentricity before redesign is needed?
As a general rule, the eccentricity should stay within the “kern” of the footing – for a rectangular footing, that’s roughly one-sixth of its length (L/6). Beyond this point, part of the footing loses contact with the soil, and the design needs to be revised, typically by resizing or repositioning the footing.
5. Does eccentric footing cost more than a standard isolated footing?
It can cost slightly more than a standard isolated footing, mainly because of the extra reinforcement needed to handle the bending moment. However, it’s usually more economical than a combined or strap footing, since it avoids the cost of the connecting beam – making it a practical middle-ground solution for boundary columns on reasonably good soil.
Author & Expert Review
Written By: 
Nidhi Patel | Civil Engineer & Content Writer
| Credentials: B.E. (Mahatma Gandhi Institute of Technical Education and Research Centre), Registered with Gujarat Technological University (GTU). Experience: Civil Engineer with 3+ years of content writing experience, currently writing blogs for Gharpedia, part of SDCPL. Expertise: Specializing in SEO-optimized blogs and long-form articles focused on home improvement, construction, interiors and architect topics. I create well-researched, reader-focused content that balances technical accuracy with clarity, making complex subjects easy to understand. Find her on: LinkedIn |
Verified By Expert: 
Ravin Desai – Co Founder – Gharpedia | Co Founder – 1 MNT | Director – SDCPL
This article has been reviewed for technical accuracy by Ravin Desai, Co-Founder of Gharpedia and Director at Sthapati Designers & Consultants Pvt. Ltd. With a B.Tech. in Civil Engineering from VNIT Nagpur and an M.S. in Civil Engineering from Clemson University, USA, and over a decade of international and Indian experience in the construction and design consultancy sector, he ensures all technical content aligns with industry standards and best practices.
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