Last Updated on March 7, 2023 by Jose Villegas Jr.
Stepped footing is a footing with steps that are spaced around apart horizontally and vertically to achieve the appropriate width.
When it comes to constructing a building or any structure, the foundation is an essential part of the construction process. A stable foundation ensures the safety and longevity of the structure. Stepped footing is one of the popular types of foundations used in construction when some flat surface areas are not feasible. In this article, we will explore what stepped footing is, its advantages and disadvantages, and how it is constructed.
What is Stepped Footing?
Stepped footing is a type of foundation that is commonly used when the soil is not stable enough to support the load of the structure and has low bearing capacity. It is also used in areas where the soil is prone to movement or settling.
A step footer or stepped footing is constructed in levels or steps, each step being wider than the one above it. This type of foundation is designed to distribute the load of the structure over a larger area, thereby reducing the pressure on the soil.
Another purpose of stepped foundation is to prevent the column from direct contact with the ground underneath.
The stepped footing is also called a stepped foundation.
Stepped Foundation
Types of Stepped Foundation
There are two types of stepped foundations:
Simple Stepped Foundation
A simple stepped foundation is constructed by excavating the soil to the required depth and pouring concrete in layers, each layer being wider than the one above it. The number of steps depends on the load of the structure and the stability of the soil. Simple stepped footing is used for small to medium-sized buildings.
Stepped Raft Foundation
A stepped raft foundation is a variation of the simple stepped footing. In this type of footing, a concrete raft is constructed on top of the stepped foundation. The raft distributes the load of the structure evenly over the stepped foundation, providing additional stability.
Advantages of Stepped Footing
Stepped footing has several advantages, including:
Load Distribution
Stepped footing distributes the load of the structure over a larger area, reducing the pressure on the soil. This ensures the stability of the structure.
Cost-effective
Stepped footing is a cost-effective foundation as it requires less concrete and excavation than other types of foundations.
Easy to Construct
Stepped footing is relatively easy to construct, making it a popular choice for small to medium-sized structures.
Suitable for Unstable Soil
Stepped footing is ideal for areas with unstable soil or where the soil is prone to movement or settling.
Disadvantages of Stepped Footing
Stepped footing also has some disadvantages, including:
Limited Load Capacity
Stepped footing has a limited load capacity and is not suitable for large or heavy structures.
Uneven Settlement
If the steps are not constructed correctly, uneven settlement may occur, leading to structural damage.
Build the Stepped Foundation on the slope
The construction of stepped footing involves the following steps:
Step 1: Excavation
The soil is excavated to the required depth and width, and the soil is compacted to provide a stable base for the foundation.
Step 2: Rebar Placement
Reinforcing bars (rebar) are placed in the excavation to provide additional strength to the foundation.
Step 3: Pouring Concrete
Concrete is poured in layers, with each layer wider than the one above it. The concrete is allowed to cure before the next layer is poured.
Step 4: Stepped Raft Footing
If a stepped raft footing is required, a concrete raft is constructed on top of the stepped foundation.
House Foundation on Slope
The ground elevation is not always smooth and flat. During the construction of the house foundation on slope structures, there are some sites where the sloped surface of the ground is available. It is very difficult to construct a house foundation on a slope.
It is not possible to construct a house foundation on the slope by using a simple foundation.
Generally, the use of simple types of isolated footing in the construction of structures on level ground is implemented.
The construction of structures on the sloping site required filling material to uplift the level over the site to make it flat and smooth.
It is very expensive and time-consuming to level the surface by filling material and foundation walling on the sloping. The stepped footing is a widely used type of footing in the construction of house foundations on the slope.
During the construction of the foundation on the slope, it is very important that the right decision should be taken by proper planning whether the ground floor should be located at the highest level or at the ground level.
In the construction of the stepped footing, the width is constructed by the series of steps in the proportion of one unit of horizontal dimension to two units of the vertical direction. The foundation on the sloping sides can be constructed by cutting the portion of the foundation trench in a number of steps.
The step should not be more than the depth of the concrete bed and every step should be constructed at a different depth.
The lap of concrete at its top should not be less than the vertical thickness of the concrete.
Conclusion
Stepped footing is a cost-effective and easy-to-construct foundation that is ideal for small to medium-sized structures in areas with unstable soil. It distributes the load of the structure over a larger area, reducing the pressure on the soil and ensuring the stability of the structure. However, it has a limited load capacity and may lead to uneven settlement if not constructed correctly.
FAQs
1. Is stepped footing suitable for all types of structures?
No, the stepped footing is suitable for small to medium-sized structures only. It has a limited load capacity and is not suitable for large or heavy structures.
2. How is stepped concrete footing constructed?
Stepped footing is constructed by excavating the soil to the required depth and pouring concrete in layers as it appears like a set of stair steps, each layer being wider than the one above it. Reinforcement bars are placed in the excavation to provide additional strength to the foundation. If a stepped raft footing is required, a concrete raft is constructed on top of the stepped foundation.
3. What are the advantages of a stepped foundation?
Stepped footing has several advantages, including load distribution to layers of rock or soil with sufficient bearing capacity, cost-effectiveness, support for structures, ease of construction, and suitability for unstable soil.
4. What are the disadvantages of stepped footing?
Stepped footing has a limited load capacity and may lead to uneven settlement if not constructed correctly.
5. How can I ensure that I constructed it as per the stepped footing requirement?
To ensure that your stepped footing is constructed correctly, it is essential to hire a qualified and experienced contractor who has expertise in constructing stepped footings. It is also crucial to follow the proper construction procedures and use high-quality materials. Regular inspection and maintenance are also necessary to prevent any potential issues in the future.
tags: slope, stepped foundation wall, stepped foundations, shallow foundation, strip footing, pier, bearing stratum, beam, civil engineering, foundation depths, horizontal force vectors, step length