Whether you are building a small house or a large commercial building, foundation is crucial. They are what provide the support that your building needs to stand tall and sturdy. If the foundation of your building is not proper, it can become unsafe and unstable. There are two types of foundations, deep foundations and shallow foundations. Let’s look a little deeper into shallow foundations.
The best way to understand shallow foundations is to compare them with deep foundations.
As the name suggests, shallow foundations are placed near the surface. They do not go deeper than three meters deep into the ground. You can use shallow foundations for buildings with light loads and the soil close to the surface can bear it.
Deep foundations go deeper than that and are used if the soil cannot support your structure’s load. Engineers will also suggest deep foundations if your structure has to support hefty loads.
Now that the basic difference between deep foundations and shallow foundations is clear, we can go into the different types of shallow foundations. Each of these shallow foundations has its unique features and uses. It will be easier to choose the right foundation if you know the purpose of each type.
Spread Footing
Spread footing is one of the most common types of shallow foundations used in the construction industry. Often used in residential buildings, shallow foundations can ‘spread’ the load of the building over a large area. It can significantly reduce the pressure in the soil.
Strip Footing
The long and continuous strips of concrete that support walls in residential and commercial buildings are called strip footings.
Raft or Mat Foundation
When the soil has a comparatively lower bearing capacity, a large concrete slab is used to support the entire structure and distribute the load over the whole area. It is called the Raft Foundation.
Pad Footing
If the columns are spaced far apart, they will need individual support. In such cases, pad footings are used. They are isolated footings that can support these individual columns.
Combined Footing
Sometimes, columns are so close together that you cannot use traditional footings but they are not suitable for individual pad footings because they overlap, you can use combined footings. They can support two or more columns at the same time.
The ability of the soil in your site to support the loads your structure applies to the ground is called its bearing capacity. It is especially crucial to determine the bearing capacity of soil to understand what kind of shallow foundations should be used. Here are the factors that affect the bearing capacity
Soil Type: The type of soil available in your site gives it different strengths. Rock and gravel, for example, have more bearing capacity than clay or silt.
Moisture Content: The water in the soil reduces friction between soil particles, so the more the water content, the more slippery it becomes. As a result, wet soil will have a lower bearing capacity compared to dry soil.
Density: In dense soil, the soil particles are tightly packed together giving them a higher bearing capacity
There are several reasons why shallow foundations are popular in the industry. Here are some of them:
Since shallow foundations require less material and labor time, they are comparatively less expensive.
They are easier to construct.
If you know what type of soil you are working on, you have the option to customize your shallow foundation accordingly. They are flexible enough for experts to be able to design various shapes and sizes according to your building requirements and site conditions.
Since shallow foundations are constructed above 3 feet under the ground, they are easier to inspect and maintain.
Shallow foundations can be used in several different projects:
In cases where the building loads are comparatively lighter
In cases where the soil has enough bearing capacity
In cases where the construction is not intrusive
In structures like residential buildings, small commercial structures, and other buildings that are lightweight.
If you have a clear idea of shallow foundations, their advantages, types, which situations they are apt for, and what is the best steel for construction you can use for this, you can design the best shallow foundations apt for your specific needs.
