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What Are The Most Common Footings in Residential Construction (7 types)

introduction

This article will explain what concrete footings are, what the different types of footings are, and when and why they are used in specific situations in residential construction. There are visual aids to show what each type of footing looks like within the respective sections to help you understand the descriptions. Our goal here at Four Oaks Residential, is to educate our viewers about construction trades and their processes here in the United States.

WHAT ARE FOOTINGS?

A footing is an excavated trench filled with concrete that is a specific width and depth. A footing is a three part construction project: the layout, excavation and concrete pour. There are footings for concrete foundations, masonry foundations, retaining walls, and columns. If you want to learn more about how footings are constructed, visit our “how-to” for footing construction.

THE PURPOSE OF CONCRETE FOOTINGS

Concrete footings are an integral part of almost every construction project, whether it’s residential, commercial, or industrial. Here’s why.

 

The footing is what supports every foundation, no matter the type. You know what sits on top of your foundation? Everything. The floor framing, the walls, the roof, and all of the contents on the interior. Think refrigerators, washer and dryer, bathtubs, fish tanks, stereo equipment, heavy cabinets and furniture, large couches, and all of the homeowner’s personal belongings as well.

 

The footing is what keeps your building from literally sinking into the ground over time. This is why it is so important to dig and install the footing properly.

WHAT IS THE MOST COMMON TYPE OF FOOTING?

You are probably here because you searched: “What is the most common type of footing in residential construction?” into your Google search. With that in mind, I’m just going to answer your question upfront and let you decide if you need to read further down 🙂. The most common types of footing in residential construction are Isolated and Continuous spread footings. They are both part of a shallow foundation construction hence why they are used in residential construction. In addition, the other five footing types are Raft, Strap, Strip, Pile, and Combined footings. Let’s start with the two most common footings first.

1. Isolated Pier Footings

An isolated pier footing is an individual concrete footing that is intended to carry heavy loads at one specific point, such as with an individual column. Isolated footings are typically referred to as “pier” footings.

footing construction isolated pier footing drawing

In residential construction, there are block support columns (piers) built on the interior of the foundation walls in specified areas, usually in a row. These will be your interior supports for your wooden floor system. An example size for a footing would be something like 30”W x 30”L x 8”D for a 16”x16” masonry pier.

Pier footings are required for crawl space foundation construction, no matter whether you are building a custom home, a modular home, or even while placing a mobile home. Check out Four Oaks Residential’s footing page to see real life project photos.

2. Continuous Spread Footing

An isolated pier footing is an individual concrete footing that is intended to carry heavy loads at one specific point, such as with an individual column. Isolated footings are typically referred to as “pier” footings.

footing construction continuous spread footing drawing

A continuous footing can be simply defined as a footing that runs continuous and does not have any spaces or gaps. It has a beginning and an end and the two touch. In residential construction, we call this a perimeter footing because it extends around the entire perimeter of the home. The outer foundation walls are built on this footing. Continuous spread footings are designed to carry heavy loads. Check out some examples of full masonry walls built on continuous spread footings here.

If you were to look at a set of blueprints on the foundation page, you would see the walls marked in thick black lines and you would notice dashed lines that represent the footing. A typical residential continuous perimeter footing would measure 16” in width, at a  depth of 8” by XX number of feet. Note that this is for a 1-story home in my location (in the eastern United States). In colder climates, the frost line is much deeper and requires a different footing thickness or a different type of footing altogether.

WHAT ARE THE OTHER TYPES OF FOOTINGS?

The remaining 5 types of footings are used for residential, commercial, and industrial building projects. While you can use most of these for residential projects, they are more commonly used in larger builds. The other types of footings are raft, strap, strip, pile, and combined footings.

3. Raft (Mat) Footings

When there are many tightly spaced columns in a foundation layout, a raft or mat footing may be needed. Typically, contractors would use a continuous spread footing or an isolated footing for columns. Imagine if you had to build 20 masonry piers inside of a 26’x16’ area. Remember, the footings are wider than the piers so there is even less spacing to dig the proper sized footings. It would be much easier to create one large rectangular footing and pour the concrete all at once in one spot. This is a raft footing.

footing construction raft footing drawing

Raft footings are typically used in the construction of larger, multi-story buildings, but they can also be used in the construction of single-family homes. They are a popular choice for residential because they provide a strong and stable foundation that is resistant to movement and settlement, which helps to ensure the long-term stability and integrity of the building. There are some great examples of practical real world applications here on TheConstructor.org.

4. Strap Footings

A strap footing is used when there are columns separated by a large distance that need a “brace” between them to keep them properly supported. Each column will have its own footing for support just like normal. There is a trapezoidal piece of footing that is poured connecting the two columns to offer additional support.

footing construction strap footing drawing

Strap footings are efficient and save a ton of time and materials, when these extended footings are required. Look at the diagram above to better understand how this is built in the real world.

5. Strip Footings

Strip footings, also commonly known as “strip foundations” are actually a type of foundation that is very similar to a continuous spread footing. Strip footings are designed for structures that have lower load requirements, like with one story homes or other low-rise buildings.

footing construction strip footing drawing

These footings are used to support walls and columns and are also excavated and poured below the frost line to prevent cracking or failure in freezing temperatures. Some strip footings are reinforced with steel rebar to increase their overall strength and durability over time. The main difference between a continuous spread footing and a strip footing is the size and load-bearing capacity. Continuous spread footings are typically larger and used for multi-story homes and higher load-bearing structures.

6. Pile Footings

A type of deep foundation that is used to support the load of a structure and distribute its weight evenly across the ground. A pile footing consists of a series of vertical or angled piles that are driven into the ground to support the load of the structure being built. Typically used for high-rise buildings with very heavy loads, structures built on unstable soils, and flood prone areas.

footing construction pile footing drawing

Pile footings are usually made from concrete and steel, but sometimes wood is used also. As you might expect, pile footings are most commonly used in commercial and industrial construction and hardly ever used in residential construction. It is time consuming, material heavy, and difficult to install compared to other types of foundations.

7. Combined Footings

A combined footing is a combination of two different types of footings used together to create the ultimate support for a building with very heavy load requirements. Usually, combined footings are used when columns are too close for individual footings and also when columns are too far apart for individual footings.

footing construction combined footing drawing

The solution for columns too close, is to create a footing that encapsulates the two columns and necessary space around. The solution for columns too far away from each other, is to create individual footings for both and add another style of footing to connect the two footings. Combined footings are used on an “as-needed” basis to help distribute loads evenly on a foundation that has odd spacing or covers great distances.

IN CONCLUSION...

In this article, we have reviewed 7 most common footings used in residential construction. Isolated, Continuous Spread, Raft, Strap, Strip, Pile, and Combined footings were defined and included a short description on how they are used in construction.

Some things to consider when choosing the proper footing for a residential build include the size and type of structure, the quality (load-bearing capacity) of your soil, the local climate, and the local building code requirements. It is very important to consult with a structural engineer to make sure that you choose the right footing for your next build. If you are interested, you can check out some of the building codes for almost anywhere at the International Code Council.

We learned that it is extremely important to choose the right footing for your home or building project, because the footing is the foundation of the entire building. It is responsible for supporting the load of the entire building and distributing it evenly. In addition to supporting the loads evenly, a footing is crucial for the stability and safety of the building for its life.

If you just happen to be in North Carolina and need a team of professionals for footing and foundation work, you should hire us! Four Oaks Residential has over 3,000 footing and foundation projects completed and we’ve been in business for over 25 years. Drop us a line: Contact Four Oaks Residential

“Construction is the art of making a meaningful whole out of many parts. Buildings are witnesses to the human ability to construct concrete things.”

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We are construction junkies and love educating people on the conventions and trends in the residential construction space. We use our blog to post informational articles, how-to’s and sometimes show off our own construction projects. We love the transparency and it really does give non-construction folks a view into the industry.

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