Explaining a Concrete Footing
When it comes to building a home, it’s easy for homeowners to confuse footings and foundations. Footings help the foundation do its work. Without these structures, the foundation won’t be as stable or sturdy as needed to support the entire house.
What Are Footings?
Concrete footings support the foundation and stop it from settling.
When building the concrete footing, the bottom of the trench must be level, while its sides must be straight. The dimension of any footing depends on the type and size of the structure. When properly placed, footings can provide adequate support to the foundation and therefore, the entire house.
These types of footings are different designs used in construction to provide support and stability for load-bearing walls and structures:
- Spread footing: Has a broader base that spreads the structure’s weight over a larger area than the load-bearing wall that it supports.
- Stepped footing: Isolated footing that transfers the load from unstable to stable soils..
- Trench footing: Made from reinforced poured concrete, trench footing is the gold standard in foundation construction.
Footings are also suitable for other structures, including decks, retaining walls, and pergolas. Building contractors also recommend footings in areas with expansive or shifting soils, which will likely cause foundation settlement and other damage.
How to Build Concrete Footings
- The soil is first dug up.
- Next, wooden formwork is set up.
- Concrete is mixed on a clean surface.
- Concrete is poured right into the formwork.
- Refill material or soil is brought to the site.
- The home’s foundation is compacted, and
- The concrete cures within a couple of days or weeks.
Factors That Impact Footing Construction
When it comes to constructing footings, there is much more to the process than simply digging a hole and pouring concrete. In addition to ensuring that the footing is level and properly aligned, engineers and builders must also consider several outside factors, including soil type, building load, moisture content, and climate. These factors can impact the size, depth, and reinforcement needed for the footing, as well as the overall structural integrity of the building. Let’s look closely at some key factors that can impact footing construction.
Soil Type
Soil varies in type across the country and the world, but all contain the same three ingredients: clay, silt, and sand. Denser soils are preferable for construction as they respond better to the structure’s weight. Concrete footings will rest on three types of soil: man-moved, backfill, and native soil layers.
A structural engineer must be involved to properly construct a footing, assessing and inspecting the soil to determine the best solution. They may recommend replacing the soil or adding materials to improve its load-bearing capacity.
Building Load
The weight of the structure being built is a significant factor in determining the size and reinforcement required for the concrete footing. The size, design, and materials used in construction will also impact the load capacity of the footing. Heavier structures will require larger and more heavily reinforced footings to distribute the load, while lighter structures may only need a minimal footing.
Moisture Content
Soil moisture is a critical factor for building contractors to consider, as it affects the density of concrete footings. If concrete is poured into dry soil, the soil will absorb water from the concrete, resulting in weaker concrete. To prevent this, dry soil should be dampened before pouring concrete. However, not all dry soils require the same amount of moisture, as different soils have varying drainage properties. Sandy soils drain well, silty soils have intermediate drainage, and clay soils expand and shrink when wet and dry, respectively. Excess moisture increases the water-to-cement ratio, weakening the footing.
Climate
Environmental factors, such as freeze-thaw cycles, high winds, and seismic activity, can impact the design and construction of the footing. These factors can affect the soil conditions, causing soil shifting and erosion, compromising the footing’s stability. Proper design and reinforcement must consider the expected environmental loads to ensure the footing’s longevity and stability over time.
The Pros and Cons of Concrete Footings
Concrete footings have numerous advantages, but the main ones that are also the function of this structure are to support and anchor the foundation, preventing the house from settling. Concrete footings are your first line of defense that need to withstand environmental loads and natural forces.
However, the underlying soil and local weather can significantly damage the footing, foundation, and your home. Soil that is too wet, too dry, or was not properly prepared during construction can shift. This shift can compromise your footings and leave the rest of the structure without the vital support it needs, resulting in various signs of damage. Concrete also can succumb to damage over time, even though it is a durable material.
How Professionals Repair Damaged Footings and Foundations
Different kinds of foundation damage are common; some may point to problems with the concrete footing. The only way to know for sure is to have a free foundation inspection completed by an expert from your local Groundworks company. They will thoroughly evaluate your home, accurately diagnose your foundation problems and their causes, and then recommend solutions tailored to meet your home’s unique repair needs.
The footing is also critical during one of our repair processes. When we repair foundation settlement by installing pier systems like helical piers or push piers, we dig down far enough to access the bottom of the footing, drive the piers down to more stable, load-bearing soil, and attach heavy-duty brackets to the footing. This further enhances the piers’ capacity and the stability your foundation and home rely on.
For more information about concrete footings or how you can protect your foundation, contact Groundworks today to book a free inspection and estimate for the best fixes for your foundation.
FAQs
The three most common types of foundations found across the country are basement, crawl space, and slab. While each one is constructed a bit differently, they all have a concrete footing to help give them a solid base. Even a crawl space, which typically has a dirt floor, is constructed by first pouring a footing and then adding foundation walls on top of it. There are other ways of constructing homes, however, including pier and beam foundations that are common in Texas. These foundations are similar to crawl spaces but are not enclosed.
While many footings are approximately one foot deep, the footing depth greatly depends on other building specifics like the number of stories and the strength and capacity of the soil. Engineers and builders also must consider factors such as the frost line, soil type, and water table in the area where the home is to be built.
As with footing depth, the weight a footing can support is dependent on many variables. These include how tall the home will be, what type of house it is, the materials used for construction and aesthetics, and the type of soil at the build site and its condition and load-bearing capacity. Builders will also consider the weight of people, furniture, and other contents.