In the construction world, one of the essential parts of a building is the foundation, where all the other structures, such as columns or beams, are built. One common type of foundation is grade beams, which aim to spread the building’s weight and keep it stable, especially when the ground is loose or expands and contracts.
Grade beams, also called footing beams, are horizontal beams made of reinforced concrete that run the length or width of the base of a building. Instead of supporting individual walls or columns like traditional footings, grade beams span multiple supports, effectively connecting them and spreading loads equally.
This article lets us learn what grade beams are, their functions, advantages, and disadvantages.
Defining What A Grade Beam Is
As mentioned earlier, a grade beam, also known as a footing beam or perimeter beam foundation, is a rectangular-shaped concrete footing that runs under the house’s exterior walls. It is called that as it sits at the grade or ground level.
Grade beams use less concrete and can be put on natural soil with no frost or minimal frost. This is why it is ideal for many residential projects in areas that experience hot or humid weather. However, you might want to add insulation or dig a rubble trench below it to protect it from frost.
What Do Grade Beams Do?
A grade beam does the same as any other foundation. Grade beams’ main job is to evenly spread the weight of the building above them onto the foundation elements, like piles or piers. In this way, they help stop uneven settlement, which, over time, can damage buildings.
Figuring out the minimum width of the grade beam that will hold this load will depend on how much weight the dirt can hold. A grade beam’s main job is to move the weight from the bearing wall to the base or the ground and stop the building from sinking unevenly.
Let us compare grade beams with other common types of foundations.
The Difference Between A Base Beam and A Grade Beam
In a nutshell, a grade beam is built at the grade level, also known as the earth level, and the base beam is built at the base level. This way, it makes the pile caps stick together better.
The Difference Between A Wall Footing and A Grade Beam
The grade beam keeps the wall from bending and generally spans between the footing caps. On the other hand, a wall footing stands on soil and transfers the weight of the wall directly to the ground.
The Difference Between A Strap Footing and A Grade Beam
A grade beam moves the weight of the wall to the roots that support it, and a strap beam moves the weight of the column from one footing to another.
Advantages of Grade Beams
Usually, a footing and stem wall is the most common conventional foundation in northern areas since it allows you to have a basement or a crawl space. However, a grade beam is better than this type of foundation because the whole foundation is made at once instead of in several pours. A grade beam foundation is often chosen because it uses less concrete than other types of foundations. This means less money is spent on concrete and less energy is built into the building. A grade beam needs much less work and skill, saving time and making it easier for clients and builders.
In this section, let us look at the advantages of using grade beams for your next project.
Stability in Poor Soil Conditions
If the soil on a building site is weak or unstable, grade beams can help support the structure by spreading its weight over a larger area. This lowers the risk of settlement or foundation failure. Grade beams can help hold the base in place and stop it from moving when the ground moves.
Handle Heavy Loads or Lateral Forces
Grade beams can help strengthen the foundation of a building when heavy loads or lateral forces like wind or earthquakes are a worry. This can make the structure more stable and robust.
Construction of Bridges
Grade beams are often used to hold the abutments and spread the weight of the bridge deck across the ground below.
Resistance to Damages
One of the best things about grade beams is that they can stop dirt from moving. They can handle side forces and help keep the base from damage by soil that expands or contracts.
Design Flexibility
Grade beams come in many sizes and types for various building tasks. They are flexible enough to be changed to fit special load-bearing needs. Because grade beams are bendable, they can be built in any shape or size.
Value for Money
Grade beams are often cheaper than complicated support systems. They need less digging and materials, lowering the total building cost. When grade beams are built, they need less digging and less concrete. Because the grade beam is easy to make, it takes less time and labor, which is good for the business. It costs less to use a grade beam footing than a regular foundation.
Disadvantages of Grade Beams
Now that we have discussed the advantages of a grade beam, let us move on to the disadvantages.
No Space For Basements
If you want a basement, grade beam supports do not work for this space since they are rectangular footings that run throughout the exterior of the home.
Soil Conditions
Another reason is that grade beam supports need a level place to build. If you are building on a hill, you must do a lot of work on the ground before starting a grade beam foundation. You may choose a different type of foundation that can handle slopes. It is unsuitable for places with many slopes or hills because it needs much digging to build.
The conditions of the soil have a significant impact on how well grade beams work. You may need more base support in places with unstable or expansive ground.
Limited Capacity to Hold Weight
One big problem with grade beams is that they can only hold so much weight. They might not work for cumbersome structures or many floors.
Allowance for Moisture
Grade beams can allow moisture to get in, which can cause them to crack or break down over time. To solve this problem, proper protection is needed.
Maintenance Needs
To ensure grade beams stay strong over time, they must be inspected and fixed regularly. Not doing upkeep can lead to repairs that cost a lot of money.
How Do You Build A Grade Beam?
In construction and civil engineering, the grade beam is an essential structural part that determines how stable and able to support the weight of a building. Whether you are a seasoned builder or just a curious homeowner, it is critical to have a good understanding of each part of the project.
Let us look at the steps to building a grade beam.
Level The Building Area
The first step to building grade beams is to level the building area. A grade beam needs a flat surface in order for it to work, so it is critical to be able to evaluate site conditions and do the appropriate work.
Put The Concrete Stripping Forms Down
After digging a trench and preparing the site, the formwork is put in place according to the measurements shown on the plan.
You can use already-made forms, create your own out of wood, or use foam board to make your own. The second option makes excellent sense if you already use foam to insulate the base. With foam, you don’t have to take the forms off first, which is a big plus. You will need to build a rubble trench footing and insulate to protect against frost if you are building in an area with mild to deep frost depths.
Placement of Reinforcement
Once the forms are finished, the beam support can be put in place. The structural plan should be used to guide where the bars go.
In structural drawings, you can see more information about bars, like their diameter and the number of longitudinal reinforcements they have. You can also see the width and spacing of the stirrup bars.
Pouring of Concrete
The grade beam can be made with either ready-mixed or mixed concrete on-site at a machine. When there is a lot of concrete, RMC is better.
If ready-mixed concrete is used for casting, the concrete provider only needs to know how strong the concrete is. When making machine-mixed concrete, you should choose the right amount of concrete ingredients to get the strength you want.
After filling the concrete, it should be appropriately packed down with a vibrator, and the top should be finished.
Removal of Formworks
The beam’s sides can be removed after 24 hours of making concrete, but the bottom shouldn’t be removed until the concrete is strong enough. How long it takes to take off the bottom form depends on how long the clear span is.
Key Takeaway
In conclusion, grade beams are essential to many building projects because they make the structure more stable, stop soil from moving, allow for more design options, and save money. But they also have some disadvantages, like being unable to hold much weight, being easily damaged by water, being sensitive to changes in the soil, and needing maintenance. It is essential to carefully examine the site’s factors and structural needs to decide if grade beams are the best choice for a specific project.
However, grade beams might not be needed or suitable for every building job. When deciding if grade beams are required, things like the type of soil, the building’s plan, the budget, and the building codes in the area should all be considered.