All About size steel beam for 20 feet span

All About size steel beam for 20 feet span

Choosing the right size steel beam is crucial when it comes to building structures that can withstand heavy loads over a wide span. In order to maintain proper support and stability, it is essential to have a clear understanding of the different sizes and types of steel beams available. In this article, we will delve into all the essential information you need to know about selecting the appropriate steel beam size for a 20 feet span. From discussing the basic principles of beam sizing to exploring the different factors that can affect the choice of size, this article aims to provide a comprehensive guide to help you make an informed decision for your construction projects.

What size steel beam for 20 feet span

What size steel beam for 20 feet span

When designing a steel beam for a 20 feet span, there are several factors to consider that will determine the appropriate size for structural support. These factors include the type of structure, the load it will bear, and the code requirements set by the local building department.

Firstly, it is important to determine the type of structure that the steel beam will support. Is it a residential or commercial building? Is it a single-story or multi-story structure? This information will help in selecting the appropriate design for the beam.

Secondly, the load-bearing capacity of the beam must be taken into consideration. This refers to the maximum weight that the beam can safely support without buckling or failing. The live load, which is the weight from people and furniture, and the dead load, which consists of the weight of the structure itself and any permanent fixtures, must be calculated and factored into the design.

Lastly, the local building codes must be adhered to when determining the size of the steel beam. These codes will provide the minimum requirements for beam size and design based on the type of structure and the expected load.

In general, a 20 feet span would require a steel beam that has a depth of at least 12 inches. The beam will also need to have a minimum thickness or web width of 6 inches and flange width of 4 inches. However, this is a general guideline and it is best to have a structural engineer or architect calculate the exact size and specifications based on the specific project requirements.

Additionally, the type of steel used for the beam will also impact its size and load-bearing capacity. Common types of steel used for beams include structural steel, which is characterized by a W-shaped cross-section, and I-shaped beams, known as I-beams. I-beams are typically more efficient and can carry a higher load compared to W-beams.

In conclusion, the size of the steel beam for a 20 feet span will depend on several factors such as the type of structure, load-bearing capacity, and local building codes. It is important to consult with a structural engineer or architect to ensure the correct size and specifications are used for the safe and efficient design of the steel beam.

What size steel beam or RSJ for 20 feet span

What size steel beam or RSJ for 20 feet span

When it comes to constructing any structure, selecting the right size of steel beam or RSJ (Rolled Steel Joist) is crucial for ensuring its strength and stability. This is especially important when spanning a distance as long as 20 feet, which requires a significant amount of load-bearing capacity.

Before determining the size of the steel beam or RSJ needed for a 20 feet span, it’s important to first understand the factors that influence this selection. These include the type of load the beam will be supporting, the type of structure it will be incorporated into, and the desired level of deflection (bending) or vibration in the beam.

As a general rule, the larger the span, the larger the size of the beam needed. For a 20 feet span, the beam will be subject to a significant amount of load, which means it should be designed to resist this load and maintain its shape without significant deflection or vibration.

The most common type of steel beam or RSJ used for a 20 feet span is an I-beam or Universal Beam (UB), also known as a parallel flange beam. This type of beam consists of two horizontal flanges connected by a vertical web, forming a shape similar to the letter “I.” I-beams are known for their high strength-to-weight ratio, making them ideal for long spans.

The size of an I-beam is determined by its depth (the distance from the top to the bottom flange) and weight per linear foot (plf). For a 20 feet span, a 10-inch deep I-beam with a weight of 25 plf is commonly used. However, the size of the beam may vary depending on the loads it needs to support.

In addition to the size of the beam, its material also plays a significant role in its load-bearing capacity. The most commonly used steel grades for I-beams are ASTM A992 and ASTM A572-50, which have higher yield and tensile strength compared to other grades.

Another consideration for selecting the size of the steel beam or RSJ for a 20 feet span is the type of end support used. If the beam is simply supported at the ends, which means it is held up at both ends, a smaller beam size and weight may be sufficient. However, if the beam is cantilevered, meaning it is only supported at one end and extends beyond the support, a larger beam size and weight are needed to resist the bending stresses caused by the overhang.

In conclusion, the appropriate size of steel beam or RSJ for a 20 feet span depends on various factors such as the type of load, type of structure, desired level of deflection, and end support. It’s important to consult a structural engineer to accurately determine the size of the beam needed for your specific project. Additionally, all designs must comply with building codes and regulations, which vary by location.


In conclusion, choosing the right steel beam size for a 20 feet span is crucial for the overall structural integrity and safety of a building. It is important to consider factors such as load and support conditions, as well as consulting with a structural engineer to determine the appropriate size. With the variety of size options available and advancements in technology, it is now easier than ever to find the perfect steel beam for your specific construction needs. By taking the time to carefully select the appropriate size, you can ensure a sturdy and durable building that will stand the test of time.


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