Steel Beam Span Limits: Just How Far Can They Go?
- Madden Fabrication
- Jul 24
- 7 min read
Updated: Jul 29
Your project requires a high strength-to-weight ratio. You need to ensure structural stability for an extensive, open space. A steel beam is the perfect solution to provide the support you need, but the space you’re working with is as long as a country road.
Can a steel beam reach as long as you need it to? How far can a steel beam span?
You have questions, we have answers. Keep reading to learn more about how far a steel beam can span and the factors that may influence a safe distance for its length.
Table of Contents
How Far Can a Steel Beam Span?
It's not a one-size-fits-all answer. Many variables can influence how far a steel beam can span, and we’ll cover these factors later on in this article.
But first, the maximum beam span is determined by calculating its load-bearing capacity. An engineer will calculate the correct length for a steel beam with these factors in mind before beginning the metal fabrication process.
Madden Fabrication, located in Portland, is an expert metal fabrication facility serving all industrial, commercial, and residential construction industries.
With over 30 years of experience, Madden Fabrication has the knowledge to tackle even the most complex projects, including steel metal fabrication. Contact us to share details about your project and get a quote today.
How Far Can You Span a Beam Without Support?
It depends.
To keep your structure safe and efficient, there are key details to take into consideration. The engineer looks at the type and shape of the beam, the load-bearing requirements, and the material properties to determine the exact length the beam can be fabricated to.
6 Factors Influencing How Far a Steel Beam Can Span
#1: Beam Type/Shape
Steel beams come in various types and shapes. Some of the most common types of steel beams include:
I-beams: Also known as the universal beam, this beam is in the shape of an uppercase ‘I’ at the cross-section. Usually made using only one piece of steel, the ‘I’ shape effectively distributes stress, providing resistance to bending while maintaining stability. This design can sustain substantial loads using less material.
H-beams: An H-beam is a steel structure shaped like a capital ‘H’ at the cross-section and is fabricated by welding three pieces of steel together. The horizontal pieces (flanges) are welded to the vertical piece (the web) to create the H-shape. This type of beam has a large surface area at the cross-section, making it extremely strong and capable of covering long distances.
W-beams: Also known as wide flange beams, this type of steel beam is stout and sturdy due to its straight, larger flanges. The wide flanges are positioned perpendicular to the web, which is relatively thin, contributing to the beam’s efficiency and ability to span considerable distances.
Box beams: Box beams are hollow rectangular structures. Although lightweight, they are designed for strength and resistance to bending. Often used for decorative purposes or hiding pipes or wires, box beams can be used to create large, open spaces.
Hollow structural sections (HSS): Boasting tubular cross-sections, HSS are known for their versatility and come in either rectangular, circular, or square shapes. The closed section of HSS provides resistance to torsional loads, making HSS ideal for projects where twisting forces are present.
Truss beams: This type of steel beam is made up of a series of connected triangles forming a truss designed to distribute weight evenly. Truss beams allow for lightweight, strong structures, making them incredibly useful for covering large distances.
#2: Beam Size
The width, depth, and thickness of a steel beam will influence the strength and the length of how far you can span a beam without support.
Deeper beams can span further. For example, a taller I-beam has a greater moment of inertia, which makes it more resistant to bending and deflection. This allows the beam to span a longer distance without failing under stress.
For longer spans with minimal support, castellated beams can be an excellent option. Castellated beams are made by cutting a standard I-beam in a toothed pattern along the web and welding them back together to create hexagonal openings with greater depth.
Wider flanges and thicker webs promote strength in steel beams and can support heavier loads over longer spans. Larger spans generally require bigger and stronger beams.
Madden Fabrication can assist you with a custom design for projects of any size. We offer a full range of steel fabrication services, including cutting, welding, coating, and installation. We ensure accuracy and will work with you to develop custom solutions for your unique project.
#3: Material
Structural steel beams can be made using different materials, including:
Carbon steel
High-strength low-alloy steel (HSLA)
Stainless steel
Steel grades are classifications that categorize steel based on composition, properties, and intended use. Common steel grades used for steel beams include American Society for Testing and Materials (ASTM):
A36: ASTM A36 is a traditional and versatile carbon steel that is often used for general structural applications like plates, shapes, and bars. This hot-rolled, low-carbon steel is known for its weldability and affordability.
A992: ASTM A992 is generally considered higher-strength and is commonly used for projects that require greater resistance to seismic or wind forces, like high-rise buildings, bridges, or other projects that may require a beam to span farther with no support.
Concrete and wood are other material options used for beams. Concrete is known for its durability and fire resistance, but it is weaker in tension and is often paired with steel to reinforce bending. Wood is lighter and considered suitable for smaller spans, but it’s more susceptible to environmental conditions.
Steel outranks both of these materials in strength, making it the ideal material choice for spanning long distances.
#4: Load Conditions
Steel beams are designed by engineers based on the load that the beam must support, including:
Dead loads: Any permanent weight on the beam, such as the weight of the structure itself or any permanently attached elements to the structure
Live loads: Variable loads that can change over time, such as people, furniture, weather, or equipment
When considering how far a steel beam can span, it’s important to understand how different loads are applied to structures. Engineers must consider point load and uniformly distributed load (UDL) when designing a steel beam, as it’s crucial for structural integrity and safety.
Point load is a concentrated force on a single, specific point on a structure, like the weight of a column acting on a beam. UDL is a force spread evenly across the length of an area, like the weight of a wall evenly distributed along a beam.
#5: Deflection Limits
Steel beams limit deflection, ensuring structural integrity and preventing issues like sagging. Limits depend on load type and what the beam is being used for. Engineers will calculate the depth-to-span ratio to control maximum permissible deflection.
The allowable vertical deflection for steel beams is typically L/240, where L is the span of the beam. This limit is used for structural supports, such as for a building or bridge, and is considered the total load for both dead and live loads.
Other common deflection limits include:
L/360: For live loads alone, often used for floors or roofs that support plaster
L/180: Industrial storage beams designed for heavier loads
L/48 or L/600: Non-structural elements such as ceilings or partitions
#6: Structural Design
Several types of supports may be used to increase the span. Here are two types of supports that can help determine how far you can span a steel beam:
Columns: Intermediate support points are achieved by placing columns along the length of the beam. Creating multiple shorter span points of the beam allows for a longer overall beam span and heavier loads.
Walls: Acting as an additional support, walls help to redistribute bending and shear forces along the beam. The beam becomes stiffer with the extra support, granting a longer span without exceeding deflection limits.
How Far Can You Span a Steel Beam? General Span Guidelines
Different projects require different steel beam sizes. Here are some common sizes based on span guidelines:
150×75 I-Beam (6×3): This beam is often used in residential construction for smaller load-bearing tasks like supporting floor joists or lintels over windows and doorways.
203×133 I-Beam (8×5): This medium-sized beam is ideal for supporting floors or roof structures in commercial buildings. It can also be used to support heavier loads in industrial settings like factories and warehouses.
254×146 H-Beam (10×6): Used for industrial projects or large commercial buildings that require significant load-bearing capacity, this size of beam is robust enough to be used for projects such as high-rise buildings, bridges, and power plants.
As a general rule of thumb, a light load steel beam usually spans 20–25 feet, a medium load steel beam spans about 40–50 feet, and a heavy load steel beam spans 60 feet or more.
Standard steel beam sizes may not fit your project’s unique requirements, and custom steel beams may be necessary. Madden Fabrication can fabricate steel beams to your specific size and dimension requirements, ensuring a precise fit for your particular project.
Helpful Tips for Ensuring Proper Span of a Beam
When asking, how far you can span a steel beam, consider the following:
Deflection limits
Beam weight
Variable load weight
Proper beam size guidelines
Lateral supports
Fabricate Custom Steel Beams That Span the Distance and Will Withstand Your Load With Madden Fabrication
No matter how far-reaching your project is, Madden Fabrication has the capacity and expertise to handle your vision with diligence and precision.
We have extensive experience in structural steel fabrication, including components such as:
Box beams
Link beams
Grids
Trusses
Girders
At Madden Fabrication, we can fabricate a wide variety of products and develop custom solutions for both construction and industrial projects. Contact us today for a quote. We look forward to helping you reach your goals and bring your project to life.
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