Truss vs. Web Joist

What's the Difference?

Truss and web joist are both structural elements used in construction to support the weight of a building. Trusses are typically made of wood or steel and consist of interconnected triangles that distribute the load evenly across the structure. They are commonly used in roof and floor systems. Web joists, on the other hand, are typically made of wood or engineered wood products and consist of a series of parallel chords connected by a web of smaller members. They are often used in floor systems to provide support and stability. While trusses are more commonly used for larger spans and heavier loads, web joists are often used in smaller residential or commercial buildings.


AttributeTrussWeb Joist
StructureFramework of beams forming trianglesHorizontal member supporting a floor or roof
MaterialWood, steel, or aluminumWood or steel
UsageCommonly used in bridges and roofsCommonly used in floors and roofs
SupportSupports loads along its lengthSupports loads perpendicular to its length

Further Detail


When it comes to building structures, choosing the right type of support system is crucial. Two common options are truss and web joist systems. Both have their own unique attributes that make them suitable for different applications. In this article, we will compare the attributes of truss and web joist systems to help you make an informed decision for your next construction project.


Truss systems are typically made of triangular units that are connected together to form a rigid framework. This design allows trusses to efficiently distribute loads and provide excellent support for roofs, floors, and bridges. On the other hand, web joist systems consist of a series of parallel chords connected by diagonal web members. This design offers flexibility in span lengths and load capacities, making web joists ideal for a variety of applications.


Truss systems are known for their high strength-to-weight ratio, making them a popular choice for large-span structures. The triangular shape of trusses helps to evenly distribute loads and minimize deflection. In comparison, web joist systems also offer good strength characteristics, but may not be as efficient as trusses for longer spans or heavier loads. However, web joists can be designed to accommodate specific load requirements, making them versatile in various construction projects.


Truss systems are typically prefabricated off-site and delivered to the construction site for installation. This can help to reduce construction time and labor costs. On the other hand, web joist systems are often assembled on-site, which may require more time and labor. However, the flexibility of web joists allows for easier customization and adjustments during installation, making them a preferred choice for certain projects.


Truss systems are generally more cost-effective than web joist systems due to their efficient design and ease of installation. Prefabricated trusses can be mass-produced, resulting in lower material and labor costs. In contrast, web joist systems may require more customization and on-site assembly, which can increase overall project costs. However, the versatility of web joists may justify the higher initial investment for certain projects.


Truss systems are commonly used in residential and commercial buildings, as well as bridges and industrial structures. Their high strength and efficiency make them suitable for a wide range of applications. Web joist systems, on the other hand, are often used in residential construction, mezzanine floors, and renovation projects. The flexibility of web joists allows for easy adaptation to different load requirements and architectural designs.


Truss systems are known for their durability and low maintenance requirements. Once installed, trusses can provide reliable support for many years without the need for frequent inspections or repairs. Web joist systems also offer good durability, but may require more regular maintenance due to their complex design. Inspecting and reinforcing web joists periodically can help to ensure their long-term performance and safety.


In conclusion, both truss and web joist systems have their own unique attributes that make them suitable for different construction projects. Truss systems offer high strength and efficiency, while web joist systems provide flexibility and versatility. When choosing between truss and web joist systems, consider factors such as design, strength, installation, cost, applications, and maintenance to determine the best option for your specific project requirements.

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