Steel Trusses vs. Wood Trusses: Which Should You Use?
Updated: Nov 23, 2022
Post frame buildings were originally developed in the 1930’s as a way to create a simple and cost effective structure. The primary motivation for the development of these large, free span buildings was additional storage. Technology in the agricultural industry, specifically in equipment, allowed farmers to cultivate more land creating a necessity of additional storage space for equipment and goods. Originally large poles were used for the building’s posts, hence the name “Pole Barn”.
As the post frame industry developed and improved, the poles were replaced with posts, superior metal roofing and siding provided better longevity and color options, and the hardware they held everything together became more effective at sealing out moisture.
All of these improvements helped to create a stronger, longer lasting post frame structure, but there was still one big problem with these kits that most everyone discovered in 2020 and 2021. Post frame structures require a lot of lumber. The wood trusses must be spaced at least every 24 inches on center; and often 18 or 16 inches on center. The close spacing of these wood trusses require a lot of material to build and a lot of labor to construct and install.
As lumber costs quickly began to rise in 2020 and 2021, home owners, farmers, and contractors began looking for lumber alternatives. During this period, steel trusses for post frame applications started to gain popularity.
But how did steel trusses become such an attractive lumber alternative?
First, of course was the cost. While an individual steel truss may be more expensive than an individual wooden truss, steel trusses can be spaced 10-12 feet apart, sitting directly on the building posts.
For example, if you are looking to cover a ten foot bay (distance between two posts) you will need two steel trusses or six wood trusses.
40’ Gable 4:12 Steel Truss: $600.00 x 2 = $1,200.00
40” Gable 4:12 Wood Truss: $270.00 x 6 = $1,620.00
Steel trusses will save you over $400 in materials costs for just this one bay, not to mention the labor you can save by installing just two trusses instead of six. Another cost to consider with wood trusses are header boards. The wood trusses require a surface to mount on between the posts. Normally this is a double or triple 2x10 board that spans between the posts. The header board requires the top of the posts to be notched, another labor intensive step of the wood truss installation.
Another cost consideration is predictability of the building material costs. The steel market is much more predictable and less volatile than the lumber market. Pricing for steel trusses will not experience the huge peaks and valleys one might expect with lumber. Because designing, purchasing, and installing a post frame building is normally a multi-month process, being able to depend on the initial price quote of the materials is a huge advantage. Many homes and post frame builds utilizing wood trusses were put on hold during the last couple of years because of the high price of lumber.
The second major advantage of steel trusses is their longevity. Steel trusses, like steel roofing, are designed to last a lifetime. The trusses are coated in a protective finish, preventing the steel substrate from rusting over time. When packaged, handled, and installed correctly, steel trusses and metal roofing panels should outlast every other part of the building.
Wood trusses have a tendency to warp and become distorted over time. This may be due to exposure to moisture from a roof leak or just the humidity of a non-climate controlled area. Because the steel trusses cannot absorb moisture and don’t have some of the density inconsistencies of lumber, they will not warp or bend when installed correctly.
The next benefit is ease of use. This advantage could be categorized directly with cost savings. Steel trusses are so easy to install many homeowners are able to completely eliminate labor costs by completing the installation themselves. Even if you do require a contractor to install the post frame kit, the labor cost for steel trusses will be much less than wood simply because of how easily the system installs.
On a 40x50 post frame building an installer would need to set just 6 sets of steel trusses, one for each set of posts. Alternatively, a contractor would be required to notch every post, set header boards, and install 26 sets of wood trusses to cover the same area. This may take multiple days, requiring a longer commitment of rental equipment.
True Metal Supply is able to provide construction drawings and an installation guide to anyone interested in learning more about proper installation of their specific building.
The final advantages of the steel trusses are functionality and appearance. Steel trusses can be ordered to clear span 8-100 feet. If your project is large or small, steel trusses are a practical component of any structure.
Steel trusses also offer better overhead clearance. Wood trusses require heavy timber support and a webbing design that normally fills the area below the roofline. Steel trusses are so strong they do not require this same type of design and allow for greater overhead clearance. Whether you want to build a second story or have enough clearance to pull an RV into a carport, steel trusses give the flexibility and functionality you need.
Steel trusses look great. The trusses present a matte black finish. Most customers love to leave their trusses exposed and visible but some choose to enclose and frame around the trusses to create a finished and residential look. The black trusses also create a sharp contrast to the white bottom of most metal roofing panels creating attractive lines against the background of the ceiling.
If you’re interested in saving money and creating a structure that’s beautiful and designed to outlast a generation, steel trusses are the perfect choice. If you need additional support with design or would simply like to learn more, please connect with us on the platform of your choice. We’re always here to help.
Design your own post frame building with steel trusses using our online Post Frame Builder.