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When to Use Steel Floor Joist

May 14,2019

Tags:Cold Formed Steel, CFS Studs, Steel Floor Joist, LSF

Before engineered wood joists were invented in the late 1960s, builders used dimensional lumber to support their framing operations. These were moved aside with the creation of i-joists, named for their shape, in 1970.

Engineered wood joists made from plywood became more popular as the process to create them became more efficient and costs decreased. As steel mining became more practical over the years, metal was added to form steel-reinforced trusses, eventually giving way to steel joists.

The idea was, and still is, to create a better load-bearing system to support building structures, and to facilitate the open floor plans that became increasingly popular toward the turn of the century. Wood is still the most viable option in many construction projects, though durability and load-bearing capability makes steel floor joists an intriguing proposition for builders who are thinking long term.


The question then becomes: when is the best time to use steel floor joists?


Steel Floor Joist


5 Reasons it Makes Sense to Use Steel Floor Joists

  1. Steel has the highest strength/weight ratio of any material used for construction, so the same jobs can be completed with much less support using steel joists. This can affect time, labor costs, and the availability of each respective material. Also, the load-bearing capability must be considered, as some cases will prohibit the use of wood due to exceptionally heavy loads.

  2. Steel joists are ideal for areas like basements and attics that are subject to environmental conditions that would otherwise increase wear on wood counterparts. Steel is not at risk for mold growth from continued exposure to moisture, similar to conditions that might be found in a basement. It is also not as vulnerable to burrowing pests like rodents and termites that make their home in basements. Both materials can be treated with additional chemicals and primers to protect against wear, but wood will remain much more vulnerable to degradation than steel.

  3. Floors that use steel joists are quieter than wood. The creaking we hear walking across old wood floors is often due to the warping, splitting, and bowing of wood that leads to loose bolts and wayward joists. Essentially, support systems made with steel don't creak like those made with wood, and since steel floor joists are always straight, dimensionally stable, and maintain their shape much longer, they are an ideal option in scenarios where sound might prove an issue or needs to be minimized altogether.

  4. There are certain locations that have specific requirements where steel is the only option. A bridge in a place that is susceptible to flooding or earthquakes may have to use steel for the safety of people who will use it. Furthermore, many US states have mold-related legislation in place or pending, so contractors who want to avoid liability may need to include steel floor joists in their plans.

  5. Steel is one of the most recycled materials in the world, it doesn't consume trees, and has a 90% lower output to landfills than wood. Builders who are environmentally conscious or want to use “green” initiatives as a selling point can assure their consumers of the sustainability of steel floor joists.


If you want to save money in the short term on upfront material costs, use a wood system, but for long-term durability, sustainability, lowered noise, safety, and superior overall quality, steel floor joists are the way to go.