Steel floor joists are horizontal supports that comprise the substructure of a floor. These supports are made from high-grade steel that is strong and durable, but also somewhat heavy when compared to other joist materials. The advantages of steel floor joists include unrivaled strength and durability, excellent quality and uniformity from one beam to the next, and unrivaled straightness. These joists are also very likely to resist water damage, mold, bug infestations, and other types of damage that wood joists tend to be susceptible to. While the cost of steel joists may be higher, they are less likely to need replacement over the lifespan of a structure.
A common problem with wood joists is expansion and contraction due to varying levels of moisture. Steel floor joists are not as susceptible to such expansion and contraction, which means the steel will be far less susceptible to cracking, warping, or other damage that can happen to wood. Nails and screws will be less likely to be jostled out of place as a result of the lowered risk of expansion and contraction as well, meaning a higher level of structural stability is possible. In addition, steel floor joists are less likely to have imperfections that can compromise structural integrity.
If a building must meet certain fire codes, steel floor joists are great choices. Steel is fire-resistant, and it is far less combustible than wood and other types of building materials. The overall structure of the building is less likely to be damaged in the event of a fire as a result of the fire resistance of steel. Depending on local or regional fire codes, using steel floor joists may allow the builder to increase floor or ceiling space within compliance of fire regulations, since steel is generally a non-combustible material when used for certain applications.
Using steel floor joists can even improve the air quality in a home. Wood and other joist materials tend to be susceptible to mold and mildew build-up, which can negatively affect the air quality within a home. Mold and mildew does not build up on steel, thereby eliminating a potential threat to air quality and the health of the home's inhabitants. Wood is also often treated with chemicals that help resist water damage, but steel needs no such chemicals, thereby eliminating yet another possible contaminant of air quality within the home. Steel can be considered more environmentally friendly than wood as well, since steel can be recycled and production impacts are often lower.