Steel floor joists are horizontal load-bearing structures that transfer loads from floors above them to beams. Their high strength-to-weight ratios ensure a stable structure. Moreover, they are durable and resistant to moisture, mold, and pests. However, they are not common in residential buildings due to cost considerations.

Advantages and Disadvantages of Steel Floor Joists
Advantages of Steel Floor Joists | Disadvantages of Steel Floor Joists |
---|---|
High-Strength-to-Weight Ratio | Corrodes easily |
Resistant to moisture, mold, and pests | Limited availability |
Reduced noise and structural stability | Expensive |
Low maintenance | Higher heating and cooling costs |
Fire-resistant | Susceptible to lateral torsional buckling |
Remain stable during earthquakes and hurricanes | Not Flexible |
Easily recyclable | Difficult to transport |
Advantages of Using Steel Floor Joists
High Strength-to-Weight Ratio
Steel has the highest strength-to-weight ratio among all the materials used in construction.
This means that lesser amounts of steel can bear more loads compared to other materials, thus needing fewer supporting members.
This, in turn, reduces construction time, labor costs, and the volume of required material.
Steel having large load-bearing capacities can be used in cases where wood is not sufficient to resist heavy loads.
Moreover, a traditional lumber joist’s maximum span is much lower than a steel joist’s.
Resistance to Moisture, Mold, and Pests
Locations such as basements, roofs, and attics are all particularly prone to degradation. This leads to the rotting and wearing of wooden joist members.
To prevent damage, you can dry the joists.
It is best to use low-pressure fans in conjunction with dehumidifiers to maintain a dry environment.
In comparison, steel floor joists are more resistant to moisture effects and do not grow mold under them.
Steel floor joists are also resistant to rodents, termites, and other pests.
This makes steel a great material choice for basement beams in residential construction.
Reduced Noise and Structural Stability
Incorporating steel floor joists in flooring systems makes them quieter.
The squeaking noise that is observed while walking on traditional floors is due to the wear, warping, splitting, and cracking of the floor joists, which loosens the nails and bolts.
Steel joists can maintain their straight shapes and remain structurally sound for long periods.
Additionally, the bolts and nuts applied to steel floor joists are fewer and tighter than the ones used in wooden joists.
They are also less susceptible to sagging than wooden floor joists.
Low Maintenance
Once installed, steel floor joists maintain their strength for an extended period, reducing the need for frequent replacement.
Additionally, their use under floors demands minimal maintenance.
Fire Resistance
Steel floor joists are more resistant to fire as compared to wooden joists, as steel is a non-combustible material.
A good way to better protect steel joists is to coat them with fire-resistant chemicals, which allow them to be heat resistant even at very high temperatures.
High-density Spray-Applied Fire Resistant Material (SFRM) is a common chemical protection compound used to protect steel joists in the USA.

Location Specific Advantages
In areas prone to hurricanes and earthquakes, steel joists are a viable option.
They help to maintain the stability of structures during these conditions.
Sustainability
Steel can be recycled easily.
Moreover, they allow for energy-efficient construction with minimal impact on the environment.
Disadvantages of Using Steel Floor Joists
Corrosion of Steel
Steel is a highly corrosive substance. When exposed to moisture for long periods, it starts to rust.
To prevent corrosion, steel floor joists have to be painted periodically.
If not coated properly, steel joists lose their thickness at a rate of approximately 0.04 inches/year to 0.06 inches/year, ultimately leading to the collapse of the floor.

Availability and Initial Costs
In certain areas, there will be limited availability of steel.
Moreover, they also have higher investment costs than other alternatives like wood.
Thermal Conductivity
Steel has high thermal conductivity, resulting in higher heating and cooling costs.
Additional insulation is necessary to maintain the comfort of your home.
Buckling of Steel Joists
Buckling is a failure mechanism characterized by the bending of a structural member due to a compressive load surpassing the critical limit.
While steel is good both in tension and compression, it is susceptible to lateral torsional buckling due to applied loads.
This is because the average steel floor joist member is more slender as compared to its counterpart.
Limited Design Flexibility
Generally, steel joists are available in standard sizes and shapes in accordance with different codes.
Therefore, the customization of these joists is quite challenging.
Difficult to Transport
Since steel joists are heavier, they are difficult to transport to the construction site.
Additional labor and equipments are also necessary during the installation process.
Are Steel Floor Joists Better than Traditional Wood Joists?
Steel joists offer a variety of advantages over traditional wood joists.
Property | Steel Floor Joists | Wooden Floor Joist |
---|---|---|
Strength | High | Low |
Moisture Resistance | High | Low |
Combustibility | Non-combustible | Combustible |
Mold Development | None | Yes |
Cost | Expensive | Cheap |
Steel vs Wooden Floor Joists
Cost of Steel Floor Joists
Steel floor joists come at a cost of $100 to $400 per foot for residential construction.
As the floor span increases, steel floor joists become more expensive.
The cost also depends on the type of steel used.
Hot-rolled steel joists are thinner and less expensive, whereas cold-formed steel joists are thicker and have more strength but are also more costly.
The total cost of installing steel floor joists, including material, transportation, labor, and installation costs around $10,000 to $20,000.
Types of Steel Floor Joists
Open web steel joists are the most common type of steel floor joists.
These joists generally have a depth between 8” to 30” and span up to 60’.

Different types of open web steel joists are:
- K-Series
- KCS-Series
- LH-Series
- DLH-Series
- CJ-Series
While the K-series is common for residential applications, the KCS-series is a subset of the K-series.
It is common in situations with shorter-span requirements, where there is a need to adhere to shear and bending moment requirements.
Long-span-steel joists, or LH series, and Deep-long-span joists, or DLH series, are lightweight alternatives that longer span.
Among LH and DLH series, DLH series have longer spans covering over 100 feet.
In CJ series joists, steel and concrete are used to create a strong flooring system.
Frequently Asked Questions (FAQ)
Can I Replace the Floor Joists Without Removing the Floor?
It is possible to replace floor joists without removing the floor.
However, it is crucial to adequately support the floor using various techniques like sistering to prevent the collapse of your floor.
Are Engineered Floor Joists Better than Steel Joists?
Engineered floor joists are a more cost-effective and lightweight option than steel joists.
However, they are more expensive than wooden joists and are not as durable as steel joists.
Can I Use LVL for Floor Joists?
Laminated Veneer Lumber, or LVL, is a common choice for floor joists that reduces the risk of warping and shrinking than traditional joists.
They are created by bonding multiple layers of wood veneers under heat and pressure.