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Primary Modular Building Materials

The two primary modular building materials utilized in the structural frames of most units are wood and steel, the latter possessing unique advantages.

March 15, 2019

Modular construction is an innovative approach to large-scale building projects that can significantly improve efficiencies, reduce construction time, and even cut overall costs. Not all modular buildings are created equal, however. The materials used in modular building play important roles in dictating key aspects of the build’s overall scope, quality, strength, safety, durability and sustainability.

For the most part, the modular building materials are mostly the same materials as conventional construction projects. The composition of each modular unit’s structural frame is where different elements have the most impact. Similar to other components, these are fabricated at an offsite facility.

There are two primary modular building materials utilized to construct such frames: wood and steel.


Back in the days of the very first modular buildings, wood was the modular construction material of choice, and nowadays, it overwhelmingly remains the most commonly used for these projects, due to its abundance and cheaper initial costs. Wood-framed modular buildings, however, have several notable limitations that might give a property developer pause and may even prove more costly in the long-term repairs.


Wood often lacks the strength necessary to support large building projects, especially those of multiple stories. Due to this weakness, wood-framed buildings are typically no taller than a few stories—a considerable limitation for someone looking to build a hotel or apartment building, as examples.


Wood is flammable and vulnerable to fire, which could severely damage the structural integrity of the building, requiring replacement, or even worse, leading to a total collapse.


Wood has a tendency to warp over time, resulting in a lower quality building in the years after completion. Combined with its susceptibility to pests and mold, selecting wood for a modular structure may prove to be the more expensive choice in the long term, considering repair costs—even despite initial savings.


Wood is among the most wasted materials used in modern construction. On average, 20% of construction lumber typically ends up in landfills, leaving a larger environmental footprint than other alternatives.


The other major choice of material for modular frame construction is steel, with several significant advantages over wood.


Given its superior strength, steel modular unit frames can support structures of greater heights. iBUILT is one of the few firms capable of building modular structures taller than 30 stories.


Steel is a noncombustible material, making it the safer choice and reducing the risk of sustaining severe structural damage due to fire.


Steel is resistant to warping, pests, and mold, resulting in a building that will retain its strength and quality for much longer than wood, without the need for significant repairs.


Steel is among the most efficiently used building materials, with an average of only 2% wasted during the course of a project.

Choosing steel is not the end of the decision process, as there are multiple varieties to choose from. When it comes to steel, there are two framing system choices – structural steel, commonly known as “black iron,” or light-gauge stud framing, made of cold-rolled steel. The primary difference between the two structural systems is the height of the structures they can support.

Light gauge steel framing is effectively a noncombustible steel substitute for traditional wood stud framing, which can generally be used for buildings as tall as eight stories, but not taller. To go above eight stories, one would need to use structural steel or black iron.

iBUILT has chosen steel as its material of choice for all building projects and is one of the few American firms capable of working with structural steel.

Building Material Control in Modular Construction

Whether a modular builder uses steel or wood, the modular construction company will be able to more efficiently inventory and purchase raw materials without the worry of loss, delay or damage. Additionally, with offsite construction in a controlled environment, inventory control will be much easier without concerns of loss or weather damage, as frequently occurs with onsite construction projects.


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