Why Building Codes Evolve with Time

In the United States, the most widely adopted building codes are the International Codes or I-Codes which are developed by the International Code Council (ICC). These model codes include the International Building Code (IBC), International Residential Code (IRC), International Fire Code (IFC), International Energy Conservation Code (IECC), among others. States and local jurisdictions adopt and amend these codes to fit their regional needs.

But building codes are not static. They are dynamic documents, revised regularly - often every three years - in response to new knowledge, emerging technologies, changing societal values and sometimes tragic failures. This blog explores the key forces behind the evolution of building codes and highlights how those changes reflect broader shifts in the way we live and build.

Learning from Tragedy: How Disasters Shape the Codes

One of the most powerful drivers of building code evolution is lessons learned from past failures - particularly those involving catastrophic loss of life.

A defining example occurred in 1942, when a fire broke out at the Cocoanut Grove nightclub in Boston, Massachusetts. The blaze claimed 492 lives, making it one of the deadliest nightclub fires in U.S. history. Many deaths were attributed to inadequate exits, doors that opened inward and highly flammable interior finishes. As panicked patrons rushed to escape, they became trapped at exits that were either locked or poorly designed to accommodate emergency egress.

In response, fire and building codes underwent substantial revisions. These included:

• Requirements for a minimum number of exits in assembly spaces;

• Exit doors that swing outward, in the direction of travel;

• Clearly illuminated exit signage and emergency lighting to guide evacuation during a fire.

These changes became the foundation for modern egress design standards that are still in place today.

Shaking Foundations: Northridge and the Push for Seismic Code Changes.

More recently, natural disasters like the 1994 Northridge Earthquake have prompted sweeping updates to structural codes. Northridge, located in the San Fernando Valley of Los Angeles, experienced a magnitude 6.7 earthquake that exposed critical vulnerabilities in:

• Steel moment-frame buildings, which suffered fractures at welded connections;

• Wood-frame soft-story structures, typically with open ground floors for parking and limited lateral resistance.

Although many buildings did not collapse, numerous structural failures were hidden within critical connections which prompted a deeper understanding of seismic performance.

The earthquake led to major changes, including:

• Revised seismic detailing requirements for steel moment frames;

• Improved welding specifications and inspection protocols;

• Adoption of mandatory soft-story retrofit ordinances in high-risk jurisdictions such as Los Angeles and San Francisco.

Embracing Innovation: Technology as a Driver of Change

Another driver of code change comes from advancements in Technology. As new materials, systems, and methods enter the construction industry, codes must evolve to regulate their safe and effective use.

For example:

• Cross-laminated timber (CLT) has pushed codes to address tall mass timber construction;

• Advanced HVAC systems with smart controls and high-efficiency performance demand new guidance;

• Modern fire detection technologies have changed how we design for occupant notification and fire suppression.

Beyond products, scientific research in structural engineering, energy modeling, indoor air quality, and fire behavior continues to shape best practices. As research leads to better understanding, codes are updated to reflect the latest knowledge and performance standards.

Shifting Priorities: From Strength and Safety to Sustainability and Inclusion

Finally, while life safety remains central, modern codes increasingly reflect evolving societal values, including:

• Environmental sustainability;

• Accessibility for all users;

• Adaptability to climate change.

This transition is visible in the contrast between past and present construction practices. Historically, concrete and masonry were used extensively, even for interior partitions. Today, light-frame systems using lumber or light-gauge steel dominate, offering faster, more flexible, and resource-efficient construction.

Similarly, past buildings often featured small windows, due to structural limitations and concerns over heat loss. In contrast, modern buildings increasingly incorporate large windows for natural daylighting, made possible by advances in materials and energy codes.

Many jurisdictions (like California) now mandate solar panels on new buildings as part of their energy code, reflecting a broader commitment to renewable energy and carbon reduction.

Perhaps most transformative is the push for universal accessibility. Where stairs once restricted access, modern codes require ramps, signage and barrier-free circulation, ensuring that the built environment is inclusive of people with disabilities or mobility challenges.

In the end, building codes are not static documents - they are living frameworks that respond to changing knowledge, technology, and societal values. Updating them is not only a technical necessity but also a moral imperative. It is the civic duty of all stakeholders to ensure that the built environment reflects the evolving needs, priorities and aspirations of the communities it serves.

If you'd like to explore these ideas further and see how building codes are adopted, evolve, and enforced across the United States, please check out my YouTube video on this topic. Visit Conventional Framing Academy for courses on residential structural design.