The Architect's Guide to Exposed Structural Steel (AESS)

The Architect’s Guide to Exposed Structural Steel (AESS)

When considering different structural design options, Architecturally Exposed Structural Steel stands out to many architects since it boasts both aesthetic appeal and structural integrity. This post explores all you need to know about the method if you plan to integrate it into your designs.

Background: What is AESS?

Exposed Structural Steel (AESS) refers to a type of steel construction in which the structural steel elements are intentionally left exposed and visible as a design feature, rather than being concealed behind finishes or cladding. AESS requires careful detailing, fabrication, and installation of the steel members to meet specific visual and performance criteria.

AESS is typically used in buildings, bridges, and other structures where the exposed steel elements are intended to be a prominent architectural feature. This can include steel columns, beams, braces, trusses, and other structural fixtures. AESS may have special requirements for surface preparation, welding, and connection detailing to achieve the desired appearance and performance.

The Five Levels of AESS

A graphic listing the five levels of AESS (Exposed Structural Steel)

The five categories of AESS, or Exposed Structural Steel, are as follows:

AESS 1 (Basic Exposed Steel): This category typically involves steel members with a basic level of fabrication and finish. The steel elements may have minimal surface preparation, simple welds, and basic connection details. The appearance of the steel may have some variations in color, texture, and surface imperfections, but they are straightforward designs.

AESS 2 (Standard Exposed Steel): This category requires a higher level of fabrication and finish. The steel elements must have more refined surface preparation, higher-quality welding, and more precise connection details. The appearance of the steel should have a consistent color, texture, and surface quality, with minimal variations.

AESS 3 (Enhanced Exposed Steel): This category involves steel members with a higher level of fabrication and finish, intended for more prominent architectural features. The steel elements must have refined surface preparation, precise welding, and detailed connection details. The appearance of the steel should have a uniform color, texture, and surface quality, with essentially no variations. AESS 3 should achieve a high level of fit and finish, and additional treatments or coatings may be applied.

AESS 4 (Highly Finished Exposed Steel): This category is the highest level of fabrication and finish for exposed steel elements. The steel members must have the highest level of surface preparation, precision welding, and intricate connection details. The appearance of the steel should have a flawless and uniform color, texture, and surface quality, with no visible imperfections. AESS 4 is typically used for premium architectural features where the steel elements are expected to have a high level of visual appeal and must meet stringent aesthetic requirements.

Finally, there is Custom AESS, known as AESS C. Custom AESS requirements do not fall into any of the above categories due to specific requirements of the design’s structure or appearance. For example, the design may request that sharp edges are not ground smooth.

Concepts Architects Working with AESS Should Know

As an architect working with Exposed Structural Steel (AESS), it is important to have a solid understanding of the following key aspects:

Aesthetic Requirements: AESS is often used to create architectural features or to express a particular design vision. Therefore, understanding the desired aesthetic requirements and visual appearance of the exposed steel members is crucial. This includes considerations such as surface finish, color, texture, and detailing. Being knowledgeable about different fabrication and finishing techniques for steel, such as grinding, polishing, or texturing, can help you achieve the desired aesthetic outcome.

Structural and Design Considerations: AESS is an integral part of the overall structural system of a building or structure. Understanding the structural requirements and design considerations related to AESS is crucial. This includes comprehending load-bearing capacities, connections, framing, tolerances, and interactions with other building systems.

Fabrication and Installation: Familiarity with fabrication and installation processes for AESS is essential. AESS may require higher levels of accuracy and precision in fabrication and erection to achieve the desired aesthetic outcome. Being knowledgeable about fabrication techniques, tolerances, and best practices for handling, transportation, and installation of AESS can help ensure that the exposed steel members are installed correctly and meet the intended design vision.

Material Selection and Corrosion Protection: Understanding the different types of steel, finishes, and corrosion protection options available for AESS is important. This includes knowledge of various steel grades, surface treatments, and coatings, such as galvanizing, painting, or powder coating, and their impact on the performance, durability, and aesthetics of the exposed steel members.

Coordination with Other Trades: As an architect, coordinating with other trades and disciplines involved in the construction process is critical. This includes collaborating with structural engineers, steel fabricators, contractors, and other design professionals to ensure that the AESS is integrated seamlessly into the overall design and construction process.

Codes, Standards, and Regulations: Familiarity with relevant codes, standards, and regulations related to AESS is essential. This includes understanding the applicable building codes, industry standards, and local regulations that govern the design, fabrication, and installation of AESS. Compliance with these requirements is crucial to ensure structural integrity, safety, and regulatory compliance.

Communication and Collaboration: Effective communication and collaboration skills are vital when working with AESS. This includes communicating clearly with the project team, clients, and stakeholders, and collaborating closely with steel fabricators, contractors, and other design professionals to ensure that the design intent and aesthetic requirements for AESS are effectively conveyed and implemented throughout the project.

Can You Galvanize AESS?

Yes, it is possible to galvanize Exposed Structural Steel (AESS). Galvanizing AESS can provide effective corrosion protection, as the zinc coating forms a durable barrier that helps prevent rust and corrosion. Galvanized steel also has a long service life and requires minimal maintenance, which can be advantageous in certain applications.

It’s essential to consult with experienced professionals, including structural engineers, architects, and galvanizing experts, to determine the most appropriate corrosion protection strategy for AESS based on the project’s aesthetic considerations and maintenance expectations. Proper planning, detailing, and execution are crucial to achieving the desired aesthetic and functional outcome when galvanizing AESS.


Architecturally Exposed Stainless Steel is an excellent method for showcasing intricate structural design. It highlights the complexity involved in creating massive structures and allows people to see the intricate details of the buildings around them. There are multiple different approaches and types of AESS.

When looking for a partner to collaborate on a project with AESS, you want expertise that you can rely on. Novum Structures’s quality management system is ISO 9001 certified in the fabrication and installation of architectural structures. Novum Structures engineers are here to collaborate with your team to create a structural steel system to accomplish your design intent, contact us today!