Unwritten Building Code Requirements | Jensen Hughes

Understanding Unwritten Code Requirements

Rick Glenn, PE

Rick Glenn explains the importance of understanding the two different types of "unwritten" code requirements.

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Engineers and building code consultants have an obligation to their clients to be familiar with the litany of code requirements pertaining to fire and life safety. It’s also their obligation to know both the written and unwritten code requirements.

What do we mean by “unwritten” code requirements? There are two types. The first type is an interpretation of a published code requirement by the local code authority. This generally occurs when the written requirement is vague or lacks sufficient detail to clearly explain the requirement.

The second type are requirements that are not published but have historically been enforced by the local code authority. The following are a few examples of “unwritten” code requirements.

Unwritten Code Requirements: Local Authority Interpretation of Published Code

The Chicago Building Code includes requirements for fire alarm one-way and two-way voice communication systems for new high-rise buildings, and for certain types of existing high-rise buildings. The local code officials do not permit automatic occupant notification in high-rise buildings.

Occupant notification is done by the responding fire department personnel, at their discretion, upon arriving at the site and assessing the situation. If necessary, occupant notification is accomplished via the one-way voice communication system (e.g. speakers on each floor connected to the fire command panel). This would not be apparent to someone not familiar with City of Chicago requirements.

Similarly, the Chicago Building Code does not include requirements for— or prohibitions against — manual pull stations in high-rise buildings. However, the installation of manual pull stations in high-rise buildings is prohibited by the local code authorities.

These cases are examples of unwritten code requirements that have historically been enforced for many years. These requirements are frequently misapplied by out-of-state designers who are unaware of these unwritten code requirements.

Unwritten Code Requirements: Non-Published/Vague Requirements Enforced by Local Authorities

A past project included reviewing and confirming specific code requirements imposed by the local fire official in a suburb of Chicago. The project involved the construction of a new 6-story condominium building. The developer was concerned about the local fire official requiring smoke vents in the building. Knowing that smoke vents in a multi-story residential building made no sense, the engineering consultant assumed there was some miscommunication between the developer and the local fire official.

Upon reviewing the local code for that municipality, there was a requirement for smoke vents for all new multi-story residential buildings. Not knowing the rationale behind a such a requirement, the engineering consultant met with the local fire official to discuss the issue. During this meeting, local fire officials clarified that they did not require smoke vents; they wanted a manually activated, mechanical smoke exhaust system to serve the corridors on each floor of the building. The only problem was that there was nothing in their code that stated such. This is an example of a poorly written code requirement where the literal wording of the requirement was not consistent with what the local authorities were enforcing or wanted

Another example involved the construction of a new 3-story, single tenant retail building in a Chicago suburb. Although the building was only 3 stories in height, the floor area per floor exceeded 30,000 sq. ft. After reviewing the local code requirements, there was nothing too unusual except for one rather vague requirement that pertained to buildings having fire sprinkler systems. There was a requirement that a minimum of one floor drain had to be provided for every 5,000 sq. ft. of floor area for each floor, regardless of the type of building

Being a single tenant retail building, most of the building constituted large, undivided floors that were public areas. How could the design team provide the required number of floor drains for a building of this type without adversely affecting the public areas? What was the reason behind the requirement? In meeting with the local code officials, they explained that the rationale for the requirement for the floor drains was to assist the fire department in mop-up operations after a fire and/or a sprinkler system activation. During the meeting, the justification for a code variance was discussed given the nature of the building. The end result was that a formal code variance to reduce the number of floor drains was granted by the local authority.

The above cases are just a few examples of “non-written” or vague code requirements. It’s important for engineers and code consultants to know not only the written code requirements, but also local practices and local authority interpretations to properly assist their clients. As members of national and global regulatory organizations, we always have our fingers on the pulse of code and standard interpretations to help advance your project and mitigate risk.

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