Codes and standards

Why it matters

Engineers do not invent safety rules from scratch for every project. Decades of experience, research and, sadly, failures are written down in codes and standards. Knowing which ones apply, which edition is in force, and how to read them is a core professional skill. On the FE and PE exams you will be expected to use them; on the job, failing to follow them can cost lives and licences.

Codes versus standards

The words are often used loosely, but there is a useful distinction:

• A standardA document describing how to do something well, such as a test method or bolt dimensions; voluntary on its own. describes how to do something well: how to test the strength of concrete, the dimensions of a bolt, the method for calculating wind loads, the safety requirements for a machine guard. On its own, a standard is voluntary.
• A codeA set of requirements written to be adopted into law; once adopted, it is mandatory in that jurisdiction. is a set of requirements intended to be adopted into law, usually by a government. Once adopted, it is mandatory in that jurisdiction. Codes often reference standards, which makes those standards mandatory too.

Example: a city adopts the International Building Code (a model code). The building code references ASCE 7 for structural loads and ACI 318 for structural concrete. Through that chain, the load and concrete standards become legally required for buildings in that city.

Who writes them?

Most US codes and standards are written by private, non-profit standards developing organisations (SDOs)Mostly non-profit bodies, such as ICC, ASCE, ASME and NFPA, that write codes and standards through volunteer committees. using committees of volunteers: engineers, manufacturers, regulators, insurers and users. Many SDOs follow a consensus process accredited by ANSI (the American National Standards Institute), with public review and the right to appeal. A few you will meet:

Government agencies also write mandatory rules directly, such as OSHA workplace safety regulations and state transportation department specifications.

How a model code becomes law

1. An SDO publishes a new edition of a model code, typically on a three-year cycle.
2. A state or local government adopts it, often with local amendmentsLocal changes a state or city makes when it adopts a model code, such as stricter snow loads. (for example, stricter snow loads in mountain areas).
3. Adoption takes time, so jurisdictions are often one or two editions behind the latest one.
4. The local authority having jurisdiction (AHJ)The local body, such as the building department, that reviews plans and inspects work for code compliance., such as the building department, reviews plans and inspects work for compliance.

That is why the first question on any project is: which code, which edition, with which local amendments? The answer is on the AHJ's website or from the building department, not on the cover of the newest book. Editions and adoption status change; check the publisher and your AHJ. For example, see the ICC at iccsafe.org and NFPA at nfpa.org. Checked on 2026-10-23.

A worked example

A mechanical engineer is designing a pressure vessel for a factory in Ohio. Questions to answer before calculating anything:

• Does the state require vessels to be built to the ASME Boiler and Pressure Vessel Code? (Most states regulate boilers and pressure vessels through a state inspector.)
• Which section and edition applies?
• Which ASTM material specifications are acceptable for the steel?
• Does the owner (the factory) have its own engineering standards on top of the code?

The design is then documented with references to the exact code clauses used, so a reviewer can check every step.

Common mistakes

• Using the newest edition when the jurisdiction adopted an older one (or the reverse).
• Treating codes as the goal. Codes are minimums. A design can meet code and still be a poor design.
• Ignoring local amendments.
• Quoting a standard from memory. Always cite the clause and edition you actually used.

Quick recap

• Standards are voluntary best practice; codes are written to be adopted into law and then become mandatory, often pulling standards in by reference.
• Most are written by consensus committees at SDOs such as ICC, ASCE, ASME, NFPA, IEEE and ASTM.
• Jurisdictions adopt specific editions with amendments, and the AHJ enforces them.
• Always confirm the code, edition and amendments before designing.