2021 International Mechanical Code (IMC) – ICC Paperback

The 2021 International Mechanical Code (IMC) is the International Code Council’s 2021-cycle code for HVAC, exhaust, duct, and refrigeration systems, in the ICC paperback edition for contractors, inspectors, and engineers in jurisdictions enforcing 2021.

Although ICC has since published the 2024 edition, the 2021 IMC remains the enforced mechanical code in many states and cities, and it is the edition named on a large number of contractor license exams. It uses the same prescriptive-plus-performance structure as other I-Codes, so new equipment and methods can be approved on demonstrated performance.

What's included

• 2021 International Mechanical Code, complete text, paperback
• Publisher: International Code Council (ICC)
• ISBN-13: 9781609839642
• Covers ventilation, exhaust systems, duct construction, combustion air, chimneys and vents, boilers, refrigeration, and hydronic piping

Who it's for

HVAC and mechanical contractors bidding or permitting work in 2021-cycle jurisdictions, mechanical inspectors and plan reviewers who must enforce the adopted edition, and candidates for state mechanical licenses or ICC certifications that reference the 2021 IMC. Commercial kitchen and dryer-exhaust installers will find the 2021 changes directly relevant to their work.

Why this edition

The 2021 cycle made a number of practical changes: clothes dryer exhaust terminals must be at least 3 feet from building openings, spray foam on exterior ducts in attics and crawl spaces must meet flame and smoke index limits, fire and smoke dampers need approved inspection access, refrigerant tables were updated for newer refrigerants, condensate terminations require identification and discharge limits, factory-built combination intake/exhaust terminations are permitted, whole-house balanced ventilation minimums were reduced by 30 percent, nail-salon station exhaust must run continuously, and grease ducts need a horizontal cleanout within 3 feet of a horizontal discharge fan. If your jurisdiction enforces 2021, these are the rules an inspector will cite.

Frequently asked questions

Is the 2021 IMC still in use?

Yes. Many states and municipalities adopted the 2021 I-Codes and have not yet moved to 2024. Confirm the adopted edition with your building department.

What changed in the 2021 IMC for dryer exhaust?

Dryer exhaust terminals must be located at least 3 feet from any opening into a building.

Should I buy the 2021 or 2024 IMC for a contractor exam?

Buy the edition listed in your exam candidate bulletin. Section numbers and some tables differ between cycles.

Details