Synopsis: Every three years, the International Residential Code (IRC) is updated. The 2015 version of the IRC includes hundreds of changes and new provisions. Code expert and building official Glenn Mathewson has compiled a guide showing the new code’s most notable changes, with an illustration that helps to show each change being discussed. The changes are grouped in four enforcement areas as they appear in the code book: building, electrical, decks, and plumbing and mechanical. This important feature article discusses 20 significant code changes for 2015.

The latest building-code requirements typically start becoming the law of the land a year after they’re published, so it won’t be long before you’ll need to comply with new provisions in the 2015 International Residential Code (IRC). A quick shuffle through the 902 pages of the new code book reveals that most have a black bar in the margin, signaling a change. There are hundreds of changes, but most are editorial, intended to make the respective provisions easier for builders to understand and easier for code officials to interpret. Still, there are significant changes of substance as well. Here, I highlight those that I think will have the most far-reaching effects and the ones that code officials and builders should be most aware of. The changes are grouped in four categories: building, plumbing and mechanical, electrical, and decks.

BUILDING

Fire and injury prevention is still the emphasis, but the code also reflects changes in society’s attitudes. Recent revisions to the IRC brought on by tiny-house advocates demonstrate that anybody can lobby the International Code Council—which is comprised of municipal code officials and interested parties—for changes.

ELECTRICAL

Electrical codes in the IRC come from the National Electrical Code (NEC), published by the National Fire Protection Association (NFPA). Like the IRC, this code is…