I am having difficulties understanding the relationships between the International Residential Code (IRC) and national and/or local building codes. What’s the hierarchy? How do I determine whether my local code recognizes a clause in the IRC?
The IRC no longer recognizes moisture-resistant, paper-faced
drywall (“green board”) as a suitable tile backing material in wet areas such as tub and shower surrounds.
I’m from Canada, and I don’t think my national and local codes have this stipulation.
These entries from the IRC might help better understand how they fit with your province or local building requirements.
The IRC is a basic guideline for the safe building of a residential structure.
Any law that states other requirements than what is set forth in the IRC takes precedence over the IRC.
The building codes can not account for all manufacturer specifications and as a result the manufacturer’s specifications take precedence over the contents of the IRC. Also the IRC will reference other standards for building and these are noted in the applicable section. Also at the end of the IRC in an appendix is a list of referenced standards. The IRC can not physically encompass within its pages all the various standards out there nor can they constantly change the IRC when other standards might change.
Your local Building Official (the local Building Inspections Department) can render interpretations of general or unclear sections of the codes. The BO can write amendments to the codes that take into account local variations and requirements that the IRC does not account for.
In a nutshell the IRC is a guide for governments and manufacturers to follow but either of those entities can change what the IRC states/requires. One last aspect are licensed Professional Engineers who can bypass the IRC requirements if the item the IRC covers has been “Engineered” and the Engineer provides their stamped/sealed/etc/ plans demonstrating what the change is and has used acceptable engineering practices in their design.
As for what your local Building Official recognizes you should ask them, or view their WEB site to see, if they have issued any local amendments to the IRC and what, if any. Provincial amendments they follow.
Emmanuel Scanlan, thanks for taking the time to post your detailed reply.
I see that the IRC does not nullify any provisions of local codes, and manufacturer’s specifications take precedence over the contents of the IRC.
So, this seems to be relevant in situations were local codes are more strict/stringent than the IRC. What about the opposite? What if the IRC mentions a clause that a local code doesn’t?
Back to my example: the IRC no longer recognizes moisture-resistant, paper-faced drywall (“green board”) as a suitable tile backing material in wet areas such as tub and shower surrounds. However, there is no such language in my local/national building code.
Do I have a case again my builder that is using green board in my shower stalls. Can I reference the IRC?