How To Read A Code Book:
Building code is confusing. Lets just get that out of the way right now. I am a building inspector and I still get confused! Luckly for homeowners and DIY'ers, one code book governs the bulk of all residential home code requirements. Regional code adjustments and amendments may be present due to geographic location and state objectives but for the most part, the IRC (International Residential Code) covers all the components of a residential house or duplex.
You might think: that's fine and great but how in the hell do you read this thing and know what it's actually saying? I am going to give a quick run down to keep you moving and hopefully provide you with the information needed to find what you are looking for.
First and foremost, make sure you get the edition of the IRC that governs your state (or the state that your project is within). Some states work under older editions while others will adopt the new code as soon as it's released. Code books are updated every 3 years, but states adopt them at different rates.
Once you have the right code book in front of you (or maybe you've found access to portions of it), start by looking through the index. Sometimes items are labeled differently than you might think they should be at first, so check different locations of the index to find the code you are looking for.
Don't Blame the Inspector!
Here's a side view of the 2018 IRC. The white pages are the code references and all the orange pages are amendments to the code by the state I live in! That's a lot of code and a lot of changes!
Before you go jumping into the book, also look at the definitions (in Chapter 2). Sometimes I catch myself spending all kinds of time trying to find what I am looking for throughout the pages of the code book, and it's listed right there plain as day in the definitions.
Now that you've hopefully found the section you are looking for, deciphering the meaning can sometimes be pretty straight forward and beyond confusing in others. I always recommend reading the section carefully and slowly, working through to interpret the meaning. Words like "shall" means you must, while "may" means it might be required depending on a specific condition.
Typically though, the IRC and most other ICC code books give the requirement that SHALL apply and then provides you with exceptions or a list of conditions or requirements that must be met for that particular code reference to take effect.
This code reference (to the right) talks about needing safety (tempered) glazing (glass) in a window. It states that all 4 conditions must be met to be considered a hazardous location, but then it provides exceptions for conditions where hazardous glazing can be omitted even if all 4 conditions are met.
In some instances, the code book will ask you to reference other chapters or sections. This is called "finding a code path" and by following the different pages and code sections, the right answer can be found.
This is why it's important to get the full code reference and not only of a section of it that might be found on the internet.
As always, when in doubt on what a code reference means for your project, give your inspector a call and talk it through. They are a great resource and can help steer you in the right direction!
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