Ontario Building Code - The Basics To Cover Your Ass

If you've ever tried to look through the Ontario Building Code (OBC) for answers, you might have felt thoroughly confused. I don't blame you.

I'll try to help you make sense of it. Before I do that, I want to briefly explain the purpose of the OBC and why it's important to have a basic understanding of it.

At a very high level, the OBC covers the technical requirements for construction (including renovation) and demolition of buildings and the change of use of existing buildings.

Essentially it's the bare minimum way of building and renovating.

You might have thought that building code requirements are only for new construction, but if you purchase an older home and intend to do any major renovations, it applies to you as well. Your designer, architect or contractor should obviously know the code fairly well, but it would be advantageous for you to have some knowledge and be able to quickly reference items.

It's sort of like having a basic understanding of taxes even though you're hiring an accountant to file on your behalf. 

Ultimately it's up to you and your responsibility to ensure that you do any major renovation or construction project according to the OBC.

Yes It's Confusing

If you've dug into it, you may have felt like you needed a degree in law to understand most of it. You may have given up in frustration after reading too many terms like  "notwithstanding", "except as permitted", and "in accordance with...." around five additional provisions.

It doesn't help that it continually bounces you around to numerous sections, sub-sections, clauses, sub-clauses, etc.

However, it's not that bad once you get a hang of the layout. So here's a very quick and dirty crash course.

The Basics

  1. New Publications Every Few Years - Currently we're using OBC 2012, with OBC 2006 before that. There are several amendments in between versions. OBC 2017 is coming up.
  2. The Building Code Act - This is a 40 page document that outlines the legislative framework governing construction. It's worth it to skim through this and get a feel for who's involved with what aspects of construction.
  3.  3 Divisions (A, B and C) - This is further subdivided into parts, and Division B is the one where the rules are. Don't worry too much about this.
  4. 12 Parts - This covers all construction. For new homes and renovations, the parts that you're most concerned with are Parts 9 and 11.
  5. The Numbering System - OBC uses decimal numbering system to identify particular requirements, as follows:
    1. 9.                                        Part
    2. 9.10                                    Section
    3. 9.10.19                               Sub-section
    4.                            Article
    5. (1)                      Sentence
    6. (1) (a)                 Clause
    7. (1) (a) (i)            Sub-clause
  6. Supplementary Standards SB - Detailed descriptions on how to properly build a component of the home. For example, SB-3 covers fire and sound resistance of building assemblies, while SB-12 covers energy efficiency.

There's a ton of other things, but we'll stop here, as this has probably covered more than enough aspects of the code that you need to know about at a very rudimentary level.

What's Important To You

Assuming you're working with simple residential homes, the two parts that are most important to you are Parts 9 and 11. Although other parts might play a role, these two are critical.

Part 9 covers new construction. But it's very important to know that it doesn't necessarily mean just a new house. Part 9 applies to even old houses with new parts built or even when portions have a change of use.

For example, if you tear out all your exterior basement walls, you will need to rebuild it according to today's insulation standards (R value of 20). If you were to build a new addition, all of it would have to comply with current codes in Part 9.

Part 11 primarily covers renovations for homes older than five years, where they make it less restrictive to comply with the rules.

If you were to build a legal secondary suite, you still need to comply as much as possible to Part 9, but would likely get some renovation exemptions to make it easier. For instance, in Part 9, the ceiling height for basements need to be 6'-11", whereas Part 11 allows for 6'-5", accepted by most Ontario cities.

Height requirements for basement suites

Height requirements for basement suites

Who Doesn't Love Free?

Of any state or province in North America, Ontario is the only one I know of that offers a free updated version of the building code online, even though it's not the full 2 volumes.

But the important parts we discussed above are covered. The latest revision was in January 2016. You can download the 700 page OBC right here:


Seriously, download it right now - I'll wait.

Do it before Ms. Wynne changes her mind and charges you!

Service Ontario - E-laws site

Service Ontario - E-laws site

Quick Exercise

Okay, got it? I'm going to ask you to do a quick exercise that I guarantee you will benefit from.

One of the biggest sources of confusion involves smoke and carbon monoxide alarms. Unlike other parts of the building code, these items are retroactive. This means even for old homes, you have to bring them up to today's standard. This is important for homeowners and landlords since it's a big safety concern.

I would like you to do a search in the document for these items, and post a couple of sentences in the comments section below on your interpretation on what needs to be done in an old house.

Here are the references in both Parts 9 and 11 (FYI - Control-F to do a search):

  • Smoke Alarms: 9.10.19 (Part 9) and C175 of Table (Part 9) 
  • Carbon Monoxide Alarms: 9.33.4 (Part 11) and C197 of Table (Part 11) 
Interconnected system of Smoke/Strobe/CO alarms

Interconnected system of Smoke/Strobe/CO alarms

If I get any comments, I'll reply back with my interpretation on what the requirements are.

Go ahead and do this, you'll learn a lot and start getting comfortable with the code, and at the same time figure out what the heck to do with those smoke and CO alarms.

Who Can You Rely On?

As a registered building code designer, of course I can assist if you need any help for major renovation projects or secondary suites.

But it's also important to ensure that any contractors you hire has a good understanding of it to avoid major headaches later on.  A good criteria when choosing a contractor is whether they know the basics of the code.

It's not a good sign if you ask them if their work complies with the OBC, and they respond with, "O.B. what??"

The sign of a good contractor is one who is willing to follow architectural plans and be subject to inspections - jumping up for joy is optional

The sign of a good contractor is one who is willing to follow architectural plans and be subject to inspections - jumping up for joy is optional