# Determine whether a building be regulated by part 3 or part 9 OBC



## alayan (Sep 12, 2018)

Hello everyone,
I'm taking my first OBC course, and I have an exercise on how to distinguish between part 9 and 3 of the OBC. For what I understand, part 9 technically applies for building having 3 storeys or less, and building area is no greater than 600 sm. But in the diagram, there is an overhang on the ground floor and a deck on the third floor which make me confused. 
1/ Would a deck or a partial overhang contributes in building area?. 
2/ Since there are 3 different major occupancies (1st floor- Coffe, 2nd floor- Retail, 3rd- Rooming house), What is the occupancy classification of the building?
Thank you so much


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## tmurray (Sep 14, 2018)

Hello Alayan,

First, want to check 1.1.2.2 of Division A to see what building classifications fall under Part 3 jurisdiction. Anything that is not listed here, we would generally call a Part 9 building.
Next, you want to check Section 1.4 of Division A for the definition of building area. This tells us exactly how to measure the building area. Important note here is that floor area and building area are similar, but different and are used for different things in our codes.

Building area is the greatest horizontal area between exterior walls or between exterior walls and the centerline of firewalls, so in your example an overhanging portion of the building only counts towards the building area if it has exterior walls. Decks would not.

Coffee shop occupancy classification (letter type) would be based on the total occupant load (#of people). Going off memory here because I'm not in Ontario (this is an OBC only thing), but I believe if it is not more than 30 people, you can classify it as an E - mercantile, otherwise it is an A2 - Assembly
Retail is E - mercantile
Rooming house would be C - residential

Once we have the individual occupancies, we can classify the occupancy of the building. You will imagine a building of number of storeys your building for each of your occupancies. Look at 3.2.2.4 to 3.2.2.8 for some guidance here especially if you have small occupancies that might not need to be considered (less than 10% of the *floor area* of the storey it is located on). now we look at 3.2.2.20 to 3.2.2.82 for your 2 to 3 options based on if the coffee shop is an A2 or not.

The way the titles are laid out is the <occupancy><number of stories><sprinklered or not> ex. 3.2.2.59. Group E, up to 3 stories. 

In the above example we have a group E that is permitted to be constructed up to 3 stories in height and does not require sprinklered (buildings requiring sprinklers simply state "sprinklered" at the end).This looks like it will fit for the E classification we found earlier, but it might not. This specific classification has a maximum building area based on the number of streets (streets is a defined term) and the number of storeys (we could use this classification for a 1 or two storey building as well). So, we have one of the classifications to compare. 

Once you other ones and what we are looking for is the fire separation requirements. we need to compare what the required fire separations are for each building and the most restrictive case will dictate the classification of our building. For instance, in our example: floors, combustible mezzanines, combustible load bearing walls columns and arches must all have a fire resistance rating of 45 minutes. If your other classification requires an hour or more, or requires a roof fire resistance rating as well as the other ratings, then this will be the "building classification"

When a building official asks you what your building classification is, we want to know which 3.2.2 section you designed the building to.

Hope this helps and feel free to ask any other questions you have.


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## alayan (Oct 3, 2018)

tmurray said:


> Hello Alayan,
> 
> First, want to check 1.1.2.2 of Division A to see what building classifications fall under Part 3 jurisdiction. Anything that is not listed here, we would generally call a Part 9 building.
> Next, you want to check Section 1.4 of Division A for the definition of building area. This tells us exactly how to measure the building area. Important note here is that floor area and building area are similar, but different and are used for different things in our codes.
> ...


Thanks a lot Murray


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## Rick18071 (Oct 5, 2018)

What is OBC? I have a feeling it is not one of these:

OBC Other Backward Classes
OBC Oriental Bank of Commerce (India)
OBC Original Broadway Cast
OBC Ontario Building Code
OBC Oriental Bird Club
OBC Original Bedstead Company (UK)
OBC Online Booty Call (website)
OBC On Board Computer
OBC Organization for Bat Conservation
OBC Outline Business Case (UK government procurement)
OBC On Board Credit (cruise industry)
OBC Officer Basic Course
OBC Original Birth Certificate
OBC Order of British Columbia
OBC Ocean Bottom Cable
OBC Outside Back Cover
OBC One Button Checkup (Norton Utilities)
OBC Obscured by Clouds (Pink Floyd album)
OBC Outer Banks Conservationists
OBC Online Business Center
OBC Overseas Briefing Center
OBC Overseas Basing Commission
OBC Office of Bar Counsel
OBC Optical Bar Camera
OBC Open Bible Church
OBC Outside Broadcast
OBC Outbound Call (call centers)
OBC Out of Band Control
OBC Outboard Boating Club
OBC Orange Belt Conference
OBC Onslaught Block Constructed (gaming)
OBC Old Boy's Club
OBC Open Birth Certificates (adoption)
OBC Obligations à Bon de Conversion
OBC Organic and Biochemistry
OBC Oakmont Booster Club (Ashburnham, MA)
OBC Overhead Bridge Crane
OBC Officer Billet Code
OBC Operating Budget Committee
OBC Open Building Control (Italy)
OBC On-Orbit Calibrator
OBC Organização de Base Comunitária (Portuguese: Community Based Organization)
OBC Outrageous Builder's Club (gaming)
OBC Oostzaanse Bridge Club (Amsterdam, Netherlands)
OBC Off-Boresight Compensation
OBC Optical Bench Enclosure (NASA)
OBC Oracle Business Component
OBC Ossa Bene Cubent (Latin: The Bones Rest Well, epigraphy)
OBC original brats creations
OBC Oxford and Bermondsey Club (UK)
OBC Organically Bound Chlorine
OBC O'neil, Bothun and Cornell
OBC Orange Bowl Committee (est. 1935)
OBC O2 Binding Curve
OBC Oregon Burn Center (Portland, OR)
OBC Operation Boot Camp (fitness; various locations)
OBC Online Bible College


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## north star (Oct 5, 2018)

*@ ~ @ ~ @*

Possibly, ...the Oregon Building Code !

@ ~ @ ~ @


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## Builder Bob (Oct 5, 2018)

I believe it may be further North - as In Ontario Building Code????

In the fire service, Ontario Fire Codes are very progressive and a great resource


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## Francis Vineyard (Oct 5, 2018)

Well let's see alayan is from Ontario and tmurray is from Canada, so it's probably french


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## ADAguy (Oct 15, 2018)

Be "nice" guys to our northern friends.


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## mark handler (Oct 15, 2018)

Current Oregon Building Code is Based on the 2012 International Building Code (IBC)


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## Pcinspector1 (Oct 15, 2018)

Francis Vineyard said:


> Well let's see alayan is from Ontario and tmurray is from Canada, *so it's probably french*



Oui! 

So glade we got tmurray in goal since Patrick Roy's out! 

"All raise your Labatts to tmurray!"


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## tmurray (Oct 18, 2018)

It is in fact the Ontario Building Code. All codes  in Canada are based on the National Building Code of Canada, similar to the California code being based on the ICC codes.


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## tmurray (Oct 18, 2018)

Pcinspector1 said:


> Oui!
> 
> So glade we got tmurray in goal since Patrick Roy's out!
> 
> "All raise your Labatts to tmurray!"


I mean...there is a French version of the national code... I don't know if the OBC is available in French or not.

Ok, I just checked...the French website says it's only available in English, so no. No French OBC.

As of yesterday you can also raise your cannabis. It is now legal in all of Canada for recreational use.


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## tmurray (Oct 18, 2018)

For those interested in the OBC: https://www.ontario.ca/laws/regulation/120332/v16


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## Pcinspector1 (Oct 18, 2018)

Boy's if you got em....lite em! 

Don't smoke and drive!


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## Inspector Gadget (Mar 5, 2020)

alayan said:


> Hello everyone,
> I'm taking my first OBC course, and I have an exercise on how to distinguish between part 9 and 3 of the OBC. For what I understand, part 9 technically applies for building having 3 storeys or less, and building area is no greater than 600 sm. But in the diagram, there is an overhang on the ground floor and a deck on the third floor which make me confused.
> 1/ Would a deck or a partial overhang contributes in building area?.
> 2/ Since there are 3 different major occupancies (1st floor- Coffe, 2nd floor- Retail, 3rd- Rooming house), What is the occupancy classification of the building?
> Thank you so much



Late to the party here. I'm in New Brunswick where we use NBC 2010. I believe our classifications are the same as yours, however.

9.10.1.3(2) indicates that any assembly space must be designed to part 3.  If the coffee shop has *any* seating, it would be an assembly use.

Once in Part 3, 3.2.2.6 says the entire building must conform to the most restrictive occupancy.  

3.2.2.65 allows for non-combustible, fire seps of 45 min; and 3.2.2.52 likewise. So as I see it - and I'm now tackling the part 3 learning curve, so tell me if I am wrong - the above building would be governed by 3.2.2.24: non-combustible construction, one-hour floor assemblies, sprinklered. 

It's actually interesting I stumbled on this question, as our office juuuuuust dealt with a potential project that dropped an assembly use occupancy so the building would land in Part 9, not Part 3.


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