# IBC vs. IRC



## lee1079

Does anyone know single family or townhouse can be designed per IBC in lieu of IRC? I have a project that includes both commercial buildings and single family/townhouses. I wonder if I could just design all per IBC.


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## cda

lee1079 said:
			
		

> Does anyone know single family or townhouse can be designed per IBC in lieu of IRC? I have a project that includes both commercial buildings and single family/townhouses. I wonder if I could just design all per IBC.


All in one building?

Or townhouses mixed with commercial in the same building


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## fatboy

Design it as an R-2............


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## lee1079

cda said:
			
		

> All in one building?Or townhouses mixed with commercial in the same building


They are on the same site but not in one building.


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## lee1079

fatboy said:
			
		

> Design it as an R-2............


Love to so I deal w/ one less code but below is what IBC says. See the exception.

101.2 Scope. The provisions of this code shall apply to the construction,

alteration, movement, enlargement, replacement,

repair, equipment, use and occupancy, location, maintenance,

removal and demolition of every building or structure or any

appurtenances connected or attached to such buildings or

structures.

*Exception: Detached one- and two-family dwellings and*

*multiple single-family dwellings (townhouses) not more*

*than three stories above grade plane in height with a separate*

*means of egress and their accessory structures shall*

*comply with the International Residential Code.*


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## cda

lee1079 said:
			
		

> They are on the same site but not in one building.


More than likely with this scenario, the ahj will not allow Ibc to used for entire project


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## mtlogcabin

Ask the Local AHJ if you can use the IBC under R104.11 alternate design and methods. I have allowed it and the engineers designed a less expensive building not using the prescriptive methods in the IRC.

The word shall should be changed to may in the exception.

Is an exception a requirement or an option?


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## cda

Option ........


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## Francis Vineyard

As small as it may be add a 4th story.


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## khsmith55

I’m with Fatboy, if more than 2 dwelling units call it an R-2. Since the definition of a Townhome requires a “vertical” line (assumed property line...) between the units,  from the foundation to the roof may be tweek the design to create an “offset” between the units so they would clearly not be a Townhome.


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## rogerpa

*2012 IRC*

*R104.11 Alternative materials, design and methods of construction and equipment.  * 

The provisions of this code are not intended to prevent the  installation of any material or to prohibit any design or method of  construction not specifically prescribed by this code, provided that any  such alternative has been _approved._ An alternative material, design or method of construction shall be _approved_ where the _building official_  finds that the proposed design is satisfactory and complies with the  intent of the provisions of this code, and that the material, method or  work offered is, for the purpose intended, at least the equivalent of  that prescribed in this code. *Compliance with the specific  performance-based provisions of the International Codes in lieu of  specific requirements of this code shall also be permitted as an  alternate. *

*2015 adds *"Where the alternative material, design or method of construction is not approved, the building official shall respond in writing, stating the reasons why the alternative was not approved."


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## fatboy

I believe the Exception is an option, not a requirement, and rogerpa's post above clears it as an option.


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## JBI

If Texas has adopted a newer version of the IRC that includes mandatory sprinklers then there is little difference between the IRC and IBC for Townhouses.


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## cda

JBI said:
			
		

> If Texas has adopted a newer version of the IRC that includes mandatory sprinklers then there is little difference between the IRC and IBC for Townhouses.


Whale, the problem in the great State of Texas is that the ""pol I tic  anns"" outlawed fire sprinklers in homes a few legislative sessions ago. Unless a city had a pre existing fire sprinkler ordinance in place.

Since then the legislative have had higher problems to deal with, should police officers not shoot animals , etc ???


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## JBI

Based on cda's response, the difference between IRC and IBC is that IBC requires sprinklers for all R occupancies and under the IBC ALL homes are R occupancies.


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## dill bill

Can I bump this old thread? 

I'm working on an existing commercial warehouse building with several full length bays. We are doing two single family units and a restaurant, all side by side separated by masonry walls, just three rectangles. We can do a full fire wall between the restaurant and adjacent SFR. The client would also like to permit the residences first and separately if the AHJ will let us. 

So the situation is similar to the original above, except for it is in one building. Except per the definition of fire walls, these are technically separate buildings, with property lines between them too. The AHJ is very unexperienced and unreliable so no help there. She asked me if I was permitting them through IBC or IRC; at the time it sounded like she didn't know or care herself. I'd like to have a foot to stand on in either case though. Nothing will change in the design in either case, the buildings will be fully sprinklered, etc. 2012 code if it matters.


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## Joe.B

My understanding is that a designer needs to decide up front which code they are designing too, and stick with that throughout. The plan reviewer needs to know which code you're using so they can plan-check accordingly. The residential code is limited in scope, the building code is all-inclusive. I.e. anything designed by residential could have been designed by building code, but not the other way around. 

The problem I have experienced is when a designer is most familiar with CBC (IBC based) but then they want to use a CRC (IRC based) exemption. For example, a second unit designed under CBC, but trying to use the CRC fire sprinkler exemption. The CBC has no exemptions for fire sprinklers for new residential, and the associated wall rating requirements are different in each code. In this example there was only a 2 foot separation between two buildings and they based their wall rating off of CBC which assumes sprinklers are included. The CRC does not assume sprinklers so there are higher wall ratings required when using CRC.


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## Mark K

You can always design any building using the IBC.  Remember the IBC applies when you are dealing with multifamily residential projects.

The IRC was developed with the intent to address a limited subset of residential buildings in hopes of making it easier for individuals to understand, who were not architects or engineers.  In my experience the IRC provisions are usually more opaque.

In my experience when structural engineers are involved with residential projects, that may allow the use of the IRC, they will use the structural provisions in the IBC  The IBC, in general, allows you more flexibility in complying with the code.


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## Beniah Naylor

dill bill said:


> So the situation is similar to the original above, except for it is in one building. Except per the definition of fire walls, these are technically separate buildings, with property lines between them too.


There is a definition of "fire wall" in the IBC, but not in the IRC. It could be argued that if you are using a "fire wall" to separate occupancies, you are building something that is not in the IRC. This kind of construction is traditionally attempted under the IBC.

Using the IBC for this is safe and would be accepted almost anywhere. I'm not saying that you absolutely can't use the IRC, but this scenario is not what the IRC was intended for - if I was the AHJ you _might_ be able to convince me that the IRC can technically be used.


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## Mark K

Under which code provision can you say that the IRC can be used when you recognize that the IRC was not intended to address that condition?  If there is no code basis you are likely practicing architecture or engineering without a license.


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## Jay Smith

It seems like you could just design each house with exterior walls that meet the IRC requirements where fire separation distance is zero.


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## e hilton

Does local zoning allow sfr and restaurant in the same block?


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## ICE

Mark K said:


> you are likely practicing architecture or engineering without a license.


I did that for an entire career....I was known to practice medicine without a license.  Had anyone inquired I would have been comfortable performing marriages.  There was a time when I was a licensed hot air balloon instructor and I've never been near one.. Vegas Paul was a licensed nuclear reactor operator ...and he was in one.

You are quick to try shutting down reasonable people with the license bugaboo.  How about sharing some of that engineer’s knowledge instead of pointing out   that obvious, satisfactory options are engineering.

Here’s a tip for all of the engineers.  Engineered once is engineered forever. We don’t need a license to use the engineered solution forever.


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## Mark K

"license bugaboo" is an interesting term to be used by an individual employed to enforce the laws.


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## ICE

Mark K said:


> "license bugaboo" is an interesting term to be used by an individual employed to enforce the laws.


Thanks Mark


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## Beniah Naylor

Mark K said:


> Under which code provision can you say that the IRC can be used when you recognize that the IRC was not intended to address that condition?  If there is no code basis you are likely practicing architecture or engineering without a license.


I am on the enforcement side, and I have a duty to protect the rights of the people I serve. In my world, it's not so much about what the code says you _can_ do, it's about what is says you _can't _do.

If the code says you can't do something, you can't. If it doesn't say you can't, that means you can whether there is "a code that says you can" or not.

I made a somewhat unmotivated attempt to find a code section that says you can't, and I was unable to do so... not that it isn't there somewhere... I just have no motivation to find it today since this isn't my jurisdiction...


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## tbz

From a code standpoint, if the 3 single family residences are on their own lot, are they not technically townhouses, if the only structure on each lot is a single-family home and under 3 stories?  

If zoning allows both to be there, then why not?

Fire walls / separation what else they need?

IF the fire separation requirements are met between the last home and the bakery next door, is it really the same building, or is it not each building is their own, just sharing firewalls on the lot line?

As to the sprinkler systems, I haven't a clue, but I would assume each LOT & Building has to be a separate self-contained system.

I could be wrong, but can sprinkler systems cross property lines?

And in TN, are IRC built structures required to have sprinklers?

But, the design professional should have spelled all this out on the drawings, as I would assume, each property needs its own set of drawings for the permit application.

Then again I could be totally off base here.

Tom


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## Mark K

Beniah Naylor said:


> I am on the enforcement side, and I have a duty to protect the rights of the people I serve. In my world, it's not so much about what the code says you _can_ do, it's about what is says you _can't _do.
> 
> If the code says you can't do something, you can't. If it doesn't say you can't, that means you can whether there is "a code that says you can" or not.
> 
> I made a somewhat unmotivated attempt to find a code section that says you can't, and I was unable to do so... not that it isn't there somewhere... I just have no motivation to find it today since this isn't my jurisdiction...


Enforcement has to do with enforcing the limited rules that society has adopted to constrain the rights of the members of society.  Being on the enforcement side does not empower an individual to require what he believes should be.  Only a properly empowered legislative body can adopt laws, which include building regulations.  A state can delegate an admirative body the ability to adopt regulations, such as building codes, but only if the legislature has properly constraint the authority of that administrative body.  In all cases the legislative body or an administrative agency must follow certain rules in adopting regulations.  This is due process.

In our system of laws there is NO place for an individual unilaterally empowered to impose requirements on individuals.  To do so would bypass the legislative process and would empower an autocrat.  

In many parts of the country the immunity that building officials have is based on the "public duty doctrine" which states that their duty is to the public as a whole and not to individual members of the  public.  This means that they can only enforce the adopted laws.  Building officials are not there to protect individuals from their stupidity.

Building officials are empowered to enforce the properly adopted building regulations.  If you cannot quote a building regulation the property owner can do what he or she wishes.  Yes some individuals will do dumb things but that is their right.


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## Joe.B

Mark K said:


> Enforcement has to do with enforcing the limited rules that society has adopted to constrain the rights of the members of society.  Being on the enforcement side does not empower an individual to require what he believes should be.  Only a properly empowered legislative body can adopt laws, which include building regulations.  A state can delegate an admirative body the ability to adopt regulations, such as building codes, but only if the legislature has properly constraint the authority of that administrative body.  In all cases the legislative body or an administrative agency must follow certain rules in adopting regulations.  This is due process.
> 
> In our system of laws there is NO place for an individual unilaterally empowered to impose requirements on individuals.  To do so would bypass the legislative process and would empower an autocrat.
> 
> In many parts of the country the immunity that building officials have is based on the "public duty doctrine" which states that their duty is to the public as a whole and not to individual members of the  public.  This means that they can only enforce the adopted laws.  Building officials are not there to protect individuals from their stupidity.
> 
> Building officials are empowered to enforce the properly adopted building regulations.  If you cannot quote a building regulation the property owner can do what he or she wishes.  Yes some individuals will do dumb things but that is their right.


I don't think anybody would dispute your statement. I think what rubs everybody the wrong way is you implication that all us code officials are just doing whatever we think is right. You may have had some negative experiences with specific individuals in your own life, but please keep in mind that we are not all automatically bad people just because of our profession. Your comments and how you speak to a community like this is really off-putting and it's unfortunate because you share some good information and it's a good perspective for us to hear. It's really hard to actually "hear" you though because all of your comments are colored with such negativity and resentment. Honestly I usually just tune you out.


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## Mark K

I recognize that probably most building department personnel understand the limits on what they can do, but I do not hear building department individuals push back on those individuals who abuse their position.    When I hear no push back is it wrong for me to assume that these abuses are tolerated?  Does this lack of pushback embolden those individuals who are inclined to abuse their position?


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## ICE

Mark K said:


> "license bugaboo" is an interesting term to be used by an individual employed to enforce the laws.


Well then Mark K now that I am interesting and we are friends, I have posted a reply at the thread Average Day.....I figured that we are way too far off track here and lee1079 deserves better.


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## Joe.B

Mark K said:


> I recognize that probably most building department personnel understand the limits on what they can do, but I do not hear building department individuals push back on those individuals who abuse their position.    When I hear no push back is it wrong for me to assume that these abuses are tolerated?  Does this lack of pushback embolden those individuals who are inclined to abuse their position?


Personally I just choose to ignore bad apples when I can. I am fortunate enough to be in a very small jurisdiction so I have the opportunity to make sure that anybody I work with stays well within their authority. What happens in the next town over is not under my authority and none of my business. When I hear the stories that contractors tell me I shake my head and share my condolences, but I'm not going to stick my neck out and go beyond my jurisdiction to try to affect change. On a forum like this it's really none of my business so I just ignore a lot, and I'll chime in if I feel like there's something productive I can add. That's the only reason I even addressed you directly, I appreciate your knowledge and experience and I'm hoping that maybe you would be willing to hear some constructive criticism to help better the discourse.


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## Mark K

Design professionals do not have the luxury of ignoring a bad apple when the bad apple is plan checking or inspecting their project.

The need to deal with constructive criticism goes both ways.


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## steveray

Mark K said:


> "license bugaboo" is an interesting term to be used by an individual employed to enforce the laws.


In ICE's defense, I don't think he is employed to do anything anymore....

BOT....I think I could allow IBC, but it would likely be way cheaper to build it IRC....At least in Connecticut....


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## Joe.B

Mark K said:


> Design professionals do not have the luxury of ignoring a bad apple when the bad apple is plan checking or inspecting their project.
> 
> The need to deal with constructive criticism goes both ways.


I'm not suggesting you change anything you do in your business dealings, obviously you have a vested interest in your interactions with clients and officials. Totally get that, and none of my business. I was suggesting that you leave it at the door when you come here. If you have some constructive criticism for me, I'm happy to hear it.


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## redeyedfly

tbz said:


> From a code standpoint, if the 3 single family residences are on their own lot, are they not technically townhouses, if the only structure on each lot is a single-family home and under 3 stories?



No.  Townhouses are typically on their own lot.  Part of the definition of a townhouse is that there are no vertical offsets at the property line so that each unit can be on its own lot, with an offset they would be condos (or apartments).  The main difference between a condo and a townhouse is that you can describe a townhouse plot with lines on the ground, in a condo you can define an area above ground.


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## tbz

redeyedfly said:


> No.  Townhouses are typically on their own lot.  Part of the definition of a townhouse is that there are no vertical offsets at the property line so that each unit can be on its own lot, with an offset they would be condos (or apartments).  The main difference between a condo and a townhouse is that you can describe a townhouse plot with lines on the ground, in a condo you can define an area above ground.


Redeyedfly,

Each of the single family homes are on their own lot, not overlapping, just sharing the common lot line attached at that point.

Is that not a townhouse?  

From my understanding of the OP, each is on its own lot, thus a townhome and IRC could be used.  

Not sure what I am missing, but could be a lot....


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## steveray

tbz said:


> Not sure what I am missing, but could be a lot....


Property line.....a lot....Get it?


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## redeyedfly

tbz said:


> Redeyedfly,
> 
> Each of the single family homes are on their own lot, not overlapping, just sharing the common lot line attached at that point.
> 
> Is that not a townhouse?
> 
> From my understanding of the OP, each is on its own lot, thus a townhome and IRC could be used.
> 
> Not sure what I am missing, but could be a lot....


Maybe I'm misreading your post.  Townhouses are technically single family attached.  So I would say they are a subset of single family with their own specific rules because of zero FSD.  We might be saying the same thing other than they are technically townhouses each on their own lot.


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## dill bill

Thanks redeye, steve, and tbz for getting this back on track. 

In any case we will most likely meet the requirements for both the IRC and IBC because of the peculiarities of this project. The question is, is it just semantics whether these are townhomes or R3 at that point? The confusion comes because I've never worked on or seen townhomes located next to a restaurant in what visually appears like the same building, even though by the language of the code they are separate.


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## tbz

Walk down any street in Manhattan, not avenue, a street and you will find it everywhere.

As noted, the design professional needs to see what the best fit is, and specify which code to follow.

Each has their plus's and minus's, without fully looking at the entire plan, unless there is something big and glaring that for that specific reason you want to use the IRC over the IBC, it might be simpler to just do it all under the IBC and as you said semantics.

But there are reasons for the IRC that benefit the home builder, and that type of construction.  IF the benefits aren't there, then does it matter no.


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## redeyedfly

dill bill said:


> The confusion comes because I've never worked on or seen townhomes located next to a restaurant in what visually appears like the same building, even though by the language of the code they are separate.


That part is pretty weird.


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## redeyedfly

tbz said:


> Each has their plus's and minus's, without fully looking at the entire plan, unless there is something big and glaring that for that specific reason you want to use the IRC over the IBC, it might be simpler to just do it all under the IBC and as you said semantics.


Depending on the local code amendments, sprinklers would be a big reason to not go IBC.  Far less prescriptive paths and more reliance on engineering and RDPs is another.


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## Mark K

Whether the two adjacent buildings visually appear to be the same building is not a building code issue.  What matters is whether they are physically separate and individually comply with the building code.

If the building complies with the IBC what the IRC says is irrelevant.  If the IRC applies to the particular building and the building does comply with the IRC, you do not need to determine that the building complies with the IBC.  If the IRC applies to a  building but part of the building does not comply with the IRC the non-compliance


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