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.

 

[cda]

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

 

[fatboy]

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

 

[lee1079]

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

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

 

[lee1079]

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.

 

[cda]

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

 

[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?

 

[cda]

Option ........

 

[Francis Vineyard]

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

 

[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.

 

[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."

 

[fatboy]

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

 

[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.

 

[cda]

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 ???

 

[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.

 

[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.

 

[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.

 

[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.

 

[BN4537]

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.

 

[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.

 

[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.

 

[e hilton]

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

 

[ICE]

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.

 

[Mark K]

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