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What is this building?

B

bill1952

SAWHORSE
Joined
Aug 12, 2021
Messages
2,592
Location
Clayton NY
Is an accessory structure to a one family dwelling still an IRC building if using R301.1.3 Engineered design.

"Where a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for buildings and structures, and parts thereof, included in the scope of this code."

I thought yes except the company furnishing the post frame design, materials, and sealed drawings says you can't design post frame under IRC and wants to know what type of IBC building it is (S1 or S2? not U since its over 1000 sf).
 
It is an engineered building using the IBC design requirements. It is an accessory structure to a single family residential dwelling unit and therefore not limited in size under the IRC.

If you want to properly classify the use of the building under the IBC it would be an S-2 which allows a non sprinkled type v construction to be a maximum of 13,500 sg ft
 
Does it fit the definition?

R101.2 Scope. The provisions of the International Residential
Code for One- and Two-family Dwellings shall apply to
the construction, alteration, movement, enlargement,
replacement, repair, equipment, use and occupancy, location,
removal and demolition of detached one- and two-family
dwellings and townhouses not more than three stories above
grade plane in height with a separate means of egress and
their accessory structures not more than three stories above
grade plane in height

[RB] ACCESSORY STRUCTURE. A structure that is
accessory to and incidental to that of the dwelling(s) and that
is located on the same lot.
 
Just seems odd to use IBC to design the the structure including foundation, walls, and roof of a building - basically all IBC - and still it's an IRC building.
 
The design of the structure is IBC because the IRC does not have prescriptive requirements for pole buildings.
The use falls under the IRC because it is accessory to the dwelling unit.
If the building is being used for anything else then the whole thing could come under the IBC and all the other codes that may apply to the use
 
Private garages are in IBC. Just not clear to me when it's an accessory building used to store cars and when it's either a type U building (if 1000 sf or less) private garage or type S2 low hazard storage. It would be the same design.
 
The phrase "accepted engineering practice" is not clear and from a code perspective meaningless. Accepted by who? Am I required to comply with whatever the building official says? When I see this phrase I look to the provisions in the IBC.

Once you have used the IBC structural provisions what prevents you from using the IBC for other parts of the design?
 
I'll go whichever way the building dept prefers. :)

I'd really like to stick build using pure IRC prescriptive requirements except with rough sawn local lumber instead of grade stamped. Footing and stem wall more work but I like the basic carpentry and look of rough sawn, and it's price at a 1/3 or 1/4 of graded lumber.

Thank you for sharing the ideas.
 
mtlogcabin said:
The design of the structure is IBC because the IRC does not have prescriptive requirements for pole buildings.
The use falls under the IRC because it is accessory to the dwelling unit.
If the building is being used for anything else then the whole thing could come under the IBC and all the other codes that may apply to the use
Click to expand...
So what section in the IBC has prescriptive requirements for a pole building?
 
There are not prescriptive requirements for post frame construction, just like there are not for steel frame or reinforced concrete or sips or other systems. From my viewpoint, there are prescriptive requirements for platform and balloon framed and masonry 1 and 2 family dwellings, with a few minor variations. (I may be overlooking some other system - just highlights.) Otherwise the design has to be engineered by a registered design professional, which is intended to assure "accepted engineered practice" reliably. In the 2021 IBC, section 1807.3 Embedded Posts and Poles is the beginning for designing a post frame building.

The company that will furnish me the material package will also furnish sealed drawings for permit and building.
 
I should add, I think there are some jurisdictions, semingly in rural agricultural areas, which have their own prescriptive standards for post frame aka pole barns.
 
The IBC applies to all occupancies, including one- and two-family dwellings and townhouses that are not within the scope of the IRC.
The IRC is a prescriptive code
The IBC is a design/performance based code

Chapter 16 Structural Design. Chapter 16 prescribes minimum structural loading requirements for use in the design and construction of buildings and structural components. It includes minimum design loads, assignment of risk categories and permitted design methodologies. Standards are provided for minimum design loads (live, dead, snow, wind, rain, flood, ice and earthquake as well as the required load combinations). The application of these loads and adherence to the serviceability criteria will enhance the protection of life and property. The chapter references and relies on many nationally recognized design standards. A key standard is the American Society of Civil Engineers’ Minimum Design Loads for Buildings and Other Structures (ASCE 7). Structural design must address the conditions of the site and location. Therefore, maps are provided of rainfall, seismic, snow and wind criteria in different regions.
 
mtlogcabin - I understand your points but isn't a 1 or 2 family dwelling that uses just one or a few engineered pieces - a roof truss or a shallow frost protected foundation for instance, neither of which seem to have prescriptive designs - still an IRC building, and I can still use the prescriptive designs for other parts? Kind of what R302.1.3 says?

When does a building as scoped in R101.2 have to be IBC?

And I have to wonder if meeting all the requirements of IRC assures it would meet the IBC requirements. I'm sure I many instances IRC exceeds IBC, the nature of prescriptive designs.
 
When you can not or do not meet the prescriptive requirements or exceed the design limitations of the IRC then a DP will use the IBC to design a code compliant building. Usually it is just for a specific portion of the residential structure such as an 18 ft tall wall or a foundation because of terrible soils
A pole barn or post and beam or log home construction are not typical residential construction and therefore they are not structurally addressed in the IRC However everything else in the IRC would be used for code compliance such ventilation, lighting and exit requirements.

R106.1 Submittal documents.
Submittal documents consisting of construction documents, and other data shall be submitted in two or more sets with each application for a permit. The construction documents shall be prepared by a registered design professional where required by the statutes of the jurisdiction in which the project is to be constructed. Where special conditions exist, the building official is authorized to require additional construction documents to be prepared by a registered design professional.
 
bill1952 said:
When does a building as scoped in R101.2 have to be IBC?
Click to expand...
That's a easy answer:

[A] 101.2 Scope. The provisions of this code shall apply to
the construction, alteration, relocation, 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 not
more than three stories above grade plane in height, shall
comply with the International Residential Code.
 
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