Residential vs Commercial Code?
Residential vs Commercial Code?
(OP)
My coworker and I have had a disagreement as of late. It revolves around when you are allowed to use the residential code and when you are allowed to use the commercial code. I have always said that the residential code is to be used for 1 and 2 family dwellings (hence the name). He says that if the project is residential then you can ignore the commercial code and go straight to the residential. The project in question is a 3 family dwelling with an issue regarding calculation of seismic loads. Does anyone have any opinion on the matter? When are you allowed to use the residential code vs the commercial code?






RE: Residential vs Commercial Code?
Apartments and condominiums are considered commercial construction and would fall under the main building code. Further, in some instances, the residential code refers you back to the primary building code.
RE: Residential vs Commercial Code?
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Residential vs Commercial Code?
In my opinion, the IRC just allows the contractor and owner to save money by scrimping on the structure.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Residential vs Commercial Code?
RE: Residential vs Commercial Code?
RE: Residential vs Commercial Code?
RE: Residential vs Commercial Code?
In 10 years of doing residences under IBC guidelines, I have never had a design rejected by any building department for not using the IRC. I have always found the IBC more stringent.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Residential vs Commercial Code?
Thanks for the info.
RE: Residential vs Commercial Code?
RE: Residential vs Commercial Code?
EIT
www.HowToEngineer.com
RE: Residential vs Commercial Code?
The project is an mess and is a discussion for another time. The reference project is an existing 3 story building that the owner would like to add two additional stories to. We were discussing the amount of additional lateral load that would be added to the existing structure due to the new structure above. His only defense was that the project is residential and not commercial therefore no seismic loading required. He eventually folded, but only after I told him that the first floor is retail space (something he didn't know when I presented the project to him for his opinion). In my eyes, we are now talking about a 5 story building..... what are the odds that only two families would occupy a 5 story building.
No harm done, just a little discussion and I was wondering when IBC takes over from IRC.
RE: Residential vs Commercial Code?
Well, FWIW we seem to use the IBC for all cases, same as others have noted. Actually, in some 'higher end' villages they wanted to see seismic calcs (maybe I'm recalling this incorrectly) even though they don't usually 'control' around here.
EIT
www.HowToEngineer.com
RE: Residential vs Commercial Code?
1) It does allow the IBC to be used see section R301.1.3 “...Engineered design in accordance with the International Building Code is permitted for all buildings and structures, and parts thereof, included in the scope of this code.”
2) It does require the building to be designed for seismic see “R301.1 Design. Buildings and structures, and all parts thereof, shall be constructed to safely support all loads, including dead loads, live loads, roof loads, flood loads, snow loads, wind loads and seismic loads as prescribed by this code...”
3) The maximum height is three stories see “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 multiple single-family dwellings (townhouses) not more than three stories in height with a separate means of egress and their accessory structures.”
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Residential vs Commercial Code?
In WI where I practice, is is very clear that anything not a one or two (other than agricultural) is a commercial structure. The language of the code will tell you if it applies to the building or not. Your state may vary though.
MAP
RE: Residential vs Commercial Code?
Having said that, I think an engineer should have the prerogative to appeal to the IRC even if it is less stringent. But this is not really "design", it is just "selection" which is why it can theoretically be done by a contractor without an engineer.
I'm sure that the IRC is enforced by CBO's for many of the other non-structural sections.
RE: Residential vs Commercial Code?
We are now looking at a project that is a 4 unit townhouse joined together by common walls. He is saying that the IRC can be followed for townhouses and he does not have to follow the provisions of the IBC. This is the definition he is referencing:
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.
Now I read this as applying to one and two family townhouses. He is saying that this applies to all townhouses no matter how large the project is. What do others think?
RE: Residential vs Commercial Code?
As far as I am concerned, the IRC is aplicable only to one and two story SFR's, not to multiple structures with common walls, or over two stories.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Residential vs Commercial Code?
RE: Residential vs Commercial Code?
"A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or public way on at least two sides."
So, you can't have a two unit townhouse using the IRC definition.
RE: Residential vs Commercial Code?
BA
RE: Residential vs Commercial Code?
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Residential vs Commercial Code?
One wonders why the snow load should vary according to the type of building upon which it is falling.
BA
RE: Residential vs Commercial Code?
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com