Mueller Building engineered to IBC 2012 - County requires IRC 2015 dillema

[finn]

Believe it or not, folks in large portions of the country get along just fine without code enforcement and onerous building and utility code restrictions.

I can show you a dozen or more buildings that have collapsed over the past five years.

Some were code compliant, but most weren’t.

 

[gsmith22]

That is very good to know about the foundation requirements, I will look into that some more. I suppose the building department / inspector (seems like a one man operation here) will take issue with it, if my proposed 6" slab (4000 PSI w/ wire mesh), and 1' x 2' deep footers aren't satisfactory? I didn't notice any column base reactions on the preliminary drawings that Mueller sent me.

I would need an exposure category "c" where I live (due to open fields around me on all sides), which both building types cover.

i see this older thread was resurrected and figured i would chime in for anyone reading this later on. With respect to building codes, understand that the IRC is a simplified, perscriptive (rules based) version of the IBC made specifically for a contractor to build a building without engineering. In effect, to make the IRC, they take the parts of the IBC related to single family or multifamily less than three stories (so IBC use groups R5 plus parts of R2 and R3) and make a specific code. Then they reorganize the information into chapters that generally follow the order of construction (ch 3 planning, ch 4 foundations, ch 5 floors, ch 6 walls, etc.). Furthermore the percriptive rules allow you to eliminate engineering design. Follow the rules as written and you don't need engineering (might need architect though) but options are limited by the pre-engineered choices in the IRC. At any time, you can decide to ignore the percriptive rules based format of the IRC (chapters 4 and onward) and use IRC chapter 3 which allows you to design (with engineering) per the IBC. Read IRC section 301.1 and it lays this out. keep in mind the IBC is a performance based code meaning that it doesn't give you completed designs to choose from, just the limiting parameters and you can come up with any design you want that fits within those limiting parameters. IRC just gives you 1 or several options to choose that are known to work for use groups R5 and parts of R2 and R3. If your metal building met the IBC, it defiantely met any IRC requirement.

In my experience, I can't imagine a metal building meeting IBC 2012 and not automatically meeting IBC 2015 or 2018. Loads just don't change that much (if at all) from code to code.

On the reply I replied to, the poster brings up a good point to remember. Foundations aren't included in these things and likely need to be designed/permitted seperately from the metal building. Metal buildings are light and as your wind loads go up, the hold down requirements for your foundation also increase. I've seen light metal buildings with huge spread footings (far more than needed for downward gravity load bearing on soil) simply to provide a downward load to counteract wind uplift in the columns. I would personally not go crazy with the wind design for anything more than required by the windspeed in your zip code to make sure you don't end up spending all the money you saved on the metal building in the foundations as boat anchors. A very nice site for design loads based on your address is: https://hazards.atcouncil.org/. it takes ASCE 7 (where loads are pulled from for IBC/IRC) and digitized the loading maps.

 

[quakerj]

What did you end up doing?

I went with the "custom" building that let me specify my own overhead door opening. Otherwise the building was left the same (bare bones) as the standard kit.

The sales rep explained to me that just because it's engineered to 115mph wind (my local code requirement) doesn't mean it's somehow an inferior building structurally compared to the standard kit rated at 140mph -- he said the only reason people need that rating is in hurricane-prone areas or areas whose codes require that high a rating. He sent me preliminary plans for both (standard 140mph kit vs custom 115mph) before I made my decision and both looked pretty much identical in terms of column placement, member sizes, etc, other than the OH door frame size and column placement adjacent to the door.

 

[quakerj]

On the reply I replied to, the poster brings up a good point to remember. Foundations aren't included in these things and likely need to be designed/permitted seperately from the metal building. Metal buildings are light and as your wind loads go up, the hold down requirements for your foundation also increase. I've seen light metal buildings with huge spread footings (far more than needed for downward gravity load bearing on soil) simply to provide a downward load to counteract wind uplift in the columns. I would personally not go crazy with the wind design for anything more than required by the windspeed in your zip code to make sure you don't end up spending all the money you saved on the metal building in the foundations as boat anchors. A very nice site for design loads based on your address is: https://hazards.atcouncil.org/. it takes ASCE 7 (where loads are pulled from for IBC/IRC) and digitized the loading maps.

WNYFlyer touched on this also, and I really appreciate your guys' input. I'm glad I didn't go with the 140mph wind speed rating as it would have likely made the foundation prohibitively expensive.

I learned this throughout the planning process that steel buildings are a very different animal than typical "residential" detached garage construction in this area. Nearly everyone builds pole barns here, the minority do stick built. The county issued me a permit without any engineered foundation plans, they simply said 12" wide x 2' deep (for frost line) foundation, 1 run each of #4 rebar top & bottom is what they expect to see at inspection, but also said I'm free to go beyond that. I know their basic requirement is not sufficient.

I work in structural steel fabrication, and have a good relationship with a structural engineer we work with. I ran my building plans by him, and he suggested 16"W x 2' deep perimeter footing (with 2 runs each of #4 rebar top & bottom), and a 3' x 3' x 2'D footing underneath the sidewall (rigid frame) columns with a #4 rebar mat (8" OC) tied into the bottom foundation rebar. He said to go the extra mile I could add a hairpin rebar around the rigid column anchor bolt setting, to tie into the slab. Obviously this is off the cuff and he won't stamp anything unless I officially hire him, but I trust his judgement. Does anything sound out of whack?

My first concrete guy flaked out on me (I guess the steel building details scared him) and pushed my schedule out a month, but I have a concrete contractor that does both residential and commercial meeting with me on Sunday. Any input on foundation / slab design is welcome!

 

[billconner]

understand that the IRC is a simplified, perscriptive (rules based) version of the IBC made specifically for a contractor to build a building without engineering. In effect, to make the IRC, they take the parts of the IBC

I believe the IRC is based more on the CABO One and Two Family Dwelling Code than excerpts from the IBC. The first edition of the IBC (2000) was based on the three legacy codes and BCMC reports.

 

[gsmith22]

I believe the IRC is based more on the CABO One and Two Family Dwelling Code than excerpts from the IBC. The first edition of the IBC (2000) was based on the three legacy codes and BCMC reports.

Read the preface to any of the old CABO codes and you will find out it was a compliation of the building codes produced by the three major code bodies at the time - BOCA, Standard Building Code, and Uniform Building Code with parts taken specifically for residential use. BOCA, SBC, and UBC were the precursors to IBC. Those three code bodies merged around 1999-2000 and became ICC which produces the IBC. The IBC took the good parts of each code body document and combined them so it is/was a compliation of BOCA, SBC, and UBC. As an example, BOCA had good snow loading, SBC was ahead on wind loading, and UBC was ahead on seismic loading simply because of the areas of the country those codes were primarily focused on. IBC included all of that and continues to. I'm sure the first several additions to IRC looked very similar to CABO so it wasn't a total rewrite but as changes are made in IBC, they get reflected in IRC. There is a shared history between all of the codes. The IRC generally isn't allowing things that don't also meet the requirements of the IBC and the fact that you can do an engerineered design for parts or all of a residential structure at any time (per IRC Ch 3) shows how they are absolutely interrelated.

 

[gsmith22]

I learned this throughout the planning process that steel buildings are a very different animal than typical "residential" detached garage construction in this area. Nearly everyone builds pole barns here, the minority do stick built. The county issued me a permit without any engineered foundation plans, they simply said 12" wide x 2' deep (for frost line) foundation, 1 run each of #4 rebar top & bottom is what they expect to see at inspection, but also said I'm free to go beyond that. I know their basic requirement is not sufficient.

I work in structural steel fabrication, and have a good relationship with a structural engineer we work with. I ran my building plans by him, and he suggested 16"W x 2' deep perimeter footing (with 2 runs each of #4 rebar top & bottom), and a 3' x 3' x 2'D footing underneath the sidewall (rigid frame) columns with a #4 rebar mat (8" OC) tied into the bottom foundation rebar. He said to go the extra mile I could add a hairpin rebar around the rigid column anchor bolt setting, to tie into the slab. Obviously this is off the cuff and he won't stamp anything unless I officially hire him, but I trust his judgement. Does anything sound out of whack?

Go with the engineer's suggestion - its not that onerous and far better than the county's min. If anything, the column footings are most important but the perimeter footing is providing frost protection for the slab edge so keep that in mind. The hairpin is likely to try distribute lateral shear into the slab on grade -the steel frame trying to spread out as it is loaded. Its a common detail and if you can include it I would. One story rigid steel frames like to behave as an arch so you get an outward thrust load at each column base. The hairpin ties the column base to the slab. Could continue rebar across the slab to column at other side attempting to create a tied arch which is much stronger overall than the rigid frame but that is certainly not necessary to make your steel frame work as intended (unless of course the steel manufacturer requires something like that in their plans).

 

[billconner]

I'm sure the first several additions to IRC looked very similar to CABO

So we agree.

Don't overlook the BCMC work, which was a collaboration of the three legacy code organizations and the NFPA, and was used as the basis for many parts of the first edition of the IBC.

 

[gsmith22]

So we agree.

Don't overlook the BCMC work, which was a collaboration of the three legacy code organizations and the NFPA, and was used as the basis for many parts of the first edition of the IBC.

i don't think we disagree but my broader point when I initially responded was the IRC (even when it was CABO) is really a distillation of the primary performance based IBC commercial code (as BOCA, SBC, and UBC were for CABO) into a perscriptive code specifically for R5 and parts of R2 and R3 use groups. The IRC was not crafted out of thin air with no resmeblance to IBC. You could always use IBC to design a residence but it is vastly simplier to use IRC.

 

[billconner]

Do they both provide for a minimally safe building? Yes. Same physical principals? Yes. I just don't find the IRC derived from IBC, and very much from the CABO OTFDC, which was (and as IRC is) much more shaped by homebuilders compared to the IBC being shaped by engineers. Just reading chaper titles of IRC, they are very close to OTFDC.