KZQuixote
Sawhorse
I don't think so! He's just asking the ICC, engineer or not, to explain their less than clear code section.GHRoberts said:
Are you suggesting that only an engineer can explain the building code?
Bill
-
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Lateral load connectors
- Thread starter NH09
- Start date
Are you suggesting that only an engineer can explain the building code?
Bill
Yankee
Registered User
I expect this is the part that ICC finds unclear ~
"If it cannot, I would guess that two lateral load connectors would not be enough to support the ledger - what determines the addtional fastening neccesary? and would any other fastener (hilti pin for example) meet the lateral load connector requirement?"
I suggest leaving this out of the question and seeing if an answer is forthcoming.
"If it cannot, I would guess that two lateral load connectors would not be enough to support the ledger - what determines the addtional fastening neccesary? and would any other fastener (hilti pin for example) meet the lateral load connector requirement?"
I suggest leaving this out of the question and seeing if an answer is forthcoming.
NH09
Silver Member
I wasn't asking the ICC to practice engineering GH, but to clarify how we would determine what additional connections would be necessary when using lateral load connectors. I attempted to clarify my question and received a response:
Mr. Rangel (ICC),
Myself and other inspectors have been struggling with the new lateral load connector requirement, some inspectors are convinced they required on every deck, some say they are not needed unless an engineer has required them. From your initial answer (June) I had assumed that if the lagging requirements can be met, then no lateral load connectors would be required –simple enough. However, if the lagging requirements cannot be met can I assume that two lateral load connectors (regardless of the size of the deck) are sufficient to fasten the deck to the house? And if they are not, how would I determine the additional fastening means for the ledger? I apologize if the question is unclear, but this new requirement has been very confusing.
ANSWER: Two lateral load connectors, as depicted in Figure R502.2.2.3, are the minimum number required if this method is utilized. Additional connectors and or other fastening means, based on an engineering analysis, may be required as a result of the size of the deck.
At this point, I will do the following when presented with a deck application:
1.) Inform the applicant they must meet the lagging requirements of section R502.2.2.1, or
2.) Build a freestanding deck, or
3.) Have an engineer design their deck, and let the engineer determine if any lateral load connectors are necessary.
I really believe the ICC could have done a better job with this section.
Mr. Rangel (ICC),
Myself and other inspectors have been struggling with the new lateral load connector requirement, some inspectors are convinced they required on every deck, some say they are not needed unless an engineer has required them. From your initial answer (June) I had assumed that if the lagging requirements can be met, then no lateral load connectors would be required –simple enough. However, if the lagging requirements cannot be met can I assume that two lateral load connectors (regardless of the size of the deck) are sufficient to fasten the deck to the house? And if they are not, how would I determine the additional fastening means for the ledger? I apologize if the question is unclear, but this new requirement has been very confusing.
ANSWER: Two lateral load connectors, as depicted in Figure R502.2.2.3, are the minimum number required if this method is utilized. Additional connectors and or other fastening means, based on an engineering analysis, may be required as a result of the size of the deck.
At this point, I will do the following when presented with a deck application:
1.) Inform the applicant they must meet the lagging requirements of section R502.2.2.1, or
2.) Build a freestanding deck, or
3.) Have an engineer design their deck, and let the engineer determine if any lateral load connectors are necessary.
I really believe the ICC could have done a better job with this section.
High Desert
Gold Member
Just a point, the ICC does not write the codes...we do as members of ICC. I spoke against this code change at the Rochester hearings but it was passed anyway. The section is broken and needs to be fixed.
I never said you did.NH09 said:
What you did do was ask them a legal question. That is: What does your adaption of the ICC code as law mean? Perhaps you were asking them to practice law without the proper license.
---
If I ask my neighbor, if a 2x6 will span a certain distance. He can answer without practicing engineering because I have no expectation that he has knowledge of engineering.
If I ask the AHJ the same question. He can answer with a response based on the prescriptive code tables and not be practicing engineering. If he does any math and I expect he has the ability to do the correct math he is practicing engineering
If I answer the question, I am always practicing engineering, because I have a license.
Most professions work that way.
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High Desert
Gold Member
GHRoberts, the code is not law for ICC. They promulgate and publish the codes, which are a suggested set of construction standards. So you're saying that ICC cannot render their interpretation of any code section without either practicing law or engineering? That's absurd.
Jobsaver
Registered User
GHRoberts: Is it necessary to interrupt every thread with your diatribe about practicing engineering without a license?
Yankee
Registered User
sounds good to meNH09 said:
NH09
Silver Member
You may be overthinking this GH, I was asking the ICC to clarify a code section that has puzzled inspectors in my area since the 2009 IRC came out. If the ICC can't provide a code interpretation without practicing engineering (or law for that matter) then we are all in trouble. It sounds like the ICC rushed this code change through and the only ones benefiting are a certain deck hardware manufacturer and structural engineers.
NH09
Silver Member
You may be overthinking this GH, I was asking the ICC to clarify a code section that has puzzled inspectors in my area since the 2009 IRC came out. If the ICC can't provide a code interpretation without practicing engineering (or law for that matter) then we are all in trouble. It sounds like the ICC rushed this code change through and the only ones benefiting are a certain deck hardware manufacturer and structural engineers.
Why would your AHJ ask the jurisdiction to adopt a law that the AHJ did not understand? (Seems to be a common occurance.)NH09 said:
Overall the ICC writes prescriptions that can be used to show code compliance. Those who do not want to use the prescriptions can do engineering.
I think this deck prescription is lacking in suitability (seems to be a common view), so I would do engineering. The same engineering that I did prior to this prescription.
The only good part is that AHJs can not require engineering.
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If you want the ICC to answer questions, do not ask engineering or legal questions. You should hire a local engineer or lawyer for those questions.
Yankee
Registered User
Au contraire! AHJ may require engineering.GHRoberts said:
NH09
Silver Member
Section R106.1 authorizes the building official to require review by a registered design professional, we also have a state rsa (can't find it at the moment) that requires the design professional be licensed in New Hampshire. Anytime a project falls outside the scope of the code or there are existing conditions we cannot verify, we ask the applicant to consult an engineer. I certainly have no problem requesting an engineer review deck plans if the prescribed lagging requirement cannot be met or the deck is not freestanding - I just wanted to make sure that is what the ICC intended.
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 .
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 .
dhengr
Bronze Member
Let me offer a little insight on lateral load connectors and decks. I are a registered ingeneer and I can even stamp and sign plans in some states; but I promise not to do your ingineering for you, or to pretend that I are a bldg. inspector, although I am one, if you promise not to do any engineering (shades of GH), but you should have a good deal of engineering insight to do your job well. Finely, you have to help me out a bit with the latest code editions the exact wording of the code sections you site, the tables and drawings if that’s important to your arguement. I’ve been designing structures and foundations of all types for about 45 years, and have a pretty good handle on the intent of the codes from the structural standpoint. But, I’ve given up trying to keep up with the changes or the rate of change of the codes. IMHO the code business has become a rather large industry unto itself, the codes are becoming less and less intelligible, trying to cover every situation with more and more complexity to the point that no one can interpret them any more, and with a few exceptions there isn’t real much evidence that we are really producing better structures, we’re just adding layers of confusion. This is mostly to our detriment, because neither you nor I can any longer figure out how to understand and interpret them and do our job properly.
The house sub-fl. diaphragm must be adequately nailed to the joists, blocking and rim joist; and the rim joist must be adequately nailed to the sill plate or double top pl.; that’s what gives the rim joist the ability to take some lateral load from the deck if needs be. I think your tables will show that through bolts with washers are somewhat stronger than lag bolts (pull through vs. pull out with short screw embedment), in holding the ledger to the bldg., and neither of these fasteners should be cantilevered from the rim joist and solid sheathing through insulation board and/or siding to the ledger for proper support w.r.t. vertical deck loads. And, don’t forget proper ledger flashing. For vertical loads the lag bolts must be regularly spaced and of adequate number and size to make the ledger act as if a continuously supported shelf as it picks up deck joist loading. Lag bolts to widely spaced get overloaded and cause the ledger to act as a beam btwn. the widely spaced fasteners, not particularly desirable.
Joist hangers are primarily designed for vert. loading from the joists, but they do have some ability to resist lateral loads (shear loads parallel to the ledger) and they even have some small ability to resist tension loads down the length of the joist, just not much. The deck can see lateral loads from wind on exposed surfaces, floor structure, guard rails, and privacy walls; earthquakes where the center of mass is some distance from the bldg. and might include DL, snow load, LL as part of that mass; and 4 or 5 - 300 lb. linemen standing out at the railing and swaying back and forth in a drunken group hug, plus all the other people out on the deck dancing to the same music. Now, for the sake of the point that I am trying to make, assume two different decks: one which runs out 10' perpendicular to the bldg. and 12 or 14' along the bldg. and the center of mass is out at 5-6' from the bldg. with the linemen out at 10'; vs. a deck which runs out 18' perpendicular to the bldg. and only 10 or 12' along the bldg. Any of these potential lateral loadings is trying to rip the deck away from the rim joist/fl. system; causing tension at one edge (corner) of the deck and compression into the bldg. at the other deck corner. Given the nature of the beast, the tension loads will be concentrated in the outermost 2 or 4 joists, tending to rip them away from the buidling. I submit that I can most likely make the 10x12 deck work without any special tension hardware, but the 18x12 deck will most likely need special tension hardware and bracing out at its far end. I would probably attach this hardware to the 1st or 2nd interior joist on each edge of the deck since I don’t know which direction the lat. load might be applied. These same connector sets should probably be attached to interior joist or blocking becuase their concentrated loads will overload the rim joist alone. Thus, IRC says at least two sets of connectors, one near each corner, if you chose this method. My interpretation: they are not saying you have to have those tension connectors, they are saying you might need them, and you better be smart enough to know when you do, and do something about it in your deck design.
The house sub-fl. diaphragm must be adequately nailed to the joists, blocking and rim joist; and the rim joist must be adequately nailed to the sill plate or double top pl.; that’s what gives the rim joist the ability to take some lateral load from the deck if needs be. I think your tables will show that through bolts with washers are somewhat stronger than lag bolts (pull through vs. pull out with short screw embedment), in holding the ledger to the bldg., and neither of these fasteners should be cantilevered from the rim joist and solid sheathing through insulation board and/or siding to the ledger for proper support w.r.t. vertical deck loads. And, don’t forget proper ledger flashing. For vertical loads the lag bolts must be regularly spaced and of adequate number and size to make the ledger act as if a continuously supported shelf as it picks up deck joist loading. Lag bolts to widely spaced get overloaded and cause the ledger to act as a beam btwn. the widely spaced fasteners, not particularly desirable.
Joist hangers are primarily designed for vert. loading from the joists, but they do have some ability to resist lateral loads (shear loads parallel to the ledger) and they even have some small ability to resist tension loads down the length of the joist, just not much. The deck can see lateral loads from wind on exposed surfaces, floor structure, guard rails, and privacy walls; earthquakes where the center of mass is some distance from the bldg. and might include DL, snow load, LL as part of that mass; and 4 or 5 - 300 lb. linemen standing out at the railing and swaying back and forth in a drunken group hug, plus all the other people out on the deck dancing to the same music. Now, for the sake of the point that I am trying to make, assume two different decks: one which runs out 10' perpendicular to the bldg. and 12 or 14' along the bldg. and the center of mass is out at 5-6' from the bldg. with the linemen out at 10'; vs. a deck which runs out 18' perpendicular to the bldg. and only 10 or 12' along the bldg. Any of these potential lateral loadings is trying to rip the deck away from the rim joist/fl. system; causing tension at one edge (corner) of the deck and compression into the bldg. at the other deck corner. Given the nature of the beast, the tension loads will be concentrated in the outermost 2 or 4 joists, tending to rip them away from the buidling. I submit that I can most likely make the 10x12 deck work without any special tension hardware, but the 18x12 deck will most likely need special tension hardware and bracing out at its far end. I would probably attach this hardware to the 1st or 2nd interior joist on each edge of the deck since I don’t know which direction the lat. load might be applied. These same connector sets should probably be attached to interior joist or blocking becuase their concentrated loads will overload the rim joist alone. Thus, IRC says at least two sets of connectors, one near each corner, if you chose this method. My interpretation: they are not saying you have to have those tension connectors, they are saying you might need them, and you better be smart enough to know when you do, and do something about it in your deck design.
Yankee
Registered User
Thanks dhengr, you remind me that it is sometimes beneficial to stand back a few feet from the codebook and get a feel for the overall situation.
Francis Vineyard
Registered User
Reference: 2009 IRC fig. 502.2.2.3
R502.2.2 Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable.
R502.9 Where posts and beam or girder construction is used to support floor framing, positive connections shall be provided to ensure against uplift and lateral displacement.
Reference: Simpson Strong-Tie Deck Framing Connection Guide; Hurricane Ties addresses R502.7 & R502.9 Uplift & Lateral displacement
Post to Beam connectors and through bolts with washers addresses R502.9 – Lateral support
Reference: DCA6-09 page C9
While Item 7 of DCA 6 Minimum Requirements states that the document does not address wind or seismic design issues, some interpret R502.2.2 to be applicable in all cases since lateral loads can be developed by other sources including people moving or dancing o a deck. Another interpretation is that the term “as applicable” in R502.2.2 means the provision is only required for code prescribed loads. The only code prescribed lateral loads are wind and seismic.
We will adopt 2009 IRC on March 1st and I just started updating our deck sheet and am of the opinion that the connector shown in figure is required for wind and seismic loads where applicable. The other perspective is to infer “what if’s”.
Do you agree or disagree?
R502.2.2 Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable.
R502.9 Where posts and beam or girder construction is used to support floor framing, positive connections shall be provided to ensure against uplift and lateral displacement.
Reference: Simpson Strong-Tie Deck Framing Connection Guide; Hurricane Ties addresses R502.7 & R502.9 Uplift & Lateral displacement
Post to Beam connectors and through bolts with washers addresses R502.9 – Lateral support
Reference: DCA6-09 page C9
While Item 7 of DCA 6 Minimum Requirements states that the document does not address wind or seismic design issues, some interpret R502.2.2 to be applicable in all cases since lateral loads can be developed by other sources including people moving or dancing o a deck. Another interpretation is that the term “as applicable” in R502.2.2 means the provision is only required for code prescribed loads. The only code prescribed lateral loads are wind and seismic.
We will adopt 2009 IRC on March 1st and I just started updating our deck sheet and am of the opinion that the connector shown in figure is required for wind and seismic loads where applicable. The other perspective is to infer “what if’s”.
Do you agree or disagree?
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dhengr
Bronze Member
Francis:
I agree.... to disagree. You guys and your darn new editions of codes, you’re outpacing me at warp speed. I don’t even get started digesting one, when I’m getting another one rammed down my throat. Tell your legislators not to adopt the next one and explain that they won’t have building falling down around them while doing this, you want to learn to understand the one you have now. And then, each time the question becomes... but there is still some unusual, unlikely, unanticipated condition that isn’t explicitly addressed by the new edition, now what do we do. People loads do cause vertical loads and lateral loads and we better design for all reasonably anticipated lateral loads. What the heck ever happened to a little common sense and engineering judgement and experience? The code just sets the min. magnitude of the loads it lists, it certainly doesn’t say you don’t have to consider other possible or likely loads, and I don’t see any “what if’s” about that. You are sorta asking that a code be written to take this experience factor into account in such a way, that any damn fool (and, I don’t mean you) can do the almost impossible without any thought or knowledge about what he/she is doing, or the consequences thereof. As a structural engineer, I always thought that the only loads I had to design for were those which might make my structure fail, become unserviceable, seriously harm someone or not perform the function for which it was intended and being designed. All the other loads and conditions would take care of themselves. I never thought to scour the code to see if meteorite impacts, or tsunami waves on a high desert plateau, might affect my structure; the old common sense, judgement, experience thing again, or in accordance with well established engineering principles and practice.
To me, ‘where applicable or as applicable’ means if it is reasonably likely to occur, design for it. That’s what your 2nd and 3rd paras. say. While SIMPSON’S guide is a good guide for alerting you to all the potential problem details, remember they are trying to sell their hardware, it may not all be req’d. Reread my 22DEC10 post, I give a few fairly simple examples of what to watch for or when to call for help. Send me copies of those code sections and that SIMPSON guide so I can take a look at them. Maybe we can discuss some other details or items to watch for.
It should be sufficient to say that the deck should be supported in such a fashion as to take all of the anticipated loadings imposed upon it, in the process of performing its intended function. And, IF YOU do not know that means, you have no business building that deck, and you should hire someone who really does know what he/she is doing, if you want a permit. Furthermore, this code section does not protect every damn fool from his/her ill thought out actions.
There are several pretty good deck design guides out there and I think I would just hand out copies of one of them along with the applicable code sections. I’m not sure I would want to try rewriting the history of Structural Engineering, on my own, for public distribution. That’s just sticking your neck out a mile, even if it is tough to sue you guys, for little gain in the public’s ability to grasp the nature of the problem. Do this study for your own edification, to develop your own check list of what to watch for, so when you check a deck plan (I don’t like the words approve or bless in this context), you know when to tell them they need an engineer to do this if they want a permit. You don’t need to give them your check list, but if they miss too many items on it, that might be an indication that they have no idea what they are doing and need some design and building help, and closer inspection.
The question then becomes: should we design for 10 dancing cheerleaders or 5 defensive linemen and that’s further complicated by the fact sometimes there are only three down linemen and at others they are all dancing even the linebackers. Where do you draw the line, the code doesn’t cover this, common sense and judgement does. So, now lets argue about the meaning of reasonably likely.
We can’t design against or codify things to prevent stupidity or to compensate for lack of knowledge. Some of them just exist. And, hopefully natural selection weeds them out, without the courts blaming their existence or actions on you and me.
I agree.... to disagree. You guys and your darn new editions of codes, you’re outpacing me at warp speed. I don’t even get started digesting one, when I’m getting another one rammed down my throat. Tell your legislators not to adopt the next one and explain that they won’t have building falling down around them while doing this, you want to learn to understand the one you have now. And then, each time the question becomes... but there is still some unusual, unlikely, unanticipated condition that isn’t explicitly addressed by the new edition, now what do we do. People loads do cause vertical loads and lateral loads and we better design for all reasonably anticipated lateral loads. What the heck ever happened to a little common sense and engineering judgement and experience? The code just sets the min. magnitude of the loads it lists, it certainly doesn’t say you don’t have to consider other possible or likely loads, and I don’t see any “what if’s” about that. You are sorta asking that a code be written to take this experience factor into account in such a way, that any damn fool (and, I don’t mean you) can do the almost impossible without any thought or knowledge about what he/she is doing, or the consequences thereof. As a structural engineer, I always thought that the only loads I had to design for were those which might make my structure fail, become unserviceable, seriously harm someone or not perform the function for which it was intended and being designed. All the other loads and conditions would take care of themselves. I never thought to scour the code to see if meteorite impacts, or tsunami waves on a high desert plateau, might affect my structure; the old common sense, judgement, experience thing again, or in accordance with well established engineering principles and practice.
To me, ‘where applicable or as applicable’ means if it is reasonably likely to occur, design for it. That’s what your 2nd and 3rd paras. say. While SIMPSON’S guide is a good guide for alerting you to all the potential problem details, remember they are trying to sell their hardware, it may not all be req’d. Reread my 22DEC10 post, I give a few fairly simple examples of what to watch for or when to call for help. Send me copies of those code sections and that SIMPSON guide so I can take a look at them. Maybe we can discuss some other details or items to watch for.
It should be sufficient to say that the deck should be supported in such a fashion as to take all of the anticipated loadings imposed upon it, in the process of performing its intended function. And, IF YOU do not know that means, you have no business building that deck, and you should hire someone who really does know what he/she is doing, if you want a permit. Furthermore, this code section does not protect every damn fool from his/her ill thought out actions.
There are several pretty good deck design guides out there and I think I would just hand out copies of one of them along with the applicable code sections. I’m not sure I would want to try rewriting the history of Structural Engineering, on my own, for public distribution. That’s just sticking your neck out a mile, even if it is tough to sue you guys, for little gain in the public’s ability to grasp the nature of the problem. Do this study for your own edification, to develop your own check list of what to watch for, so when you check a deck plan (I don’t like the words approve or bless in this context), you know when to tell them they need an engineer to do this if they want a permit. You don’t need to give them your check list, but if they miss too many items on it, that might be an indication that they have no idea what they are doing and need some design and building help, and closer inspection.
The question then becomes: should we design for 10 dancing cheerleaders or 5 defensive linemen and that’s further complicated by the fact sometimes there are only three down linemen and at others they are all dancing even the linebackers. Where do you draw the line, the code doesn’t cover this, common sense and judgement does. So, now lets argue about the meaning of reasonably likely.
We can’t design against or codify things to prevent stupidity or to compensate for lack of knowledge. Some of them just exist. And, hopefully natural selection weeds them out, without the courts blaming their existence or actions on you and me.
Francis Vineyard
Registered User
Finally, to address concerns in high-wind zones and ensure that the rimboard is adequately anchored into the floor system (Figure 2), Section R502.2.2.3 requires positive anchorage of the deck joists to the floor framing (this provision is similar to a FEMA construction requirement):
Cheri B. Hainer is a code-enforcement official in Fairfax County, Va.
Article; http://www.deckmagazine.com/article/47.html
Cheri B. Hainer is a code-enforcement official in Fairfax County, Va.
Article; http://www.deckmagazine.com/article/47.html
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There is a slight exception to what brudgers said. Some of the simpson hardware pieces can be calculated using the code provisions for light gage metal and wood fasteners which would allow their use without constituting an alternate method of compliance. This might result in slightly lower values.