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Deck Lateral Load Protection

I am hoping that there will be some eye opening data. Here is what I have read so far that stands out:

Dr. Bender said that while important discoveries were made, they were not comprehensive enough to use as a basis for modifications to the current lateral-load details provided in the IRC. The results were limited by the few conditions tested. More tests are needed, but there is a lack of funding to perform them.
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The above statement was from this link: The 2015 IRC and Decks - Codes And Standards - Professional Deck Builder Magazine
 
Here's another quote from the VT testing, asked no one.

In both tests, splitting of the top edges of the deck joists was the main source of damage, and was caused by the couple from the deck screws that induced stresses perpendicular to the grain. Splitting propagated along the longitudinal axis of the wood. Each deck joist completely split, to the depth of screw penetration, from the load drag strut to the ledger board. Significant yielding and fracture of deck board screws was also observed in this region. Minimal joist splitting and screw yielding was seen in the region from the load drag strut to the outer deck beam. In both tests, no damage was observed in the deck ledger to house rim board connection. A maximum separation of 0.1 inches when hold-downs were used and 0.15 inches when hold-downs were not used was recorded between the deck ledger and diaphragm rim board at the tension chord of the deck. No damage was observed in the simulated house diaphragm.
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The reference to "both tests" means one ledger with hold downs and one without.

I so wish this article was free to all...it is such important information. Please consider subscribing to Wood Design Focus and help support these researchers.

I simply wish to get you all thinking about the information that is sure to get mainstream in due time. Indeed the hold downs made no difference in the testing...the only thing left to cling to is "structural redundancy". We should be willing to challenge that with questions and discussion.

The committee asked for a "study about the band joist connection to the house". They got the lateral load anchor instead. Now we have the study they asked for and the answer is:

"No damage was observed in the simulated house diaphragm". i.e the band joist.
 
So my assumption (yes we all know what it is when one assumes) is that NADRA is hoping that testing will reveal that there is no need for lateral restraint as long as the ledger is properly installed and does not fail by itself or with the band joist. This way they can get rid of that pesky "troublesome" language about the prescriptive method of attachment that unscrupulous, uninformed, pathetic code officials make them install when they don't really have to. My guess is that Simpson will have a new connector to address this issue by then that won't require invasive attachment into the interior of the structure.
 
Glenn said:
Jeff...did you catch who the author was of that article? It might be familiar... It was written before the final research reports I have been sharing here were in my hands.
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Why yes I did, that is why I provide the link and that is how I found the paper. I believe you are the author who is the technical representative of NADRA and represents them at the ICC hearings for code changes. Who better to represent contractors at the ICC hearings than a code official!
 
jar546 said:
Who better to represent contractors at the ICC hearings than a code official!
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Agreed. I understand code very well, and I have been in their shoes as a deck builder. I also listen to them...someone should. Thanks! I also represent my City and my ICC chapter.

Please understand, however, NADRA is not a contractor's association. It is the North American Deck and Railing Association. Our membership is the industry, not just the contractors.
 
jar546 said:
So my assumption (yes we all know what it is when one assumes) is that NADRA is hoping that testing will reveal that there is no need for lateral restraint as long as the ledger is properly installed and does not fail by itself or with the band joist. This way they can get rid of that pesky "troublesome" language about the prescriptive method of attachment that unscrupulous, uninformed, pathetic code officials make them install when they don't really have to. My guess is that Simpson will have a new connector to address this issue by then that won't require invasive attachment into the interior of the structure.
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Now we have new information. Why's that so bad. I've read the testing reports, so I know well what they reveal. I am the one that encouraged NADRA that now is the time to bring the answer to the question asked by the committee in 2007. Does the ledger to band joist connection resist lateral loads? Just pretend for a minute they do...why is that so horrible?
 
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I have been following this lateral load provision since if first came to the 09 IRC. This article from late 2009 discusses how it got in the IRC and it's implications.

New Code for Resisting Lateral Loads - Codes And Standards, Structure, Engineering, Building Science - Professional Deck Builder Magazine

I mentioned before, it was the committee response for "study of the band joist connection" that drove this provision. When the public commenter brought the lateral load detail in response, they brought the following argument:

Deck failures do occur where the deck is attached to the rim joist for lateral loads, but the rim is not adequately anchored into the floor system. Positive anchorage of the deck joists to the floor framing addresses this potential failure. The figure is based on a similar figure from FEMA 232.”
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The argument from the proponent to get this in the IRC was about concern for the rim joist connection to the floor system. This is what I describe in my video.

Now we have testing that says neither the ledger connection to band joist or band joist connection to house failed at loads 4 times that greater than occupants can generate.

This is what I am trying to get your attention to. If there are other lateral load concerns (like nails in hangers), let's address them. But let's not have any more research, products, or alternatives based on code provisions included in the IRC that have been subsequently found inaccurate. If I have a deck with a ledger that is 30 ft. long, I've got at least 23 joists, 1500 lb hold downs on only two joists doesn't seem like an appropriate design. Let's talk about what is. Perhaps screws in hangers...

In the meantime, we should remove what we know is not necessary and provide more freedom to research and innovation to not be based on 1500 lbs in two locations. And let's relieve the decking industry a little. It's not all about the cost of the hold downs, it's the cost of their installation. In regions with finished basements or second floor decks it adds an interior remodel aspect of the job. With engineered floor joists, (six feet in of blocking) that can be a big deal.

--Of the four lateral load articles I reference, all of them were guided in some way by the current code language of two 1500 lbs connections. Future research should not be bound by that any longer.

--ICC ES has already worked on acceptance criteria for alternative methods for getting two 1500 lb concentrated load connections. Why? Why do we want this in the code until 2018 to continue to mislead innovation to creating a product equivalent to an IRC load of 1500 lbs that turns out is not really the target. Why? We need a clean slate.

I think I've provided enough information here to show that this subject does need further discussion and development. We do not have the answer yet, but it is not 1500 lbs in two locations according to the most recently released information.
 
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NOTE:

I have mis-credited some of the testing that occurred. All the testing occurred at Washington State University, not Virginia Tech. Dr. Woeste was not the lead researcher, it was Dr. Bender.

My apologies for any misleading in credit or location as to how the testing was handled.
 
When this situation is resolved, the next thread started needs to ask the vinyl railing manufacturers how an aluminum plate and 4 screws for the base of a railing vertical support constitutes meeting a 200# limit and how were we suppose to inspect this to being with. Anyway, no more hijacking, we can start another thread for that.
 
jar546 said:
When this situation is resolved, the next thread started needs to ask the vinyl railing manufacturers how an aluminum plate and 4 screws for the base of a railing vertical support constitutes meeting a 200# limit and how were we suppose to inspect this to being with. Anyway, no more hijacking, we can start another thread for that.
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Manufactured guard assemblies often omit testing of the connection point to the floor they serve, under the disclaimer of "we don't know how they built it". Other times when the connection is tested, in the fine print of the testing, you will find that plate was connected to concrete. There is a lot of discussion to have regarding guards.
 
We use the"Prescriptive Residential Wood Deck Construction Guide based on the 2009 IRC" put out by the American Forest & Paper Asoc. It requires lateral load connection.

But what about porches (covered deck). Does everyone require lateral load connections for porches? Usualy there is no rot problem then. Also you don't get snow and rain except some on the edges. Should I go by the IRC or the deck guide?
 
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