Deck Ledger and Lateral Loads

[Glenn]

Are you curious about the new provisions in the 2009 IRC for lateral loads on decks? Are you curious about the complicated ledger fastening provisions in the 2012?

These videos will answer many of your questions...and leave you with many more. They are worth the time to watch.

Are the 2012 Ledger connection requirements even feasible? You decide.

IRC Ledger Bolting Pattern - YouTube

What's the deal with the strange "shall be permitted" lateral tension device for decks? Here's a little background and insight.

Lateral Load video - YouTube

An Inside Look | Building Code College

 

[DRP]

I would certainly be interested in taking an entire codebook full of instructional classes but I'm afraid you are blowing this carpenter's tuition money on the first segment. You'll do more training of the footsoldiers if you get the price in line. That depends on what I always wonder with the cow, what is the goal here?

One way to ease the financial pain in that, a portion of our permit fees goes to an education fund, have those funds help subsidize a free or low cost online code college for anyone interested. Not only should the law be carved in stone and placed in the town square. For most of us languagewise it's gotta be this side of the KJV, I don't do Greek. IF the law was written by people who no longer speak their mother tongue, then the translation should also be carved in stone and placed in the town square for all to see and know. There is the part I hope you will help with in your new rollout, think about the potential audience and alternative funding.

 

[Rio]

After looking at the video I kept thinking 'How could something so basic be made so complicated?' When California adopts the new code it looks like we'll be doing stand alone decks only.

 

[Glenn]

Thank you for your comments, DRP.

I realize that there is plenty of free or cheaper education available online, but it's likely soft marketing...and risk of bias. This education is straight, true and plumb. It's about helping both sides of the building department counter to understand the code and apply it appropriately. I appreciate your comments about the cost, and will continue to work on a market viable product that can win your enrollment.

I hope you enjoyed the free video I posted above. The codes are changing quite drastically for decks.

My sentiments at DECKCODES.COM | SaferDecks reveal what prompted me to write my ICC deck code book, and is the same motivation that drives BuildingCodeCollege. I think you will find it pleasantly parallels your statements above about availability of codes to the builders.

 

[Frank Woeste]

ICC Building Code Action Committee considers very large proposal

http://www.nadra.org/contractor-code-guide/ICC_Committee_Proposal_2015.pdf

 

[Glenn]

Do you require all decks to have lateral load anchors to be installed? Some decks? None? I'd like to hear how you guys are handling this new world of code for decks.

My jurisdiction has been on the 2009 for years, and we have yet to demand these on any decks. We also haven't demanded that any anchors be removed...since they "shall be permitted" ha, ha, ha!

Our citizens are not prepared, nor would they be very happy, if we started having ceilings below floors torn out for every deck. We have a lot of finished basements and two story homes.

The proposal that Dr. Woeste provided intends to require every single deck, low, small, tall, big to have two anchors installed...or else have an engineered design. I'm not sure that's a good idea.

Should all decks be designed by a licensed engineer?

When you look at the provisions for ledger bolting under 2012 I think the fact of the matter is:

1) The backside of all band joists supporting decks will need to be made visible.

2) It's going to be so hard to prescriptively attach the ledger that an engineered design will be required.

People just won't permit their decks anymore if it goes this way. When decks become criminal, only criminals will have decks.

 

[DRP]

Reading the NADRA proposal a couple of questions popped up. It specified 2x6 decking, does 5/4 x 6 fail to make span? There has been much made of ledger attachment and the lateral connection device OR we may build the deck freestanding and brace per the document. Does this bracing provide the same lateral stability to the deck structure as a ledgered deck? When we bury free standing deck posts against a building is there a point of fill that precludes the need to brace the post, eg on a recent house we buried the posts along the foundation wall 7' from gravel footing to grade, not wanting to drill and attach to Superior Walls, up ~18" from grade to the girder bottom, has the fill sufficiently braced the post and where is that line.

How many properly bolted or lagged ledgers have had a lateral failure... is this common enough to need adressing?

 

[Glenn]

EEEK!! That is NOT a NADRA proposal!

I just got wind of it recently. It is a from the ICC Building Code Action Committee, though there is a lot of other history behind it from Virginia, I believe. All the questions DRP proposes and more are exactly what we are thinking. The BCAB has asked for input on the document in both support and opposition prior to submission and prior to the hearings. This is why NADRA has posted it to our blog so our members can see it and share it. I believe many people will think as we do on the subject, much like described above by DRP.

There is some very good and helpful information within it that we plan to support...and there is a lot of other stuff we will not.

Here is the link to the document on ICC, titled "IRC Section 507 deck_strawman_10-22"

Bottom of the page:

Building Code Action Committee (BCAC)

 

[Dennis]

People just won't permit their decks anymore if it goes this way. When decks become criminal, only criminals will have decks.

This is happening everywhere. Around here if you build a small deck outside the house or replace the outdoor stairs then you need a permanent- Now cabon/smoke detectors are required inside the home.

Can you imagine going to someones house to add a receptacle in an existing room say coming from an outlet just on the other side of the wall. Normally we could do this job within an hour and it would cost about $125. Now add a permit- minimum here $60.00, now add the afci- another $50.00. Sp now the job is twice the cost. Most EC will go in an add an outlet- no permit and no afci-- can't say I blame them.

 

[jar546]

Deck Ledger and Lateral Loads

After witnessing the aftermath of a few deck collapses, I see and understand the need for the lateral tie backs. I don't care if they have a finished basement with drywall. Who am I to waive the requirement because I feel sorry they have to do some drywall work.

Sent from my iPhone using Tapatalk

 

[DRP]

Of the deck collapses you all have seen how many involved a properly lagged or bolted ledger?

 

[jar546]

Both collapses were due to lack of proper flashing which rotted out the rim board. No amount of lags can help that. The tiebacks from joist to inside joist would have kept it from dropping all the way to the ground. The ledger is no longer a factor.

 

[Mac]

New York includes this paragraph, since 2007...

R502.2.1 Decks. 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. Such attachment shall not be accomplished by the use of toenails or nails subject to withdrawal. Where positive connection to the primary building structure cannot be verified during inspection, decks shall be self-supporting. For decks with cantilevered framing members, connections to exterior walls or other framing members, shall be designed and constructed to resist uplift resulting from the full live load specified in Table R301.5 acting on the cantilevered portion of the deck.

 

[DRP]

Both collapses were due to lack of proper flashing which rotted out the rim board. No amount of lags can help that. The tiebacks from joist to inside joist would have kept it from dropping all the way to the ground. The ledger is no longer a factor.

A valid point, the only deck failure I have been a part of was the same, no flashing, the rim came out with the ledger.

 

[Glenn]

The tiebacks from joist to inside joist would have kept it from dropping all the way to the ground. The ledger is no longer a factor.

The inclusion of the tiebacks in the IRC was a result of concern about how well the rim joist is connected to the rest of the framing. However, I have heard a few people refer to it like you have...as a sort of safety device in case of failure due to poor construction. This brings a few thoughts to mind.

1) If the tiebacks are intended to "catch" the deck in case the ledger rots out from poor flashing...half the effort used to install these anchors could be used to flash the ledger better instead. Then you eliminate this argument. My point is the decks that are failing got little to no attention when built...now we are on the opposite of the spectrum. Well-flashed ledgers so the band won't rot, and hold back anchors for when it does? That hurts my brain.

2) The 1500 lb resistance is tested laterally. As a horizontal load. If the band/ledger were to fail completely from rot and the lateral anchors were used to "keep it from dropping to the ground" there is going to be a tremendous moment (rotation, torque) on the all-thread and the anchors from the downward force of the deck that would otherwise fall. This is not how these anchors or assembly of anchors were tested or intended to perform.

3) Even if the anchors/all thread assembly was designed or could otherwise handle the rotation force placed on them from the falling deck, 3,000 lbs (anchors in two locations) isn't going to get you far when it comes to vertical loads. The dead load of 10 psf alone would only get you a 300 sf deck. All the deck failures I have seen were during periods of live loading. Add that weight and you hit 3,000 really quick.

My point:

The notorious deck failures during prom photos and parties from rotten band joists and nailed ledgers would not have been held up under those conditions by a couple lateral anchors suddenly put under torque from downward loads. That is just plain not what they are meant to do.

Half the effort it takes to install these anchor per spec and to analyze the ledger and band joist for bolt placement (2012 IRC) could be used for the following and you'd have decks perform just fine:

1) Stop connecting to cantilevered floors (unsupported band joists)

2) Take the time to well flash the ledger, including installation of self-adhering polymer-modified bitumen (peel n' stick) behind the ledger.

3) Stop connecting to or through anchored brick veneer.

4) Put some lag screws

5) Brace against lateral deformation (racking) that ultimately loosens all the connections

6) End our society's attitude that decks are just so easy to build.

Oh man...I'm off and ranting now... sorry...

 

[GBrackins]

I thought the 1500 lbs lateral load was in the direction away from the house. if the deck were to drop then the threaded rod (lateral connection) would be in shear wouldn't it?

 

[Keystone]

Tension devices, the code does not offer options in lieu of placing the tension devices. What about inside or outside corner walls, other options?

Free standing decks, great in thought but then we run across the pier placement/depth in contrast to the existing foundation and a cantilever can only span so far.

I understand we want a page limited code but when a specific device is added to cure a problem, the device becomes the only source of compliance in the eyes of most because that is what is prescriptive, presciptive needs more options than a manufacturer or the use of a design professional.

 

[DRP]

I understand your point if there is a complete failure the connectors probably won't do more than buy a little time... that might be a better thing than a totally sudden failure. Rated load and ultimate load on the 1500 lb connector are not the same thing, it'll at least give a break in the drop. I will land a whole lot better if you can buy me even a second or two of warning. But, the connector would probably prevent the situation entirely for some time. If the other connections are kept snug even in wood with decay there is a good chance there will not be a sudden failure. If connectors cannot withdraw they will be doing work, things begin to sag and distort but not pull away and fail and we have a nice slow failure, I can go for that. Of course a net of some type of strapping would probably fill the bill just as well, it does feel like a slippery slope. If we set eye hooks high on the wall a person could clip in when they are on the deck. Seems like a reasonable precaution but don't they all.

 

[ICE]

Neglect plays an important role.

 

[Glenn]

Thanks for all your comments and feedback on this topic. I am flying out to Virginia this evening to meet with members of the ICC BCAC and other key players in deck code to discuss the proposal Dr. Woeste posted here. Decks do need better attention in the IRC, but it must be done carefully and with intention.

NADRA's Vision Statement:

"Safe decks with well-thought-out engineering and a common sense, practical approach to code requirements."

Please support this vision in anyway you can.

 

[DRP]

Glenn, If you're meeting in Blacksburg and have time get a tour through Brooks Labs.