Thread: cantalevered deck

Originally Posted by Garry Sorrells

Doing my part to get to 100 posts....

Lets move this to the interior of a home.
Would this be acceptable for splicing a floor joist?

That all depends on whether it would be considered an interior balcony joist splice or an interior deck joist splice. We need to resolve that issue first, gang.

Enough of this procrastination.

Without proper ground support it's an accident waiting to happen.
However, it that balcony, if it is one, would make a large diving board until the Sumo Dive team arrived.

Originally Posted by BridgeMan

That all depends on whether it would be considered an interior balcony joist splice or an interior deck joist splice. We need to resolve that issue first, gang.

Enough of this procrastination.

Balcodeck joist splice?

Chuck said in post #27 that it's a deck, with two support posts.

Kristi,
The point of my description to you was to look at the forces acting on the lumber and connection points. Guess I failed. Sorry. Every jurisdiction has its own codes. As a test take the picture to your local office and get their official opinion on the method of connection. Would love to hear the outcome. Also, most permit offices have a handout for deck construction requirements see if your permit office has one. Might ask if adding a second set of bolts at top might meet their standards.

I will give you another task.
Lets move this to the interior of a home.
Would this be acceptable for splicing a floor joist?

You didn't fail, Garry, but I've been looking at the attachment and the forces on it the whole time, and I respectfully disagree with your analogy implying that having two bolts through the wood weakens it as much as a notch would.

I'm trying to stay away from blanket statements saying it's acceptible or not because we don't know all the info. Likewise it's impossible to say whether it would be an acceptible way of splicing an indoor floor joist without knowing any of the particulars. Please also notice I added that the joint could be reinforced if necessary.

I don't know if it's code, that's not what I'm addressing.

All I'm really saying is that from a structural standpoint it may not be necessary to cut the stubs flush (or recessed), somehow seal them from moisture penetration, put a ledger board up, cut the 2X6s to the right length (hopefully they reach that far) and install joist hangers. There could be easier solutions.

None of us can be certain of anything, that would take bringing in a SE.

Kristi,
"...You didn't fail, Garry, but I've been looking at the attachment and the forces on it the whole time, and I respectfully disagree with your analogy implying that having two bolts through the wood weakens it as much as a notch would. ..."

Not the point, it is that the loads are being concentrated on the bolts as if the wood above the bolts was notched and the deck joist was sitting on a notch ending at the bolt location.

Originally Posted by Kristi Silber

Chuck said in post #27 that it's a deck, with two support posts.



You didn't fail, Garry, but I've been looking at the attachment and the forces on it the whole time, and I respectfully disagree with your analogy implying that having two bolts through the wood weakens it as much as a notch would.

I'm trying to stay away from blanket statements saying it's acceptible or not because we don't know all the info. Likewise it's impossible to say whether it would be an acceptible way of splicing an indoor floor joist without knowing any of the particulars. Please also notice I added that the joint could be reinforced if necessary.

I don't know if it's code, that's not what I'm addressing.

All I'm really saying is that from a structural standpoint it may not be necessary to cut the stubs flush (or recessed), somehow seal them from moisture penetration, put a ledger board up, cut the 2X6s to the right length (hopefully they reach that far) and install joist hangers. There could be easier solutions.

None of us can be certain of anything, that would take bringing in a SE.

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That's the Only Thing We can be Certain of.
* HI's should not write the remedy nor do the correction.
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Hmmm, Garry, I think I do understand you. My point is that notching is not like anything going on here. It's not a good analogy. Sorry, but I just can't see it.

I wonder if the decking is screwed or nailed.

Now that's got me thinking--I wonder if the deck planks are stained or painted?

Originally Posted by BridgeMan

Any wagers as to how long it takes to reach 100 posts on this dying horse
Come on already, it's dead.

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Originally Posted by BridgeMan

Now that's got me thinking--I wonder if the deck planks are stained or painted?

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Now That's Just Stacking "The Deck!"
Everybody knows Painted Joists are Stronger just think about all those Microns of Paint Helping to supporting a Dozen People, Barbeque Grill, DJ Equipment, Ice Chests, Lawn Furniture, Table, Chairs, Baby Carriages Assorted Food and Beverages all Swaying to the Music on Two Big Box Carriage Bolts.
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Originally Posted by Garry Sorrells

So what would you call a cantilevered balcony with no vertical support that has stairs attached to it? Balconized Deck? Balcodeck?

If the balcony is holding up the top of the stair, it is still a balcony.

If the stair is a structure which is holding up that end of the balcony, then it is a deck and not a balcony.

I have seen one ... one ... and the stairs were attached to the balcony and the balcony was holding up that end of the stair. It was a reinforced concrete stair which was riser-tread-riser-tread-etc. all the way to the top. The architect had not even designed a guard rail or handrail for the stairs. The owner eventually agreed that it was enough of a hazard for tipsy friends the he finally over rulled the architect and had guard rails and handrails installed. I've tried to find my photo of it, but I have not been successful yet.

Originally Posted by Jerry Peck

If the balcony is holding up the top of the stair, it is still a balcony.

If the stair is a structure which is holding up that end of the balcony, then it is a deck and not a balcony.

I have seen one ... one ... and the stairs were attached to the balcony and the balcony was holding up that end of the stair. It was a reinforced concrete stair which was riser-tread-riser-tread-etc. all the way to the top. The architect had not even designed a guard rail or handrail for the stairs. The owner eventually agreed that it was enough of a hazard for tipsy friends the he finally over rulled the architect and had guard rails and handrails installed. I've tried to find my photo of it, but I have not been successful yet.

.......

I still can't find the photo, so I drew this up to offer a visual as to what it looked like - in a word: weird, then scary.

Now there is a design marvel. A floating deck. I like it. Is that you Jerry on the stairs? Looks like you may have lost a little weight. Would be great for those scenic overlooks along highways. Does it come in choice of colors?
What is it called? A Stairodeck?

Just for you BridgeMan. A thread that just keeps on giving.............

I forgot what I was going to post now......
Something about a cantilevered pool on a porch-deck with leger-hangy-things....
Oh yea, I was going to state that I used to double every third joist (full length of course) just for poop & giggles. I'm going to bed, tired

Originally Posted by Ken Amelin

I wouldn't use that method of attachment if the deck is still cantilevered, but in my opinion this method of fastening the ends of the new joist to the structure would be acceptable provdied the wood tail pieces that rest within the block foundation are solid . I would also expect to see columns supporting the other end of the joists.

Wow, a lot of electrons were used up on this one! I think Ken got it right...and the issue of balcony vs deck is irrelevant to the question. The 2006 IBC live loading for balconies was 100 or 60 psf, but under the 2009 IBC you design both for the live load of the occupancy the deck/balcony serves.

From a structural standpoint, if the ends of the new joists are supported on a post and beam structural system (not cantilevered) the situation is acceptable.

Originally Posted by Thom Huggett

Wow, a lot of electrons were used up on this one! I think Ken got it right...and the issue of balcony vs deck is irrelevant to the question. The 2006 IBC live loading for balconies was 100 or 60 psf, but under the 2009 IBC you design both for the live load of the occupancy the deck/balcony serves.

From a structural standpoint, if the ends of the new joists are supported on a post and beam structural system (not cantilevered) the situation is acceptable.

Oh, good! A SE came and added his bit to the discussion. But I don't get it - if the situation is dependent on there being support for the new joists, making the structure not cantilevered, that means that whether it is a deck or balcony (by the IRC definitions) does make a difference. No? (Just for clarification.)

And out of curiosity...I was thinking if the decking near the wall is screwed to both new and old joists, that could help support some of the weight on the new ones, while nails might not be so effective because they're more likely to come out. Does that make sense, or am I imagining things?

Originally Posted by Thom Huggett

Wow, a lot of electrons were used up on this one! I think Ken got it right...and the issue of balcony vs deck is irrelevant to the question. The 2006 IBC live loading for balconies was 100 or 60 psf, but under the 2009 IBC you design both for the live load of the occupancy the deck/balcony serves.

From a structural standpoint, if the ends of the new joists are supported on a post and beam structural system (not cantilevered) the situation is acceptable.

Originally Posted by Kristi Silber

Oh, good! A SE came and added his bit to the discussion. But I don't get it - if the situation is dependent on there being support for the new joists, making the structure not cantilevered, that means that whether it is a deck or balcony (by the IRC definitions) does make a difference. No? (Just for clarification.)

And out of curiosity...I was thinking if the decking near the wall is screwed to both new and old joists, that could help support some of the weight on the new ones, while nails might not be so effective because they're more likely to come out. Does that make sense, or am I imagining things?

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And just what is an SE?
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Serious Engineer.

Definition of an Engineer:
What is the definition of an engineer? Answer: Someone who solves a problem you didn't know you had, in a way you don't understand.

Originally Posted by Jerry McCarthy

Serious Engineer.

Definition of an Engineer:
What is the definition of an engineer? Answer: Someone who solves a problem you didn't know you had, in a way you don't understand.

You forgot to add: With an expensive way to fix it. If your an engineer, we are JUST kidding.

Originally Posted by Door Guy

. . If your an engineer, we are JUST kidding.

Or putting it another way (as most of us learned in 3rd or 4th grade)--If you're an engineer, we are JUST kidding.

By the way, engineers don't set or determine prices for work or materials being performed according to engineering standards, designed to keep people safe and alive.

Michael Kober, P.E.

Originally Posted by BridgeMan

Or putting it another way (as most of us learned in 3rd or 4th grade)--If you're an engineer, we are JUST kidding.

By the way, engineers don't set or determine prices for work or materials being performed according to engineering standards, designed to keep people safe and alive.

Michael Kober, P.E.

Michael, no intension to insult you. Please accept my apology. I know you don't set the costs for design, repairs or materials. Good catch on the your and you're I deserved it...

Originally Posted by Jerry McCarthy

Serious Engineer.

Definition of an Engineer:
What is the definition of an engineer? Answer: Someone who solves a problem you didn't know you had, in a way you don't understand.

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Let's give the man an opportunity to respond.( not a PE.)
*SE , CBO ?
Self Employed, Certified Building O something ?
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Originally Posted by BridgeMan

Or putting it another way (as most of us learned in 3rd or 4th grade)--If you're an engineer, we are JUST kidding.

By the way, engineers don't set or determine prices for work or materials being performed according to engineering standards, designed to keep people safe and alive.

Michael Kober, P.E.

You're picking on someone's grammar, and following it with a sentence like that?! How can you perform materials according to anything?

Grammar is obviously not a huge concern around here, so singling anyone out is silly. Play nice! Everyone! Jerry, was that meant to be a joke? I mean, it's a good thing someone can identify problems you guys miss, and understands how to fix them.

Originally Posted by Kristi Silber

You're picking on someone's grammar, and following it with a sentence like that?! How can you perform materials according to anything?

Grammar is obviously not a huge concern around here, so singling anyone out is silly. Play nice! Everyone! Jerry, was that meant to be a joke? I mean, it's a good thing someone can identify problems you guys miss, and understands how to fix them.

The Bridge man is a PE. and is Qualified to write a remedy.( not Silly)
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We don't know who this man that blessed the bolt on is.

Passive–aggressive behavior - Wikipedia, the free encyclopedia

Aggression is Aggression overt or other wise.
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Originally Posted by Billy Stephens

SE , CBO ?

SE would be Structural Engineer, which is a field of Professional Engineer (PE).

A PE can have their engineering in many things, mechanical, electrical, chemical, civil, etc., the SE just clarifies that his engineering is in structural.

CBO is Certified Building Official.

Originally Posted by Jerry Peck

SE would be Structural Engineer, which is a field of Professional Engineer (PE).

A PE can have their engineering in many things, mechanical, electrical, chemical, civil, etc., the SE just clarifies that his engineering is in structural.

CBO is Certified Building Official.

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I'm sure the Gentleman can answer on his own.

Systems Engineer as in Mechanical Code Enforcement came to mind as well.
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Originally Posted by Billy Stephens

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I'm sure the Gentleman can answer on his own.
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I'm sure he can, but, as YOU and the rest of us do, we answer when we know the answer.

The Gentleman STILL can answer, I took off the handcuffs and the gag (so he could not type or use a speech recognition program to answer you) so he is now on his own.

Mr. The Gentleman, be forewarned of this Billy type guy here.

Originally Posted by Jerry Peck

I'm sure he can, but, as YOU and the rest of us do, we answer when we know the answer.

The Gentleman STILL can answer, I took off the handcuffs and the gag (so he could not type or use a speech recognition program to answer you) so he is now on his own.

Mr. The Gentleman, be forewarned of this Billy type guy here.

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As I Noticed The Gentleman was on Line and Choose Not to Respond ( at this time ) He may be rethinking His Structural Comment.
* some of those Code Enforcements Guys can be like that.
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Originally Posted by Jerry Peck

Mr. The Gentleman, be forewarned of this Billy type guy here.

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For clarification, that would be the Billy type guy who likes to use lots of dots.
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I wonder why--was he "dot-deprived" as a child?
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Thom,
You stated "...From a structural standpoint, if the ends of the new joists are supported on a post and beam structural system (not cantilevered) the situation is acceptable...."

Just to clarify my understanding.

Are you saying as a SE (per the picture) that the use of the two bolts is an adequate support and connection for the deck at the house?

Originally Posted by BridgeMan

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For clarification, that would be the Billy type guy who likes to use lots of dots.
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I wonder why--was he "dot-deprived" as a child?
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Man.
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I Gots to Get Me Some of Dem Dots...
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Chuck confirmed his photo is of a deck so why all the dissertations?
Decks are supported from the ground, balconies are not. Stairs play no part unless they are part of the deck support system. The IRC and CBC are clear on the difference between a deck and a balcony.

BTW, note that the bolting connections of the sistered joist where not staggered. This could easily lead to a split out and failure. Still need an SE to bless it.

A closer view.

Jerry M.,
I had tried to describe that concern to Kristi in post #54. Hope your description as ":..a split out and failure..." makes it clearer.

Maybe Thon will clear it up as a SE. Even though it may not be acceptable in MN but may be in CA.

The back and forth on what type of deck really was not the basic issue with the OP pict., think it was more of some fun and banter.

Have to ask, what if the platform is hung from above (cables), what is it?

And the thread continues..................

Garry, what makes you think I don't understand what you're saying? I understand it fine, I just don't agree with it. Thom the SE already stated his position, he said it was acceptible. Whether it's a deck or a balcony IS important because it determines the stresses on the bolts and joists - not only how much, but what direction.

If suspended with cables from the building from which it's accessible, it's a balcony.

[quote=Jerry McCarthy;193405]Chuck confirmed his photo is of a deck so why all the dissertations?
Decks are supported from the ground, balconies are not. Stairs play no part unless they are part of the deck support system. The IRC and CBC are clear on the difference between a deck and a balcony.

BTW, note that the bolting connections of the sistered joist where not staggered. This could easily lead to a split out and failure. "Easily"? Perhaps on a balcony, but far less likely on a deck; the 2X8 is also short and well supported at the wall and the bolts are relatively far apart. Still need an SE to bless it. On-site, you mean?[/quote]

It seems strange to me that people seem so convinced this wouldn't work.

Originally Posted by BridgeMan

Sounds good on paper, but should the deck collapse after being filled with many tons of people the owners have invited over for the grand house warming-party, you know the question that will be raised--"Why didn't our home inspector tell us to have an engineer take a look at it, when he knew (or should have known) it doesn't meet Code?"

Competent general contractors are not allowed to practice engineering, and asking them to do so is risky, if not illegal.

[quote=Kristi Silber;193412]Garry, what makes you think I don't understand what you're saying? I understand it fine, I just don't agree with it. Thom the SE already stated his position, he said it was acceptible. Whether it's a deck or a balcony IS important because it determines the stresses on the bolts and joists - not only how much, but what direction.

If suspended with cables from the building from which it's accessible, it's a balcony.

Originally Posted by Jerry McCarthy

Chuck confirmed his photo is of a deck so why all the dissertations?
Decks are supported from the ground, balconies are not. Stairs play no part unless they are part of the deck support system. The IRC and CBC are clear on the difference between a deck and a balcony.

BTW, note that the bolting connections of the sistered joist where not staggered. This could easily lead to a split out and failure. "Easily"? Perhaps on a balcony, but far less likely on a deck; the 2X8 is also short and well supported at the wall and the bolts are relatively far apart. Still need an SE to bless it. On-site, you mean?[/quote]

It seems strange to me that people seem so convinced this wouldn't work.

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The Bridge man is a PE and has not signed off on the shown bolt up.
* have you read his post?
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A thread that just keeps on giving.
Kristi, Congratulations on being 100 post.
Billy, Congratulations for being first on page 2.

Reading Billy's re-quoting of BridgeMan's comment, "Competent general contractors are not allowed to practice engineering, and asking them to do so is risky, if not illegal." raised an interesting thought about who is qualified to offer an assessment of structural issues. In Oregon (BridgeMan location) it may be that only a SE can address a constriction design issue. While other states allow a Contractor (typically Licenced) to make a determination of structural issues. Usually stated as a qualified professional (or something similar). Contractors routinely make structural design and engineering decisions. Those decisions are based on the accepted or required building practices which have been at some point signed off by some engineering authority. Thinking back over the years I can not remember but one occasion that a SE called in actually sat down and did the actual calculations for their offered proposed solution to a problem. Most of the time the SE as the does the Contractor rely on the prescribed standards of their jurisdiction to evaluate a situation. Reapplying someone elses work every day. A contractor does not mathematically determine the size of material for a span, they use a prescribed table for that determination. Like a SE the Contractor takes the responsibility for their evaluation and reasoning. Contractors don't practice structural engineering, they apply the engineering standards as locally required.

Not casting any shadow over the SE profession nor wanting to start an argument. Just posting an observation and thought.

Originally Posted by Thom Huggett

Wow, a lot of electrons were used up on this one! I think Ken got it right...and the issue of balcony vs deck is irrelevant to the question. The 2006 IBC live loading for balconies was 100 or 60 psf, but under the 2009 IBC you design both for the live load of the occupancy the deck/balcony serves.

From a structural standpoint, if the ends of the new joists are supported on a post and beam structural system (not cantilevered) the situation is acceptable.

Thom,
Still would be interested in your opinion on the attachment and support of the deck to the house structure, in general or Oregon specific. As a SE would you accept the two bolt pattern as seen in the picture as being adequate engineering design?

Kristi,
Billy and I seem to read Thom's response to as directed as the deck being supported by post and beam and if so making it not cantilevered therefore acceptable in the aspect of cantilevering. It may be parsing of the the sentence, but still question the bolting method.

Why is it hard to accept? 40 years of building experience. I may be wrong and would not be the first time. If I am wrong I want to understand why.

"It seems strange to me that people seem so convinced this wouldn't work."

Kristi
Strange? The original cantilevered joist look a bit aged & deteriorated in the photo put up; however, none of us other than the original poster have been on site so all of our opinions are based on a photo that is basically incomplete.

I opined based on 61 years of construction experience and from a partial photograph and from what I see I would no sooner go on that deck than bungee jump off a bridge. "May be all right" is not good enough for these old eyes and until a state licensed SE makes a thorough site inspection of that repaired deck we will probably never know the extent of structural stability of that "repaired" deck?
Ask yourself this; what would you say to your client if they asked “is the deck safe?”

Whew! Nice to not have to wait for the whole page to download.

Billy and I seem to read Thom's response to as directed as the deck being supported by post and beam and if so making it not cantilevered therefore acceptable in the aspect of cantilevering. It may be parsing of the the sentence, but still question the bolting method.

I'm afraid I don't understand, "if so making it not cantilevered therefore acceptable in the aspect of cantilevering." I was under the impression that Thom was aware of the attachment method, but I don't know. At any rate, I don't take his assessment as the final word, either, since he knows no more than any of us about the structure as a whole.

It's not the doubt that it would work that I find strange, it's the conviction that it wouldn't - the definitive answers people give, based on so little information. People were judging it before even knowing if the whole structure was cantilevered or supported elsewhere, and to my mind that is a pretty critical issue.

I don't know whether I would tell a client if it's safe or not because I don't know anything about the rest of the deck. What if this is only four feet wide, from wall to railing? That makes a big difference in terms of both live and dead loads, versus a deck that is 10' wide.

As I said multiple times before, my main point is that using the stubs to attach new joists doesn't seem to me in itself problematic. If the attachment is not adequate it can be reinforced, rather than taking the whole thing apart and putting up a ledger board.

Wow, what a lot of time people have on their hands! I had no idea what a stir I created while taking a long weekend. I don't have time to read all the posts, but here is my reply....

First of all, I am a Registered Professional Civil and Structural Engineer in California, but I try not to take myself too seriously (Serious Engineer? ). I am also an ICC (International Code Council) Certified Building Official and Certified Plans Examiner. I have served as the Building Official for a California city and county, but am now Principal Structural Engineer in Contra Costa County, which is located in the east San Francisco bay area. But enough about me....

The original question was whether joists could be attached to the end of the existing stubbed joists, with the assumption that the existing joists are sound. The simple answer is yes, assuming that the existing joists are not asked to support too much load. There are 2 different ways that the load could be applied; as a continuation of the cantilever (balcony?), or as the reaction from simple span joists (the other end supported by posts and beam). There are many factors to consider, but probably the former would not work. However the latter, taking into account the span length, etc., could be made to work. You might have to add an extra bolt, but in theory it should work. An added ledger would serve no purpose, although blocking between the added joists would be advisable.

As I stated before, the only difference between a balcony and a deck, from a structural standpoint, would be the live load that must be applied to the structure. Under the 2006 IBC there is a difference, however under the 2009 IBC the live load is equal to that of the occupancy that the deck/balcony serves, which would be the same in either case.

From glancing through the posts it may be that balcony/deck concern is that the joists for a balcony are usually cantilevered while for a deck they are usually simply supported by posts and beams. My response to this concern is in my 3rd paragraph above.

Here is a better definition of engineering:

The practice of:

1. Using materials whose properties that we don't really understand,
2. In conditions that we don't really know how to analyze,
3. To withstand forces that we can't predict,
4. And to do all in such a way that the general public has no idea as to the extent of our ignorance.

Thorn,
Thanks for your reply. Yes, seems a lot about what is not seen in the picture, some of it is just having a little fun with each other.

Part of you respoce, "... You might have to add an extra bolt, but in theory it should work...." ...."...blocking between the added joists would be advisable..." goes along with Jerry M.and my thought that additional bolts would be necessary. Most all seem to agree that what is depicted int he picture needs more than what is there art present. Though I would have approached the attachment differently.

Now Garry, it wasn't just you and Jerry M who said additional attachment might be necessary - I said the same thing. In fact, all along I've been saying the same thing Thom said, and Jerry M told me I "couldn't be more wrong."

Thanks, Thom, for coming back into the fray! What a crazy thread.

Thanks for the kind words.

I have been following this website for a while, and I think, for some of these situations, if we were all sitting in a room together discussing them there wouldn't be quite so many misunderstandings. It's sometimes hard to express yourself in writing, even when using the little smile guys . I enjoy the exchanges and the photos of situations that people share, and save them for examples to share with my staff.

Ain't that the truth! Misunderstandings, and time lapsing between replies - look at how much discussion would have been extraneous if we had known earlier that this was a deck.

But some of us obviously don't mind discussing tangential things anyway!

Thom, I was wondering about this statement:

As I stated before, the only difference between a balcony and a deck, from a structural standpoint, would be the live load that must be applied to the structure. Under the 2006 IBC there is a difference, however under the 2009 IBC the live load is equal to that of the occupancy that the deck/balcony serves, which would be the same in either case

It seems like if this case were a balcony, it would depend not only on the load, but where that load is distributed. Since the supports are not continuous through the wall, there's a pivot point at the bolt furthest from the wall, with the structure being held in place by the other bolt: perfect situation for the splitting Garry and Jerry M were talking about, since the forces are in opposite directions and would act like a pry bar. The force on the bolts would grow the further away the load was. So if you had 4 people standing 3 feet from the wall it may be safe, but not if the deck is 10 wide and they're at the railing.

Whereas with a post-and-beam deck, the load is of course distributed over more points, and it's also straight down along the whole length of the joist. So the bolts are sharing the load and the prying action stops, since the force on them is in the same direction.

Does that make sense? I'm just wondering if I'm thinking of it correctly.

Kristi,

As a cantilevered balcony the connection shown is most likely inadequate. The bolts attaching the new joists to the old ones need to develop what we engineers call a resisting moment couple, the prying action that you mentioned.

The IBC does not require you to check for any concentrated loading (except for the guardrail), just a uniform live load based on the occupancy of the main building, which in this case is 40 pound per square foot (psf), plus the dead load of the balcony itself.

If we assume the balcony cantilevers 5'-0", the joists are 16" o.c., and the dead load is 10 psf, the moment that the bolts must resist is:

(40psf + 10psf) x (1.33' o.c.) x (5') x (5'/2) = 831.25 ft-lbs

If the bolts are 12" apart, each bolt must resist:

(831.25 '#) / 1'-0" = 831.25#

Which is fairly substantial load for a single bolt to resist, so you would probably need 2 or 3 additional bolts to reduce the load to each bolt. The connection should definitely be designed by an engineer.

However, if there is are posts and a beam supporting the ends of the new joists away from the building, the load to the bolts is only from simple span loading (with no moment action), which is:

(40psf + 10psf) x 1.33' x (5'/2) = 166#, or 83# per bolt, which a 1/2" bolt carries easily.

These over-simplified calculations confirm what you are thinking, so yes, you are correct.

Thanks, Thom! Great answer, with the math and everything!

Chuck,

If I am looking at the picture correctly the deck joists are butted up against the wall and spliced to the stubs with bolts, then this is absolutely NOT acceptable. A bolted splice like that in a cantilevered configuration IMO is subject to sudden failure. Even if you propped the outer end that splice is still not allowed. I would red flag that as a dangerous condition and recommend nobody use it until replaced or strengthened properly.

Originally Posted by Thom Huggett

As a cantilevered balcony the connection shown is most likely inadequate. The bolts attaching the new joists to the old ones need to develop what we engineers call a resisting moment couple, the prying action that you mentioned.

If we assume the balcony cantilevers 5'-0", the joists are 16" o.c., and the dead load is 10 psf, the moment that the bolts must resist is:

(40psf + 10psf) x (1.33' o.c.) x (5') x (5'/2) = 831.25 ft-lbs

If the bolts are 12" apart, each bolt must resist:

(831.25 '#) / 1'-0" = 831.25#

Which is fairly substantial load for a single bolt to resist, so you would probably need 2 or 3 additional bolts to reduce the load to each bolt. The connection should definitely be designed by an engineer.

Sorry, Thom, but I'm confused--you computed a bending moment for a point where the cantilevers stub out of the existing foundation (using 5'/2 for the moment-arm, half the length of the 5' cantilever), but then equated that to a resisting moment-point midway between both of the bolts in each connection. Not quite realistic, is it? In that the centroid of the bolts is much closer to the point of load, meaning the actual bending moment at the bolts would be considerably less than what you're showing. But you completely ignored the moment applied by dead and live loads on the rest of the deck (beyond the cantilever) but not supported by the exterior columns. Meaning your numbers might not be too far off anyway.

P.S. Forgive my ignorance if I'm out of line, as I'm not a design engineer, having spent only 2 years "behind the board" before getting into field construction work more than 40 years ago.

As an aside, are we shooting for 200 posts on this topic?

BridgeMan,

I did mention that the calcs were "over-simplified", however most engineers will take the conservative approach that I took.

Randy,

The assumption was that the existing cut joists were of sound material. Another assumption must be that the bolts meet all end and edge spacing distances as required by the NDS (National Design Specification for Wood Construction) by the AF&PA. If that is also the case, this connection is, or could be made to be, code compliant.

Thom

That is a moment or bending splice, as far as I know there is no approved lap splice method for a bending or moment splice in wood.

I have a stake.... can somebody bring a hammer?

Randy,

I'm not sure what you mean by "approved", but most situations can be designed if not specifically disallowed by the code. A wood moment connection is not a very practical connection due to the geometry of the connection and size of the bolts necessary, nor would it be very reliable, especially exposed to the weather, but it is possible. The most common method for addressing this situation is to lap the joists along-side the existing joist back into the building, but I don't think that is possible in this situation.

I not sure this one is going to die very soon, Jerry.

Thom

If Jerry will hang on a little longer...

By approved I mean I can find no reference in the NDS or any other code that prescribes an acceptable "moment splice" design method for connecting two wood beams made from standard sawed lumber. There is an approved moment splice method to connect glu-lam beams cut for shipping but the splice is designed at the inflection point or the point of minimum moment. Extending a new joist back into the wall just replaces the original joist and a splice is no longer needed. At first I thought the new joist were cantilevered and supported by just bolting to the old joist, which is the location with the highest moment (worst case). If the new joists were also supported at the outer end with a beam then the splice would still have some moment to a lesser degree. There are a few other items concerning splices in general I wanted to share with home inspectors:

• A splice designed for one material like steel cannot be copied and applied to wood.
• There are four basic forces to consider in splice design in any material; bending, shear, tension and compression.
• The four basic forces listed typically change with location of the splice. For example a splice designed at mid span may be totally unacceptable if the same splice configuration was used on a splice over a support.

Jerry, you can drive the stake now.....

How about this to throw in the mix, I was inspecting stucco cracks yesterday morning and observed a cantalever galvanized steel beams supporting a balcony supporting a deck transferring re-actions through out the foundation and wall assemblies.

I have lost complete faith in the AHJ ability to inspect framing and cladding sytems, and with due respect to that code enforcement, they may not have taken out a permit

Originally Posted by Joseph Ehrhardt

How about this to throw in the mix, I was inspecting stucco cracks yesterday morning and observed a cantalever galvanized steel beams supporting a balcony supporting a deck transferring re-actions through out the foundation and wall assemblies.

I have lost complete faith in the AHJ ability to inspect framing and cladding sytems, and with due respect to that code enforcement, they may not have taken out a permit

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No Worries,

The Same Folks put up that Privacy Fence along the back parking lot.
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Joseph,

Looks like a retrofit job...maybe the deck joists were too springy when they finished construction so they added the steel framing to stiffen them up. Are the cracks due to flexing of the steel members due to loading or temperature fluxuations? Where are the cracks? The structural solution may be ok, depending on the sizing of the members and the attachment of the steel members at the lower level.

Sorry, I just couldn't let it go....

Randy, it seems like you've jumped into the conversation without reading previous posts. Since there are over 100 of them, I certainly don't blame you for that! However, it seems to me your first post in the thread gives an opinion based on little knowledge of the actual structure, since you apparently don't know whether it's supported elsewhere or not. I think this has been a common error in many of the posts in this thread. I simply don't see how it's possible to say much of anything concrete about the structural stability of the splice without knowing more about the deck.

BridgeMan and Randy,
Thom's post that showed calculations was in response to a question I posed about the forces that would come into play if the structure were a balcony vs. a deck. I don't think it was meant to be applied directly to this situation, since obviously there are assumptions and simplifications made.

And a couple questions:

What happens when something is built in a way that is not addressed by codes? If this were a splice everyone agreed was structurally sound, but it was neither accepted nor rejected by the codes or standards, would it be a problem?

I've brought this up a few times already, but no one has addressed it. Wouldn't the decking, if screwed into both old and new joists, add some stability to the splice?

All the theories in the world are meaningless on this thread as the posted photo is only a partial, we don’t know the current structural stability or current condition of the original cut-off cantilevered section, how the support beam was installed, length of deck projection, condition of the decking; therefore, debating whether the deck will support any loads imposed is meaningless and a waste of time. Don’t we all agree it needs a full evaluation by a competent SE? Please somebody, bring a sledge hammer!

Kristi

The section below is from the 2006 IRC and commentary. I think this address your question. IRC codes are prescriptive, as long as you follow them to the letter you should be fine. If you deviate from the code or have a situation that does not fit then the local code official (AHJ) has the authority to interpret the code. The AHJ can make the call to require an engineer's design and certification that it meets or exceeds the intent of the code. If a builder knows in advanced something is not going to be covered by code they can supply an engineer's certification or design up front for approval.

R301.1.3 Engineered design. When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. 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.

Commentary - Generally, proper application of the IRC requires a clear understanding of and adherence to its prescriptive limitations, which are based on conventional construction. However, a building may contain structural elements that are either unconventional or exceed the prescriptive limitations of the code. This is acceptable, if these elements are designed in accordance with accepted engineering practice by a design professional.

As to your last question about the deck boards adding strength to the deck. Individual deck boards laid perpendicular to the joist have no impact on the strength of the deck and for design purposes they are considered dead load. If the deck boards are laid at 45 degrees that can help stiffen the deck against lateral movement but would still be considered dead load for vertical load support. Wood design is not as exact as say steel or concrete design due to the fact no two boards have the exact same engineering properties. Factors such as moisture content, knots, growth ring spacing impact the strength of the lumber. To compensate engineering guidelines have large safety factors built into design formulas to account for all the unknown variables.

Jerry, what's wrong with discussing the theoretical? The whole thread was about the theoretical, for the reasons you point out. You had your say, why do you mind others discussing it? I, for one, am learning something by it.

Thanks, Randy! That was a great reply. Interesting that decking laid at a 45 degree angle to the joists help stiffen it. I can understand what you're saying about decking in general not adding strength, but speaking strictly from a theoretical and not a design standpoint it seems like joists that are flush together might be different. But anyway, it's a trivial little thing, I was just curious.

Kristi
I may be a firm believer in Epicureanism, but I ain’t no Lucretius.

Originally Posted by Jerry McCarthy

Kristi
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I may be a firm believer in Epicureanism, but I ain’t no Lucretius.

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Oh Yeah,

Well I Might Eat Hog but I ain't eating any Part that Walked,Talked, Heard or Processed Anything.
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