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Weak Deck

In a house I just bought, I was having 3/4" hardwood installed. They staged at least 2,000lb of material on the rear deck. The deck was enclosed underneath with more stone veneer so I couldn't see the conditions of support. I commented I was worried about the load, the workers said "it will be fine" and jumped up and down and "see, it's solid". I got the load moved pretty quickly. Fast forward 3 weeks, I finally got the wall under the deck open. Glad I moved the load. Improper ledger attachment, actually can't see the connections, on the surface of brick veneer with no intermediate column support, improper joist support, concentrated load from double joists supporting an exterior stone veneer fireplace surround. And those are just the problems with the gravity load. Frankly surprised it survived. Deck repair/replacement on the horizon!

Rant...a little of topic but....
The fireplace is a wood burning unit, on a framed in and covered wood deck and roof. No hearth extension unless you count the 5/4 decking. I had a company come out to see about converting it to gas logs. In our conversation I asked if they would secure the permit. They said they didn't need a permit. I asked him if he knew why whoever did this thought it was a good idea to put a wood burning fireplace on a combustible floor with no hearth extension over a completely enclosed crawlspace blocking several house foundation vents on a deck that violates almost every prescriptive code in the book.. He said no. I said it was because they weren't required to get effing permits.
 
Reason #267 why Canadian decks require 6x6 posts. We got this white crap that falls from the sky and hangs around for a while.... and that white crap can get kinda heavy, esp. if it rains a bit ....
 
Inspector Gadget said:
Reason #267 why Canadian decks require 6x6 posts. We got this white crap that falls from the sky and hangs around for a while.... and that white crap can get kinda heavy, esp. if it rains a bit ....
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I've never seen a deck collapse because the columns were too slender and buckled. They always fail at the ledger or connections.
 
redeyedfly said:
I've never seen a deck collapse because the columns were too slender and buckled. They always fail at the ledger or connections.
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The 6x6 requirement in Canadian codes come from issues with 4x4 not being able to resist the necessary lateral loads in every wind zone in Canada. 4x4s can only be used where calculations show them to be acceptable.
 
jar546 said:
Nothing is "always" and when you live in high wind areas, the deck to house connection is just as important as uplift.
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The original statement is a good example of a hasty generalization logical fallacy, as the sample the analysis is taken from (their experience) is not adequate to come to the conclusion that it could not be an issue.
 
tmurray said:
The 6x6 requirement in Canadian codes come from issues with 4x4 not being able to resist the necessary lateral loads in every wind zone in Canada. 4x4s can only be used where calculations show them to be acceptable.
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How are the posts loaded with wind? I've also never seen a moment connection on a deck post.
 
jar546 said:
It has nothing to do with the size of the posts and everything to do with the connection of the posts at the base and the deck framing.
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That's a connection. I'm confused. My post was saying I've never seen a deck fail because a 4x4 post buckled and specifically said they fail at connections. How does a 6x6 solve this uplift connection problem?
 
tmurray said:
The original statement is a good example of a hasty generalization logical fallacy, as the sample the analysis is taken from (their experience) is not adequate to come to the conclusion that it could not be an issue.
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Providing ones professional experience is not a logical fallacy. The post literally started with "I've never seen" to qualify it as my experience. I'm also questioning it as a structural engineer because it is difficult to design a deck where the posts would overload a 4x4. They would have to be very tall.
 
redeyedfly said:
Providing ones professional experience is not a logical fallacy. The post literally started with "I've never seen" to qualify it as my experience. I'm also questioning it as a structural engineer because it is difficult to design a deck where the posts would overload a 4x4. They would have to be very tall.
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redeyedfly said:
... They always fail at the ledger or connections.
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There. That is the logical fallacy. You used your experience (professional or not) to come to a conclusion based on a very small sample size. Deck don't "always" fail at the ledger or connections. You may have poorly worded this to mean that you have only seen them fail in this way, but that is not what you actually wrote, nor is it the way I or Jeff took it.
 
redeyedfly said:
How are the posts loaded with wind? I've also never seen a moment connection on a deck post.
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These findings came from the National Research Council of Canada that provides code development research services to Codes Canada. They investigated a number of residential deck failures and found the columns were undersized to deal with the bending stresses of the lateral wind loads.
 
tmurray said:
There. That is the logical fallacy. You used your experience (professional or not) to come to a conclusion based on a very small sample size. Deck don't "always" fail at the ledger or connections. You may have poorly worded this to mean that you have only seen them fail in this way, but that is not what you actually wrote, nor is it the way I or Jeff took it.
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Dude, reading comprehension is not your thing. The one's I've seen or heard about fail at connections or ledgers. Sorry you guys have a hard time understanding written words.
I've also seen a lot of people call out logical fallacies when there isn't one.
 
tmurray said:
These findings came from the National Research Council of Canada that provides code development research services to Codes Canada. They investigated a number of residential deck failures and found the columns were undersized to deal with the bending stresses of the lateral wind loads.
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Cool story but how are they loaded by wind? Where are these bending stresses coming from? A typical deck post (certainly a prescriptively designed one) has a pinned connection at the top and bottom, no bending stresses from first order effects. The only bending is from p-delta effects which are from vertical gravity loading. Where are these findings? How are posts getting loaded by wind?
 
redeyedfly said:
That's a connection. I'm confused. My post was saying I've never seen a deck fail because a 4x4 post buckled and specifically said they fail at connections. How does a 6x6 solve this uplift connection problem?
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I never discussed the size of the post, nor made any reference to the size of the posts. Your post was about failure at the ledger connection, and I was adding information that there are other factors, such as uplift, that can cause failure of a deck.
 
redeyedfly said:
Dude, reading comprehension is not your thing. The one's I've seen or heard about fail at connections or ledgers. Sorry you guys have a hard time understanding written words.
I've also seen a lot of people call out logical fallacies when there isn't one.
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Sorry, I've clearly touched a nerve based on how emotionally charged your response was. I was simply pointing to where I saw the exaggeration of the evidence you had in coming to your conclusion. I genuinely did not intend to make you so upset.

redeyedfly said:
Cool story but how are they loaded by wind? Where are these bending stresses coming from? A typical deck post (certainly a prescriptively designed one) has a pinned connection at the top and bottom, no bending stresses from first order effects. The only bending is from p-delta effects which are from vertical gravity loading. Where are these findings? How are posts getting loaded by wind?
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I wasn't part of the code development system when that research was done, so while I am familiar with the basics, I do not have all the details. If you would like further information you may wish to contact NRC at info@nrc-cnrc.gc.ca for their analysis.
 
jar546 said:
I never discussed the size of the post, nor made any reference to the size of the posts. Your post was about failure at the ledger connection, and I was adding information that there are other factors, such as uplift, that can cause failure of a deck.
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My post was 100% about how decks don't typically fail because of posts buckling. I'm still confused as to what you're objecting.
 
tmurray said:
Sorry, I've clearly touched a nerve based on how emotionally charged your response was. I was simply pointing to where I saw the exaggeration of the evidence you had in coming to your conclusion. I genuinely did not intend to make you so upset.


I wasn't part of the code development system when that research was done, so while I am familiar with the basics, I do not have all the details. If you would like further information you may wish to contact NRC at info@nrc-cnrc.gc.ca for their analysis.
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oh my, so upset over here sipping my latte.

If you were part of the development you should be able to answer this very simple question. How does wind load a deck post? That is as basic as it gets.
 
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