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Deck


Tom Breslawski

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I don't know why you'd write up the cleats, or the screws in the cleats, or anything associated with them. The cleats aren't doing anything all. And their use even violates a basic rule of mechanical design.

You have two load paths of wildly different stiffnesses. One load from the beam and through the bolted connection to the post, then to the ground. That load path is very stiff. It's where all of the load is going. The load path from the beam through the cleat, through the screws, and into the post is extremely flimsy, even if you can install it in such a way that the cleat was originally able to take some load from the beam (which you can't). So that load path isn't taking any significant amount of load because it's so elastic.

It's a basic rule that you shouldn't have two load paths really at all, but especially if these two load paths have such different stiffnesses. Because you always want to know where the load is going, and you can't know that with two load paths of different stiffnesses. But in this case the load path through the cleat is clearly so flexible that the cleat is just window dressing and can be ignored.

Also, I know it's wrong according to the deck rules, but as far as I can tell no deck has ever failed because this type of bolted connection failed. If anybody knows of such a failure I'd love to hear about it.

A lot of poorly built things last a long time.

Some who know me accuse me of being a pedant.

It helps, S. to read the OP. The "cleats" were incidental to the OP. Around here they are installed on roof trusses to meet "positive connection" code req's. They are to resist uplift from winds.

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I don't know why you'd write up the cleats, or the screws in the cleats, or anything associated with them. The cleats aren't doing anything all. And their use even violates a basic rule of mechanical design.

You have two load paths of wildly different stiffnesses. One load from the beam and through the bolted connection to the post, then to the ground. That load path is very stiff. It's where all of the load is going. The load path from the beam through the cleat, through the screws, and into the post is extremely flimsy, even if you can install it in such a way that the cleat was originally able to take some load from the beam (which you can't). So that load path isn't taking any significant amount of load because it's so elastic.

It's a basic rule that you shouldn't have two load paths really at all, but especially if these two load paths have such different stiffnesses. Because you always want to know where the load is going, and you can't know that with two load paths of different stiffnesses. But in this case the load path through the cleat is clearly so flexible that the cleat is just window dressing and can be ignored.

Also, I know it's wrong according to the deck rules, but as far as I can tell no deck has ever failed because this type of bolted connection failed. If anybody knows of such a failure I'd love to hear about it.

A lot of poorly built things last a long time.

Some who know me accuse me of being a pedant.

It helps, S. to read the OP. The "cleats" were incidental to the OP. Around here they are installed on roof trusses to meet "positive connection" code req's. They are to resist uplift from winds.

Yes, there was a whole lot of problems with that deck. Were the cleats the worst? Nope. But they were still wrong. Throw them in with the other things that were wrong and the chances for a failure increase.

I'm was paid to find things that are wrong, or could go wrong. As Jim said, a lot of poorly built things last a long time. I just don't want to be the one that tells them that something is ok when it's not.

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It helps, S. to read the OP. The "cleats" were incidental to the OP.

The OP starts like this:

"The 2x4 cleats on these 4x4 posts are attached with deck screws. Is that ok?"

So how can you possibly say that the cleats were incidental to the OP? From my reading the cleats were the entire point of the OP. And the cleats aren't wrong; they're entirely useless.

My point about the bolted connection is that not everything that's wrong is equally bad. Of all the things that a homeowner has to fix and maintain, fixing something that's never going to fail should be pretty low on the priority list.

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It helps, S. to read the OP. The "cleats" were incidental to the OP.

The OP starts like this:

"The 2x4 cleats on these 4x4 posts are attached with deck screws. Is that ok?"

So how can you possibly say that the cleats were incidental to the OP? From my reading the cleats were the entire point of the OP. And the cleats aren't wrong; they're entirely useless.

My point about the bolted connection is that not everything that's wrong is equally bad. Of all the things that a homeowner has to fix and maintain, fixing something that's never going to fail should be pretty low on the priority list.

The cleats were incidental when looking at the entire deck. Yes, they were the subject of the OP, but they were just one more problem to list with the deck.

Just because it's lower on the priority list doesn't mean that it shouldn't be in the report.

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My bad, S. Having followed the thread I already forgot that terminology. 2Xs nailed to the side of a post to me are just "scabs" or something The thread drifted to the little simpson tie-downs...I see 2Xs cut nailed to the sides of block piers now and then when layout errors make the girder miss the pier.

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I don't know why you'd write up the cleats, or the screws in the cleats, or anything associated with them. The cleats aren't doing anything all. And their use even violates a basic rule of mechanical design.

You have two load paths of wildly different stiffnesses. One load from the beam and through the bolted connection to the post, then to the ground. That load path is very stiff. It's where all of the load is going. The load path from the beam through the cleat, through the screws, and into the post is extremely flimsy, even if you can install it in such a way that the cleat was originally able to take some load from the beam (which you can't). So that load path isn't taking any significant amount of load because it's so elastic.

It's a basic rule that you shouldn't have two load paths really at all, but especially if these two load paths have such different stiffnesses. Because you always want to know where the load is going, and you can't know that with two load paths of different stiffnesses. But in this case the load path through the cleat is clearly so flexible that the cleat is just window dressing and can be ignored.

Also, I know it's wrong according to the deck rules, but as far as I can tell no deck has ever failed because this type of bolted connection failed. If anybody knows of such a failure I'd love to hear about it.

Maybe I missed it, where did he say or where do you see "bolted" connections?

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Maybe I missed it, where did he say or where do you see "bolted" connections?

In the original post picture, the 4x4 posts are bolted to the double 2x6 girders, which aren't likely to go anywhere unless someone herds elephants onto the deck.

When that happens, the silly 2x4 cleats might possibly come into play, but I doubt it.

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if the cleats are not flashed, couldn't they hold water at that intersection? Couldn't that water contribute to rot? Maybe even corrode the bolt. Could it fail?

Likely I would not have reported them.

"...castles, made of sand,

melt into the sea,

eventually..."---Jimi Hendrix

Yet another reason I like Baird! He gets me.

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The design principle that was beat into me about 50 years ago is that you locate assemblies and sub assemblies with details - not with fasteners. And fasteners should be loaded in their preferential mode - nails should be loaded in shear, bolt/nut combinations or machine screws primarily in tension etc.

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