Reuben Saltzman

Coon Rapids Deck Collapse – Why It Happened

If you watched the news this weekend, you probably heard about the deck collapse that happened in Coon Rapids on Friday.  On WCCO news, they even had an expert speculate that the deck collapsed because it wasn’t properly secured to the house.  When I hear news stories about a deck collapses, they usually say they’ll come back to the story once they learn what the problem was, but they never do…

so I decided to inspect this Coon Rapids deck myself.  Here’s what I found:

Epic Fail

Coon Rapids Deck Collapse 1
According to WCCO, there were only five people on this deck when it collapsed.  The problem wasn’t that the deck was improperly attached to the house – this deck was completely missing a post.

I marked up two photos to show exactly what went wrong.  Click on the photos to get a large version.

Coon Rapids Deck Collapse Ledgerboard

Coon Rapids Deck Collapse Explanation

As you can see, one corner of the deck wasn’t help up by anything.  The floor joist that was closest to house is what was actually holding up that entire corner of the deck.  It’s a wonder this deck even supported it’s own weight.

While most advice about deck safety deals with proper bolts, nails, brackets, etc, it’s just as important to take a step back and look at the big picture.  Proper nails and bolts aren’t a substitute for a proper load path back to the ground.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minnesota Deck Inspections

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No responses to “Coon Rapids Deck Collapse – Why It Happened”

  1. American Home Inspector Directory
    July 18, 2010, 9:09 pm

    Great pictures Reuben,

    I have been a home inspector for 11+ years and in construction for 25 + years. I have built and inspected everything you can think of. But I did not build that deck! Hope nobody was hurt.

  2. Gary
    May 29, 2012, 7:59 am

    So how do we know that the house floor joist is not a doubled band/rim board? Requires a look inside, right? But even if it’s just a single joist at the house, it’s held up with a double plate stud wall beneath. So a properly attached, adjoining deck end-joist is unable to hold up the deck? Why? The lateral stress would pull that deck away from the house?

  3. Reuben Saltzman
    May 29, 2012, 7:19 pm

    That end joist was just nailed to the house, and that joist isn’t designed to hold up that beam.

  4. Gary
    May 29, 2012, 8:03 pm

    Just so. But IF that end joist of the deck was attached with PROPER fasteners, why would it fail? The parallel joist at the house does sit on a double plate that carries the weight to the ground thru the stud wall. Therefore, the assembly acts as a “post”, yes?

  5. skyjumper
    July 17, 2013, 2:35 pm

    in this case that end joist is being used as a second “pseudo ledger” to hold up that end of the deck. the beam holding up the whole outer portion of the deck attaches to that end joist at a point load, with no other support to hold it up. you can’t do that.

    a ledger functions to transfer a distributed load (by way of the distributed floor joists connected to it) to the house’s load bearing structure. But in this case the load was not distributed along that end joist (pseudo ledger) – it was all concentrated at the point where the beam attached to it. even the proper number of ledger bolts would not be enough to support that much weight at that single point. hence it fell – at that point. as is clearly visible in the photo.

    now you can argue all day long that if they had used 100 ledger bolts all around the beam connection then maybe it would’ve held up. but they didn’t, and that would be very poor construction practice anyway.

    even if they had extended the beam into the structure of the house so that it was supported directly by the load bearing wall — that would still be a code violation.
    The only way to properly build a deck like this is to support that corner with its own post, with the beam bearing directly on it for a continuous load path to ground.

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