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At a corner of my house I have a two-level wrap around deck. It is not far off the ground, 2-3ft. One level is about a foot above the other.

This question is about the lower level. It is 15.5 feet long, but it only contacts the house along a 3.5 feet-long ledger board.

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This hot tub deck connects with the upper deck in only one location, 8 ft out from the house. That connection seems to be pretty weak.

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All posts supporting the hot tub deck underneath tilt away from the house a bit.

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While the posts are tilted, the distance between the upper and lower decks is the same in all places, which makes me think that either the posts were tilted from the beginning, or the tilting is the result of ground moving underneath. (But the ground would not move uniformly to tilt all the posts, would it?)

Is this something of concern? Anything that should be done about it?

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The lean in the posts roughly corresponds to what we see as gaps in the connection between the decks and the curve in the rim joist there. I agree that this is a concern considering the massive load of water.

Depending on the other deck for position isn't the right approach. I would be installing diagonal bracing to rigidly hold position. Random, arbitrary connections won't do much, especially with a short deck where leverage is at a premium. You need targeted support to specifically address the movement we see here.

You have several options to do this:

  • Lumber or strapping across the underside of the deck beams
  • Strapping above the beams and under the joists
  • Strapping over the joists and under the decking
  • Lumber between the posts on the lower deck (not ideal due to their short lengths)

Ultimately it'll look something like this:

enter image description here

image source

Note that non-rigid bracing must be installed in both directions, whereas lumber can be used in just one. Of course, the decking itself lends a lot of diagonal support. Read on...

You'll need to first square up the deck. This is probably best done by pulling the longer diagonal from above--right rear to front left in the final photos. A hand winch (come-along) or large ratchet straps might do this effectively, or pull to a nearby tree. Then set your bracing. You might go a bit beyond square to allow for settle-back.

Whatever your solution, strive to get as close to 45° angles as possible with your bracing. Extremely long angles don't work as well.

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  • For squaring up the deck - where should I attach the hand winch or the straps? Commented Jun 29, 2023 at 16:43
  • Right at the corner, however is convenient. You can wrap supporting straps around the assembly or install temporary lag screws. Use caution as there will be substantial force involved.
    – isherwood
    Commented Jun 29, 2023 at 16:45
  • The assumption here is that there is no movement on the further side from the deck, where it is attached to the house, right? That attachment seems to be pretty weak as well - the ledger board is attached using nails, and I am not sure what it is attached to inside the house. Commented Jun 29, 2023 at 16:47
  • Regarding bracing options - are there standard names or pictures of this you could point to? I am having hard time picturing each option :) Commented Jun 29, 2023 at 16:48
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I wouldn't be concerned about the connection between the two decks. It was never intended to be structural. I'd add the missing joist hanger. Considering the weight of the hot tub, I would be concerned about the tilting posts. Correcting the tilt doesn't have an easy fix, expecially if the beams, such as that 4x8, have a twist. I'd be inclined to reframe it, making the hottub support independent of the deck.

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  • The hottub has its own support - separate posts and separate beams. But they are also tilting. Commented Jun 29, 2023 at 6:24
  • Yeah, I would think about trying to plumb the leaning posts and installing some diagonal struts to keep them plumb-er. Maybe use heavy duty ratchet straps to draw it toward the other deck?
    – Huesmann
    Commented Jun 29, 2023 at 13:00
  • I agree with your opening statement, but not the rest. There is a fairly easy fix, and the decking itself lends a lot of diagonal support.
    – isherwood
    Commented Jun 29, 2023 at 13:52
  • If "MorganTheFreeMan" is the same person as the "free" who wrote this answer, then you need to get your accounts merged so you can edit your own posts. At a minimum, log back in on the same machine/browser where you wrote this answer as the cookies will allow you to edit it.
    – FreeMan
    Commented Jun 30, 2023 at 11:30
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You asked another question about attaching stair stringers. When that is done while not structural, it will help tie the 2 decks together.

If all the 4x4 posts of the lower deck are aligned, I would tie them together front to rear to help against tilting further. If they are not I would put blocking between the beams. Basically tie all the support structure together under the joists.

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