Joist hangers on both sides of deck?
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I’m building a floating (no ledger board on house) deck on a slope with a buddy and we did not make either side cantilevered. One side is a grade level beam and the other is sitting on 4×4 posts 30” off the ground. We were going to hang the joists on each beam using joist hangers. Any issues with this? It was a misunderstanding when we set it up but figured most decks use joist hangers on the ledger side anyway so they need to be able to carry the load. Any structural issues we should be concerned about? Thanks in advance – just subscribed and this entire catalog of info is incredible.
Replies
Without the ledger board to secure and stiffen the deck, you have to make sure that your 30 inch high 4x4 posts are secured, so that the whole deck does not twist or slide down the hill.
what size is the deck, and what size are the beams you plan to use?
what is the frost depth in your area? are you digging footers for the support points?
You can use joist hangers, but it probably would be cheaper to plan to place the joists so they sit on top of the beams. This way also removes any concern on the load being placed on only one side of the beam.
Yep we’ve dug footers and built the beams already. I wish I would’ve subscribed to this 1-2 weeks earlier cause it would’ve saved a lot of issues later. The deck is 14x8 with (2) 2x10 beams and 2x10 joists 16” OC. We dug 6 footers - 3 on each side 7ft apart. How could I prevent the twist? By running a diagonal bracing from corner to corner or just blocking would prevent twist?
I think the use of the word floating threw me off. Looks like you have the beams secured to the ground. (not resting on the ground)
the deck should hold together ok. be sure to use enough of the hanger mounting holes. don't skimp on the proper nails.
The decking should keep the assembly from twisting.
You might want to consider structural elements that make triangles with the posts to make sure they stay vertical.
Study this: https://www.awc.org/codes-standards/publications/dca6
This is incredibly helpful - thanks!
The prescriptive guide assumes the deck is tied to a house.
generally, but there is guidance for the beams for a non-ledger deck and guidance for the lateral-load braces, the main elements that would need to be addressed for a free-standing deck. Not to mention a lot of other details he would seem to be interested in addressing.
Of course, you are correct. but even the non-ledger deck described uses attachment to the house for lateral support.
The guide figure 10 describes use of diagonal bracing on outside posts parallel to the beam. Without attachment to the house, he also needs diagonal braces at right angles to the beam. The layout of this deck will let the joists help anchor the beam on top of the posts from falling over, but a diagonal brace would be a good element to include, it seems. I want to guess that the holes on the sides of the joist hangers are designed to keep the joist setting in the hanger, not to transfer lateral loads.
Also probably needs a railing on that side, since it seems this side is over 30 inches tall.
The mismatch in the application does not mean the info in the guide is not good, but that if an inspector showed up, he would not be driven to approve due to compliance with the guide.
8' wide deck is a little narrow. I've found for smaller spaces, every available inch makes the space more functional. If the deck height is not critical, I'd consider using longer joists and cantilever over the beams.
2x10 joists for an 8' span is overdoing it a bit. 2x6 will meet code for that span, 2x8 will give a stiff deck.