This is a picture of my ceiling. I would like to hang a swing that will hold an adult.
I'm not constricted for space, so I could attach directly to one of the 2x2's
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5I-joists are complicated — you can’t just screw into them like you would with normal joists. We have some folks here with engineering expertise… hopefully they’ll see this. – Aloysius Defenestrate Mar 10 '24 at 14:37
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2You can do anything you want. Whether you should is entirely another matter... – Ian Kemp Mar 12 '24 at 09:11
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Would the swing axis be parallel to the beams, perpendicular, or some other orientation? The direction of loading matters! – Toby Speight Mar 14 '24 at 09:31
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What impact- and crush-resistant armour will the swinger be wearing? – Andrew Morton Mar 14 '24 at 17:55
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The answer with I-joists is always "ask the manufacturer." Your image's "Trus Joist TJI 210" is sufficient to figure out the manufacturer, Weyerhaeuser. Since there appears to be no blocking nor braces between your joists, the joists are vulnerable to side loading caused by the swing's dynamics. Your installation requires some kind of bracing between two joists at the minimum. It seems reasonable to impose on this bracing to also serve as the anchor point for the swing. That gives you much more freedom in locating the swing's exact position and solves the bracing problem all in one goo (sic). I wouldn't anchor to the I-joist itself. The fastener strength would be sensitive to whether or not you hit the notch at center, and the weight's local stresses on the glue joint around your anchor point would make me uneasy.
You should implement Detail H2 from their documentation:
Specifically, you want to implement the connection on the right twice, once for each end of a solid wood block between the two joists. If the joist is 9-1/2" tall, then you want 2x10 material for the block. 11-7/8" tall? Then you want 2x12 material. It's important that the top edge of this block gets installed as close as possible to the underside of the floor sheathing, but something like a 1/4" gap is still good enough. It's important that this block fits tightly in between the two joists with minimal gap at its ends. Perfectly tight is ideal (not so tight that it's bulling the joist out of the way), but maybe a 1/16" gap is good enough. A gap here has a good chance of squeaking. Many people would install 3 blocks in line with each other, installing the swing to the center block. Given quantities of material that you'll probably be stuck buying, the additional 2 blocks would probably just cost extra labor.
LUS26 joist hangers are the most popular on the market, and those will work fine for joist hangers. You don't need tall ones or anything.
For the backer block sizing and installation I'll put the screenshot from their docs:
Your joists fall under the 210 column, where I assume you have 9-1/2" or 11-7/8" joists. In that case, your backer blocks (you need a total of 4 of them) should be 3/4" OSB or plywood. Footnote 1 recommends 12" long backer blocks, where you cut them just tall enough to fit between the top and bottom 2x2s. A bit of a gap between the top 2x2 and the backer blocks is encouraged to prevent people from damaging the joists by beating the backer blocks into position. You want it bearing on top of the lower 2x2, though. 15-0.131"x3" nails per joist to secure each pair of backer blocks.
The "clinch nails when possible" from footnote 2 means to bend over any nail points that poke through the other side. The 0.131"x3" nails are also perfect for toe nailing through the joist hangers. They would stab through the joist by an extra inch or so, but you might just use the same nails everywhere. Clinched nails are stronger, so you'd only be improving strength by using the too-long nails.
popham
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"That gives you much more freedom in locating the swing's exact position and solves the bracing problem all in one goo (sic)". I'm missing where anyone mentions 'goo'. What do you mean? – MackM Mar 11 '24 at 15:03
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3@MackM, it was my typo, and I like it. Giving a brace double-duty against a gravity load is impure in an engineering sense. "In one goo" criticizes the pattern. The "sic" is so that a well intentioned editor doesn't correct it. – popham Mar 11 '24 at 16:31
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1'Goo' is also yam-yam (Black Country) for 'go', Black Country being in the Midlands, U.K. – Tim Mar 12 '24 at 15:26
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Hanging a swing from overhead joists was done on porches, at least it is shown in mid 20th century movies. To implement now it seems it requires an expert understanding of modern contruction, significant materials, and expert installation. – Jim Stewart Mar 14 '24 at 15:05
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A quick hack would be to screw a full 4'x8' panel of 3/4" OSB to the ceiling running perpendicular to the joists. That's for 16" spaced joists like yours appear to be. Instinctively I would want something like 7/8" OSB for joists spaced at 24", but I can't source that material in my locality. I can source 1-1/8" plywood sheathing, but that's getting heavy and expensive for a "quick hack." You can hang the swing from the 3/4" OSB panel. The side loading has to rack 5 or 6 joists in parallel instead of just the one. As the joists rack sideways there's some extra stiffening from the OSB panel as the racking tries to deform the panel into a wavy shape.
Fasten the panel to the ceiling with 2" screws every 8". For hanging the swing, just bolt a bracket to the panel before hanging it. Something like this D-ring anchor would work nicely.
I would install the bracket at about the 1/4 point between 2 joists (1/4 times the 16" spacing to get a 4" offset from a joist) to instinctively maximize stiffness. Nothing rational about the 1/4 spacing, just a guess.
popham
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Out of curiosity, any reason to prefer a 4'x8' sheet over something like 4-2"x4"s or 3-2"x6"s? – UnhandledExcepSean Mar 12 '24 at 19:06
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@Unhandled, just erring on the side of caution, and the OSB panel better fits the basement's engineered wood motif. The joists have a lateral-torsional-buckling failure mode that side loading will aggravate, so I want the ratio of side load demand over side load capacity as small as possible. For your detail, my quick number is 170# side load capacity versus my side load capacity of something like 460#. For a quick upper bound on the side load demand (assuming 200#, 6 ft swing radius, maximum speed at top of the swinging arc, and max height of 3 ft above the low position), I get 170#. – popham Mar 12 '24 at 22:05
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@Unhandled, of course the speed at the top of the swinging arc is zero. My guess is that the real side load in that scenario is somewhere between 30% and 50% of the 170#. 60#/170# = 35% in your case makes me a little uneasy. Taking the upper bound in mine, the 170#460# = 37% makes me uncomfortable also, but I've toyed enough with the numbers around swings that my 30% to 50% intuition puts my mind at ease. – popham Mar 12 '24 at 22:05
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@Unhandled, I could really geek out on it and probably rationalize your sawn lumber by putting it at an optimal spacing and treating the joist bottom flanges as horizontally oriented beams, counting on them to spread the load around from the 2x4s to a longer length of joist web, but this is a quick hack. – popham Mar 12 '24 at 22:06
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@Unhandled, I mispoke. It's a flexural-torsional buckling mode, not a lateral-torsional buckling mode – popham Mar 12 '24 at 22:17
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For sure you can ask people who know about structural wood to advise whether any one attachment point is strong enough. Answers on here already cover that part.
For a suspension hard point though, you should not be looking at a single point of attachment. The relevant people to ask are climbers or anyone else working at height with harnesses. Best practice is for there to be 3 anchor points, going to the carabiner or other fitting from which your swing will be attached. You can build all this in with thin metal cables spreading the load.
It is acceptable for one anchor point to be the main one; but the other two must be able to take the shock load if the main anchor point fails and they have to catch it.
Your method of attaching to beams also needs to be considered. Wood screws are not generally advisable. Best practice is to put bolts through, with suitable plates on each side (or at the very least wide washers) spreading the load over the surfaces of the beam.
Toby Speight
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Graham
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Having three anchor points would prevent the hanging chair from being much of a "swing", for better or for worse. On the other hand, it would be good to have a support structure that distributes loading over a length of beam rather than concentrating it at any point. With regard to redundant supports, I'd be inclined to use bungies whose elastic range would extend far enough for the swing to reach the floor. but with enough resistance to prevent any normal static load from reaching the floor. If the primary support fails, having the bungees absorb most of the potential energy... – supercat Mar 12 '24 at 15:51
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...from the swing's occupant before the occupant reaches the floor would avert injury, and having bungees that reach the floor would ensure that they would be able to absorb energy without failing. – supercat Mar 12 '24 at 15:52
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3Life-critical safety practices for an indoor swing sound like a lot to me. I would put a rug under if it I was worried. – MackM Mar 12 '24 at 15:55
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@supercat If you've got two hanging points for the swing, you'd either put a bar across from your single hardpoint; or (better) you'd rig two hardpoints and hang both sides of the swing on that. Swings don't have redundancy - either side failing will dump you on the floor, so allow for that. (And I'm strongly suspecting "swing" is the SE-acceptable version of "tied-up person", but I'm not going to ask and they don't have to tell me.) – Graham Mar 12 '24 at 18:59
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@MackM If you're not worried about being dumped directly on your coccyx or lower spine on a solid floor from 1m up, then you don't know enough about spinal injuries to make an informed decision yourself or advise anyone else. Life-critical, no. Walking-ever-again-critical? Very much possible. Unable-to-walk-properly-for-3-months-critical? Most likely outcome. Don't mess about with this kind of stuff. – Graham Mar 12 '24 at 19:10
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@Graham This was my thought exactly. Modeling the anchoring of the whole assembly to the ceiling separately from the anchoring of the seat to its pivot point. The "bar" to which you refer. I think it would be preferable to have the entire assembly mounted to the ceiling with 3-4 hard points, and then you have your bar as the pivot point with two ropes, cables, or chains for allowing the seat to swing freely. – Tripp Kinetics Mar 13 '24 at 18:43
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1@MackM Rug isn't a great idea. There are padding solutions rated for mitigating falls of various types. – Tripp Kinetics Mar 13 '24 at 19:04
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(Recreational) climbing is very different to (regulated) Working At Height. Ask anyone who does rope access work. – Toby Speight Mar 14 '24 at 09:35
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@TobySpeight For recreational climbing and leading/seconding, sure. Nuts and quickdraws prioritise speed and getting some security, over getting the best security. But if you're setting up a top rope or an abseil, then you should still be hooking up your belay to three hard points. That's how I was taught anyway. – Graham Mar 14 '24 at 09:58
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Oh, we were just talking about selection of anchors - that aspect's the same. I was getting distracted by irrelevant differences (dynamic ropes, twin-rope systems and the rest). Sorry for the noise! – Toby Speight Mar 14 '24 at 13:48
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@TobySpeight It's a fair point. If the OP was looking at people being able to land on their feet, then they wouldn't need that level of caution. It'd be over-specced for a rope swing over a lake. :) – Graham Mar 14 '24 at 14:14