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I have wooden I-beams in my basement ceiling that support the floor above (see attached picture), and I want to hang a 100 lb sandbag from these I-beams. As far as I can tell, the beams are made of some type of pressure-treated engineered wood. I found the specs online; what is not clear is how the loads are meant to be applied. That is, a load pushing down on a flange from the top is different from a load pulling on a flange from the bottom.

I-beams in ceiling

The question I have is - what is the best way to approach this mount?

Some options I have considered:

  • Directly attach the mount to the bottom flange, by drilling right into the center. The mount came with two 1/2" screws. The concern here: I am not sure how wide the web is, and once loaded I am worried that the screw will just rip out, even if it is going through the flange. Plus, can the flange take the load at all?

  • Rig up a mount with a 4x4 across two I-beams. The 4x4 would sit on the flange, and be attached to the web with anchors to keep it from moving around. The concern with this approach: is the I-beam designed to take a load like that? That is, something pushing down on the flange and away from the web. In this case I would be worried about ripping the flange off the web.

  • Rig up a mount again, this time with two sheets of plywood on either side of the web (essentially to take the "I" out of the I beam). Do this for two adjacent I-beams, and then affix a 4x4 to the plywood. The idea here is if I am pushing down on the flange from the inside, I am distributing the load over a much longer extent. Maybe a little better than option 2?

Any thoughts? This is the first time I've tried something like this; I really don't want to bring the ceiling/floor down or set myself up for a very expensive repair.

isherwood
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StackMonkey
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3 Answers3

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This is not a complete answer, and you should contact customer support / technical support for the maker of your joists but here is a hint at how to go about hanging things (in this case, another joist) from the sides of joists from one manufacturer. Sandwich the web in blocking with LOTS (tens) of fasteners and hang from the top flange and blocks. That's not for hanging a bag but you could take guidance from it.

enter image description here

Elsewhere in those instructions you'll find guidance on blocking --- also, not for your application but you can take guidance from that and use blocking between several adjacent joists for lateral support if your bag is going to be swinging or treated with abuse.

You can also spread the load between those several joists.

jay613
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  • This is the right solution. It's how loads are connected in a construction scenario. – isherwood May 25 '23 at 14:54
  • @isherwood those instructions say to use 3 inch nails as fasteners, clearly intended to protrude far past the opposite side. I'm curious, do you know why shorter, say 2 inch, nails are incorrect to fasten material that is about 1.75 inches thick in total? – jay613 May 25 '23 at 14:59
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    They want to be sure that the nails protrude a sufficient distance on the backside. They hold much better that way. The same is true of roofing nails. – isherwood May 25 '23 at 15:02
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    Also, shorter nails are likely to be of smaller diameter, which results in less grip and stiffness. 2" x .131 are probably not common. – isherwood May 25 '23 at 15:05
  • Thank you for this. I will reach out to the manufacturer; hopefully they can get back to me with some ideas. – StackMonkey May 26 '23 at 11:06
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    Remember, "live load", not "punching bag". You may get the quick brush-off with the latter. :) – isherwood May 26 '23 at 13:06
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You mentioned a sandbag, I am assuming that it's a punching bag or similar, and it will sway.

When I did this with a boxing punching bag and roof trusses, the weight was not the problem. The problem was the swaying of the bag. Beams and trusses are not designed for that sort of load.

So, I would suggest that you need to brace the beams to take lateral force in addition to fastening them towards the top.

Rohit Gupta
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Your engineered joists are meant to handle loads pressing down from the floor above, which place the top of the joist in compression. You are right to be concerned about adding a load to the bottom of a joist, which would place the member in tension and could lead to failure.

Is there any way to attach your sandbag to the top of the joist, preferably at multiple points?

Phil Freedenberg
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  • Thank you Phil for the response. I can try drilling into the side of the top flanges, maybe? The floor sits right on top of the joists, so I don’t think I can get between the joist and the floor. – StackMonkey May 25 '23 at 01:23
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    There's no answer here. This should have been a comment. – isherwood May 25 '23 at 14:53