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I'm investigating the possibility of hanging a pull-up bar/ rock-climbing training board from the concrete ceiling in my apartment. The slab is 180mm (7inches) thick and the (static) weight which I would need to support would be 70-90kg (155-200lb). My ceiling is also my neighbour's floor, the building is from 1958... I've read similar questions and responses here and the the issue seems to be tensile strength of the concrete. Originally I planned to use two expanding bolts and an epoxy to help secure them but now I'm not sure.

My question is: would adhering fibreglass sheets to the ceiling where I place the bolts help to improve the ceiling's tensile strength and reduce the chance of the concrete cracking/failing?

If I did this I imagine I would first drill the holes for the bolts, then glue fibreglass sheeting over the whole area, and then pierce the sheet just over the holes in order to place the bolts. Is this a terrible idea? A free-standing structure is not an option - it's ceiling or nothing.

EDIT: Seems like the general consensus on the fibreglass is it wouldn't help. Can anyone suggest an alternative method of safely anchoring the load to the ceiling if money was no object and I wanted to seriously over-engineer this setup? Distributing the load over a wider surface with 2x4 and/or marine ply or similiar and using that as an anchor etc?

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Warning: for a pull-up bar, you do NOT need to just support 200lb. You need to support the dynamic load of grabbing the bar, hanging from it, swinging from it, etc. This works out to many times the static load; I don't know the conversion, but 5x may be a starting point. –  Alex Feinman Oct 23 '12 at 17:29
    
Thanks Alex. I had considered that as well. This is the product I was considering using:ramset.com.au/Product/Detail/82/DynaBolt-Plus-Sleeve-Anchors It has these specs: Max Tensile 2.7kN -16.6kN Max Shear 2.5kN - 15.6kN –  Nic the climber Oct 23 '12 at 17:32
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To answer your edit, if money is no option, build a large mansion and have an engineer design a room in that mansion with the proper structural support for hanging objects from the ceiling. Move into the mansion. Forget about trying to use your current home for purposes it was never designed to handle. –  BMitch Oct 24 '12 at 2:39
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Thanks BMitch. What colour do you think I should paint the mansion? –  Nic the climber Oct 24 '12 at 4:48
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I've been told the correct color is "whatever your wife picks" –  BMitch Oct 24 '12 at 14:31

8 Answers 8

Stop and think for a moment. What are the consequences of the ceiling FAILING because you drilled holes in it and hung weights from those holes? Is it possible that the ceiling may fail catastrophically? You're also weakening the upstairs neighbor's floor, which may at times be very near its design limits. What happens if you're hanging from one point while a very heavy person rolls a refrigerator across the upstairs floor directly above you?

Don't do this thing.

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All you need is 4 3/8" drop-in anchors. We support transformers from the concrete ceiling in electrical rooms all the time. The manufacturer for the drop-in anchor has specifications for exactly how many thousands of pounds each bolt can handle. The fiberglass idea and epoxy ideas are terrible. Concrete gets stronger when it is old, so you don't have to worry about it being old.

You will need a SDS hammer drill to make the hole. Make sure you make it the proper size.

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A company that makes them is called Powers.com –  somebody who knows Feb 18 at 18:38
    
if the concrete is 3000psi strength then you can hang up to 1090lbs from one 3/8" drop-in anchor. Thats the shear strength of only one anchor, so 4 of them would be 4360lbs. –  somebody who knows Feb 18 at 18:40

Use 3/8" x 5" wedge-all anchors to put up a piece of unistrut 2/3's longer than your bar. Put your anchors in every 5 inches, hang the bar form the unistrut. We hang ceiling lifts this way to pick up bariatric patients.

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The correct answer here is to not hang the load from points on the ceiling, which will damage the structure and could make you liable for losses due to the damage, but to build a structure that will spread the load on the floor. (I think this was covered in a few previous questions... I'm certain I've given this answer before) You would want to build a structure out of steel, either angle iron or square tube, with legs that will spread your weight load across the floor. Many structures are available pre-made, even ones that fold up flat, for crossfit enthusiasts, or you can always manufacture your own with metal, an angle grinder, and a drill and bolts.

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Personally I would not even begin to attempt to hang athletic equipment from a concrete ceiling. That said there are reasonable ways to do this in a safe way. There are commercial / industrial anchors that should be used for this type of application. The best ones are insertable bolt studs that are glued into the hole with special epoxy. If you were to use this approach I would be selecting fasteners that penetrated as far up into the 7" ceiling thickness as possible.

A quick search on the web with epoxy concrete fasterners will provide a plethora of information.

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You could use lag shields. There are 3/8" ones available that spec out at 3300 lbs/anchor. You can find more information here.

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Gluing fiberglass to the ceiling will not help anything. This is like nailing something to a wall through wallpaper. Does the wallpaper make the nail any stronger? No.

The tensile strength of the concrete is also not the concern. (Concrete is generally assumed to have zero tensile strength, anyway.) The load on the concrete ceiling is not really significant—it's basically the same as if you were standing (or jumping) on the floor from above. The issue is going to be sure that you get an anchor that will not pull out or break off a chunk of concrete around it. This is probably going to be specified by the anchor manufacturer (possibly with several values, depending on the strength of the concrete).

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No matter what you do, the load will be relying on the strength of the bond on a surface that is no larger than the surface area around the diameter of the fastener. a few square inches. This is friction and maybe shear strength of a thin chemical bond, not compression strength.

I do not know the math, but an overhead load approaching 1000 lbs relying on the diameter of a few bolts sounds scary.

Unless someone (manufacturer or contributor here) can give you a firm test strength that exceeds 500lbs per fastener when pulled straight out, I would avoid it.

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I'm starting to get the idea that this won't work in the manner I had envisioned. Would there be any alternative ways to still anchor the load to the ceiling? i.e. fixing a 2x4 with several expansion bolts + epoxy and then using that as an anchor to help distribute the load etc. (moderators: not sure if this constitutes a new question or not. Please let me know if I'm posting in the wrong place) –  Nic the climber Oct 24 '12 at 2:16
    
Distributing the load over multiple anchors is a good idea. Be sure you are truly distributing the load though. The proper placement of the connections on the distributing member is critical. The 32MPa concrete in the anchor spec is fairly good quality, you should probably assume half that to be safe. It really comes down to the quality of the concrete. Even the smallest hairline cracks nearby could completely kill the idea. –  bcworkz Oct 24 '12 at 4:08

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