Suspension from ceilling...

[Peter Purr]

I need to hang something from a single point on a ceiling. The load will be about 300Kg max, after allowing a suitable safety factor (actual load closer to 100Kg).

Any ideas or caveats?

I meant to look for a joist tonight in an out of the way location (probably a cupboard), make a hole in the ceiling there & have a prod about, as I'm not sure how much variation there is in possible structure, but the battery's flat in my stud detector, so that'll have to wait until tomorrow.

FWIW This concerns a flat in the middle storey of a small three storey block, which was built in the 1970s. I won't have access to the floor above, as that's obviously someone else's flat.

[Phil L]

Yes, forget it!

You can't do it without using steel, and to do that you'd have to do it from above, even then it's not reccomended....the load would have to be spread over 3 or 4 joists, you'd have to place a steel plate on top of the joists (chisel the tops of the joists out to accomodate the steel plate under the floorboards) and bolt a long threaded bar down to hang your 'whatever' on...the nut would have to be below the level of the floorboards too.

What are you going to hang from a ceiling that weighs 200lb+?

[Colin Wilson]

My money's on a sex swing...

[The3rd Earl Of Derby]

Mines on a sandfilled punch bag.

[Brian]

something from anne summers or clone zone! very odd.

[Peter Purr]

Hmm, if you had a liking for snuff you could combine the two, but even I'm not that sick. It's an armchair - though I don't know if that's the right term as it doesn't really have arms. As to sex, not sure, though I imagine the swinging is the reason for a safety factor of three.

So does everyone so far agree with Phil, that it can't be done?

How about going at this from the other direction? What loads can safely be suspended from ceiling joists for various fixing methods?

[Peter Purr]

I had to Google for clone zone. Oh dear, I think I'm spotting a pattern in replies ;(

Can anyone offer informed comment on the problem itself?

[The Natural Philosopher]

I don't think thats a huge problem.

You would have to hack the plasterboard etc out a bit, but a couple of bolts through the beam will be plenty strong enough,

Its the beam deflection that worries me.

1/3 ton is not too bad on a 6x3 beam over a few feet...but it will sag.

[John Rumm]

You are talking about a 1 to 3kN imposed point load which is quite a bit

- especially as you have no control over what load will be placed on top of the ceiling (i.e. in the flat above).

I expect it owuld be simpler to make up a steel frame/gantry that would rest on your floor and carry the load.

To make any stab at an answer we would need to know the joist width and depth, the span, and where along the span you wanted the load fitted. For example, close to a supporting wall at the end of a joist may be doable. The middle of a room is unlikely to be easy.

[Peter Purr]

Is that safe? I assume so from your suggestion. I'd read going through the centre of the beam is acceptable, but not above or below due to the compression/tension.

Understood.

Thanks for the comments. I'll get some measurements tomorrow hopefully which will make the options clearer.

[The Natural Philosopher]

Well sort of yes.

Find out how big your beams are, and how long, then buy one and get some mates to lift the chair onto some supports roped to it, and sit in it.

That will tell you how much its going to affect your ceiling...

[Peter Purr]

I'm keeping that in mind as a last resort, but without some pretty creative design it could look hideous which SWMBO wouldn't wear & in any case she's the one who wanted the fecking thing - I just get to make it happen.

That's what I expected. I'll try to get this info tomorrow if I have time & get to prod about.

Understood. No figures yet, but it wouldn't be at an end - probably four to six feet away. Also, one of the walls is internal - it has the boiler behind it - not that I know if that's likely to correlate with a supporting wall or not; I'll have to check that out too. Thanks for the comments.

[Peter Purr]

Wouldn't any deflection increase over time, or do you think most/all would be immediately apparent?

[dom]

I would expect a 1970's flat to have decent fire protection between flats/floors - more than plasterboard/joists/floorboards. Are you sure there isn't concrete in there somewhere?

[Codswallop]

Might be worth checking with your insurance company whether you are covered should you go ahead and cause structural damage to the building. Your policy may not cover diy disasters.

[dcbwhaley]

And checking the terms of the lease

[tinnews]

I fixed a hanging chair in my daughter's room a few years ago. It simply hung on a plate screwed to a joist. There were no problems with deflection - i.e. the ceiling didn't develop any cracks. The main problem was with fatigue failure of the screws as it was very difficult to get the whole thing stiff enough so that they didn't flex. It did last for a year or more at a time before the screws needed replacing (or one broke_ though.

[Roger Mills]

All but one of the replies so far have assumed that you have a wooden structure - but it's worth checking whether this is *actually* the case. If the building was purpose built as flats - as opposed to built as a house and subsequently converted into flats - there's at least a chance that there's concrete between the floors. Does your flat have a wooden floor, or is it solid? If solid, then the one above will also be solid - in which case you should be able - with suitable fixings - to screw an eye bolt into it from which to hang your chair.

If the structure is wooden, you'll need to spread the load over several joists. A large steel plate, attached to several joists with 100mm long 10mm diameter carriage screws would probably do the job. Or if you don't mind taking the ceiling down, you could bolt some hangers through the centreline of several joists, and then bolt your plate to the hangers.

[Codswallop]

It crossed my mind that it could be a concrete construction. If so, would the presence of steel reinforcing rods need to be considered if drilling into the ceiling to fix an eye bolt? SWMBO may not have thought this through.

[Peter Purr]

Thanks, that's useful to know, though I doubt your daughter weighed sixteen and a half stone - I suppose I could always put up a sign next to it stating only for thin guests.

Cheers,