This is probably a bad idea.

I think you need to specify what you're hanging. If it's meant to be hung and it's that heavy, it should come with instructions. If it doesn't, it probably shouldn't be hung.

Is this a first floor room in a two story? Is it a room just under the roof? What kind of framing is above the ceiling?

If the framing above the ceiling is the 2x4 bottom chord of a roof truss, don't do this. Just don't .

It is a two story house and this is in the upper floor. I am not sure what type of framing it is but here is a picture of it: https://ibb.co/xGXxs2Q

The red circle is where I plan to add the eye hook from beneath.

The purple markings in this picture is where I was planning to lay the 4x4 or the 2x4. The plan was to have the eye hook hanging from the 4x4/2x4 and not the ceiling trusses. The 4x4/2x4 would lay on top of the joists where the drywall is fixed to. Here is the picture: https://ibb.co/HtN6QvF

Does this make sense? I don't want to do anything that is not safe, that's why I am checking before even starting. Any help is appreciated.

Edit to say:
My plan is to lay the 4x4/2x4 on top of the joists, not at all connected directly to the roof structure (sorry for the bad drawing). Once laid down, I would put the insulation on top of it again. It would be flush with the ceiling just above the joists.

Realistically it would be around 350lb but I am calculating 500lb as a safety margin. Instructions say to hang it to just one joist. I am being more conservative and planning to fix to a 4x4/2x4 over several joists to spread the load.

You might be right and I don't want to be that person that does what wasn't supposed to be done. That's why I am double checking before even starting. :-)

From the pic it looks like all the weight will be supported by the two 2x4s that you intend to span with the new 2x2 or 4x4. I don’t think the question is which material you should use. The question seems to be “are those four anchor points on the two trusses strong enough to support another 500 lbs?”

I can't tell from any of the pictures if your roof/ceiling system has 2x4 bottom chord or not. Again, if what's under the insulation is 2x4s, don't do this. Not with a 4x4, not at all.

Based on your answer I got the impression that the drawing I did is so bad that it might be giving the wrong impression on where I plan to lay the 4x4/2x4.

My plan is to lay it on top of the joists, not at all connected directly to the roof structure. Once laid down, I would put the insulation on top of it again. It would be flush with the ceiling.

Does it make sense? If not, what "four anchor points on the two trusses" are you referring to?

That would make me nervous. Ceiling joists are usually just 2x4 trusses, maybe 2x6 at most. Not meant to carry heavy point loads and especially not in a single 500 lb weight.

Would be mildly better if it was closer to a wall than in the middle of the room.

If you must do it, don’t just place a 2x4 or even 4x4 across the top of the joists. The hole to connect to that would be difficult to seal properly.

I would build an inverted-T shape the same depth as the joist. The part between the joists is a 4x4 (or whatever height of the joists) and gets attached through the sides of the joists with proper construction screws. Then a longer piece of 2x4 is laid flat across the top of the insert and across at least 2-3 joist on either side and screwed into any wood it’s going over.

Drill a hole through the assembly into the room below. Insert proper eye-bolt (rated for 600lb or more) with a washer and nut on top to secure it.

I believe this is the type of roof I have: https://ibb.co/NrBks8n

I know for a fact that the joists where the drywall ceiling is hanging from are 2x4's.

You aren't "calculating". You are "guessing". There IS a calculation you can make which determines what the effective maximum load of a swinging weight is.

I would spend a little time looking this up, or maybe pay an engineer 50 bucks for an hour of math.

Yes, it's 2x4 joists. It is close to the outside wall and another internal wall but the internal wall is just aluminium framing and I don't think it plays any structure role in it.

I am trying to understand what you proposed. Doing some research. Thanks.

I think I understand what the plan is. I just cant tell how the joists are fixed to the studs or rafters (having a hard time with the perspective). All I can see are the metal plates that, I assume, are just reinforcements. So then I am asking how are they fixed tot their crossmembers? If they are strong enough to support the weight then my next thought is how long of a span is that? If it’s several feet then I would not want to center it on the joists. The final question is “after unstallation, what if someone were to hang on it? Would it still hold?” I’m kinda imagining you’re looking to install a heavy bag.

That metal is just the framing from the underneath drywall work. Not structural at all.

I am not sure how long is the span because of all the insulation but based on the portion I was able too see I have an impression it's pretty long.

I will try to take better pictures to see if it helps.

Then don't hang anything more that the drywall that's already there. Engineered trusses are not designed to carry any floor load. They are designed only to carry the roof, and any expected snow load.

If you're considering modifying your trusses, you'll need to have a licensed engineer design the changes.

And they aren't joists. They're the bottom chord of the engineered trusses.

Seriously-- 2x4s aren't even included on span charts. Without a stamped engineer's drawing being followed, they don't carry weight when they're horizontal.

Got it. So let's say you are right and it's not joists it's the bottom chord of the engineered roof trusses. Would that mean you can't put any load on it? I am genuinely asking because I know people walk on top of it in attics. If someone were to hang from the bottom of it (across more than one), wouldn't it be the same?

It's your house...you can do as you please.

But this is wrong...dangerous, and foolish. No disrespect intended.

That roof structure was designed to do its name "ROOF STRUCTURE" - ala hold up the roof...the roofing, the insulation, etc. and carry those loads over to load bearing walls. That's called 'dead load'.

Now anyone with half a brain knows that service people walk across those all day long...that's called live load.

Generally some safety factor is used because people do stupid things in homes...but 'stacking weight' equivalent to two people at a point load is hazardous.

All beams deflect under load...so if you 'attempt' this recognize that your beams will deflect and apply forces greatest at the point of the load...the idea to spread the weight out across trusses is a prudent one (albeit foolhardy) - whatever beam you select it will apply the most force to the two closest and the least farther away. Which means a lot of loading at two points NOT DESIGNED to carry those loads.

Among other loads...are 'new roofing' (often 2nd layers of roofing are laid atop the old) - perhaps you already have tile...or composite...really irrelevant to additional loads only if a 'change' were to take place...also snow/ice/water loading...as well as wind and seismic loading.

So while it may 'hold it' it may not hold it under ALL situations and scenarios for which the structure was designed to perform...ala NOT COLLAPSE ON YOU when the 'weird' happens...such as some fatter service techs walking around...while there's snow/ice on the roof AND a car just ran into the building. So adding another 550-600 pounds (don't forget the members and attachment materials all add weight too)...or when an earthquake happens...or high winds.

Someone touched on in the comments the fact of the potential of a 'swinging load'...which is SIGNIFICANTLY greater than static loads.

MY ADVICE is to consult a STRUCTUAL ENGINEER - some calculations are beyond the 'simple calculators' which can be found online...there's more to structural engineering than just a 'beam loading calc'.

Edit: To include: That even your wall cladding (ala drywall or plaster) could also crack...not only do beams deflect but so do the walls that are under those roof pressures. Drywall isn't flexible...nor is plaster...so you may also have surface problems to deal with.

Edit2: I suspect you're wanting to hang a person...I hope in some sort of romantic/intimate manner and not permanently. I would recommend you transfer loads to the floor. As you didn't say what you'd like to hang...there are few things 350ish pounds that I can surmise beyond 'a person' (bsdm I presume). Reading comments you're on the 2nd floor with this weight...which adds to the center of gravity situations. You can reinforce the trusses too...remembering that the more cross sectional area the 'stronger' your reinforcing becomes. Best would be to calculate the deflection and have spacers on the trusses to allow for uniform loading with deflection. Without knowing what you're hanging - and for how long would determine how best to plan...a 'person' wouldn't be full time loading (I hope not anyway) - but still 'weird stuff happens' at unusual and unplanned moments. Also to consider...that home is designed to 'stay up' (for as long as it can) during a fire event...where loading would worsen that situation.

Edit3: A typical house is designed to carry 40 psf (pounds per square feet) live load...but that's on the floor. I believe rooves are 10 psf - but don't quote me...and WHY you should consult a structural engineer.

It would be the same, in that a 2x4 bottom chord of an engineered truss is not designed to carry any live load other than the roof load. A person hanging from a 2x4 risks breaking the 2x4, because by themselves, 2x4s are not structural.

https://i.imgur.com/NfdnTrR.jpg

First pic is the blocking, second is the board running over the blocking and joists with the bolt poking through the assembly.

You certainly can apply load, it’s just not intended. The trusses form triangles so the snow load and wind uplift are actually causing tension and compression along the length of that bottom chord of the truss. Either pushing or pulling along the length based on the downward or upward pressure. That’s how they can get away with using a “little” 2x4. It’s not direct downward pressure like you get on a 2x8 or 2x10 floor joist (that is just a straight across board and no diagonals) from a load standing on top of it.

I think he’s safe if he spreads the load across several joist. Plenty of people (me included) have many hundreds of pounds hanging from the garage trusses.

The risk is likely not breaking, but rather slight movement that can cause cracks in the drywall.

They're not joists. Joists are structural, 2x4s are not. It really is that simple. When running horizontally, there is no span chart for a 2x4.

Technically, that’s correct, they’re part of the truss assembly. The bottom chord.

A quick Google search does find plenty of results for span tables that includes 2x4’s though.

Span charts for 10 pounds per square foot. Not really walkable. And at 30 psf, the 2x4s disappear from the chart.

Thank you very much for all your insights and detailed response. I really appreciate it.

Based on the comments in this thread and after confirming the type of roof I have, I gave up going ahead with this idea. It might be able to support it ok but I do not want to find out.

Someone suggested to transfer the load to the floor. One option I could see would be to support the 4x4/2x4 on two opposite walls in the room. I know the walls use metal studs and I assume it would need to lay on top of stud post that goes to the floor, not between studs. Anyway, I am giving up this idea for now.

By the way, the plan was to hang a Hammock Chair like this which would not be bearing the load 24x7. I also liked the "romantic/intimate" swing idea.... LOL.

Got it. Thanks for your thoughts on this.

Based on the comments in this thread and after confirming the type of roof I have, I gave up going ahead with this idea. It might be able to support it ok but I do not want to find out.

By the way, the plan was to hang a Hammock Chair like this which would not be bearing the load 24x7.

Thanks!

https://www.homedepot.com/b/Outdoors-Patio-Furniture-Hammocks-Hammock-Stands/Chair/N-5yc1vZbxb8Z1z17mfj

The more you spread out the weight the better. BUT if it's only for a chair...then I wouldn't even begin to worry about this.

As I said...work men are able to walk across single trusses without 'damaging' the structure or loading. Therefore YOU 'sitting in a chair' is the same 'live load' for the area.

I WOULD do as you initially planned and span 4-5 trusses...use a beam calculator to determine the amount of deflection you'll get at each distance and use spacers/shims so you get equal loading to each beam. I'm 220# and walk across standard roof trusses with wild abandon...on one foot supporting all my loading. As I suspect you're equally heavy - and adding for chair and support you still probably wouldn't break a truss...but swing loading is different than static loading. So yeah...span 4 trusses have the outside trusses with like 1/2" spacers and the two closer ones with 1/4" spacers - that'll help spread out the load. As it's a chair it's presumed you wouldn't be loading it at the same time workers are also 'up there' (either roof or attic). Edit: Actually use a beam calculator to determine the correct deflection distances from the load - don't just run with the 1/2 - 1/4 I plucked out of no where. The closer you position to other vertical members the better - as everything 'works together' as a system.

Of course a hammock stand to the floor would 'spread out' the weight better...as that's got plywood as a load distributor instead of drywall - so you get more spread out loading instead of point loading.

I suspected it was a hammock chair...but it's more fun to be 'kinky' about it...but have also heard silly things like someone wanting to suspend fish tanks because 'it would look cool' - without realizing how much a lot of water actually weighs (and bodies being mostly water).

Anywhere you can spread out the load and transfer it more evenly to the ground is ideal.

I still would consult an engineer...only because were you to damage the home...or structurally impact it you'd need to declare (full disclosure) that in a home sale and/or insurance claim. Stamped calcs would clear you of 'reckless damage' (and other legal/financial risks).

As I said another option would be to stiffen up the existing trusses...usually done with slapping 3/4" ply on either side and through bolting (sandwiching the member). Stiffening won't 'solve' all the problems but will help transfer the loads to the walls and limit deflection.

Common safety factor is 2x and always plan for the worst...ala the potential of two people climbing in...the nicer thing about a stand is it becomes the sacrificial lamb instead of your ceiling/roof structure. You're unlikely going to cave in a floor any more than you would when two people hug/stand in the same spot.

Still engineering calcs would solve a lot of problems. I'd call one and find out the fee for it - it may be way less than you're suspecting - and determine how best to proceed. If the calcs cost more than a stand, get a stand...or if that would ruin your aesthetic and/or not fit in the ceiling height.

Giving up isn't a 'solution'...impossible only happens when you give up. You've got this...some things are worth the effort. Good luck and you're welcome.

Edit: I was the one that suggested transferring loading to the floor btw.

Thank you for the info and the words of encouragement. Yes, I would still prefer to have it hanging than have it on floor. It allows me to put on or take it off to store it away when not in use. And of course, could also be used for other (kinky) applications, which is a bonus. ;-)

With that said, I'll see if I can find an engineer for such small job to reassure everything is ok.

Thanks again.