Cloud absorber attachment that doesn't trash isolation

[saemola]

Hello everybody,

I'm about to put up two cloud absorbers in my studio.
After reading dozens of threads I still couldn't find the answer to this apparently simple questions: how do I attach my clouds without destroying my isolation?

I'm gonna put up two clouds: one is meant for high frequency absorption only so it will pretty much be mineral wool in a light frame; the other is going to have a hard back 2cm|3/4" MDF board to break standing waves, which means it's going to be weight 30kg!

My ceiling is made of two layers of 1,5cm drywall. Can I attach the clouds in places where there are no studs? I was thinking of using some "toggle bolts" like these: https://www.amazon.com/Hillman-370054-T ... B000BD8MFQ

These require pre-drilling a hole, so I was thinking I would drill the hole, insert the screw, caulk in abundance, tighten the screw.
Will this trash my isolation?
Are there better/easier/faster/isolation friendly alternatives out there?

[Soundman2020]

Don't hang stuff from drywall alone! Only attach into the joists. It's not safe to rely on drywall to hold things up like that. Drill into the joists, and use heavy-duty closed-loop mounting hardware, always. In other words, no hooks that remain as hooks. Also, make sure that all your mounting hardware is rated for at least ten times the weight of the object. So if your cloud will weight 30 kg, make sure you use hardware that is rated for 300kg. That's a general rule of thumb for stage rigging, and applies here too: You don't want heavy stuff above your head suddenly coming down ON your head!


- Stuart -

[saemola]

Don't hang stuff from drywall alone! Only attach into the joists. It's not safe to rely on drywall to hold things up like that. Drill into the joists, and use heavy-duty closed-loop mounting hardware, always. In other words, no hooks that remain as hooks. Also, make sure that all your mounting hardware is rated for at least ten times the weight of the object. So if your cloud will weight 30 kg, make sure you use hardware that is rated for 300kg. That's a general rule of thumb for stage rigging, and applies here too: You don't want heavy stuff above your head suddenly coming down ON your head!


- Stuart -

Thank you Stuart!
Does that also count for “soft” clouds? As in, clouds without a hard back, meant for high frequency absorption only. Those should be pretty light.
I’m absolutely committed to safety, that’s why I want to find the right hardware for this. Do you have specific pieces you would suggest?
I thought the hardware I linked was meant specifically for drilling into joists and holding heavy weights (they come in different size/strength)

But my question still stands: how do I not trash my isolation? Do I drill holes which I then caulk?

[Soundman2020]

I thought the hardware I linked was meant specifically for drilling into joists and holding heavy weights (they come in different size/strength)

Nope. Toggle-bolts are meant for mounting directly through drywall alone, and are only meant for walls, not ceilings. Note what the manufacturer says about those. "... are intended for anchoring into hollow walls. ". My emphasis. Not meant for ceilings. In walls, the weight of the attached object is pulling mostly vertically down the wall, in the same plane as the wall, and drywall is reasonably strong in that direction. If you used them on the ceiling, then all the weight is trying to pull perpendicular to the surface, and drywall is NOT strong on that direction.

But my question still stands: how do I not trash my isolation? Do I drill holes which I then caulk?

If you screw your mounting hardware into the joists, then it's exactly the same as screwing or nailing the drywall to the joists! No difference. The shank of the bolt or screw completely fills the hole. Yes, it's a good idea to put caulk in the hole before you screw in the hardware, just to be safe and get the best seal possible.

Do you have specific pieces you would suggest?

I would use screw eyes, preferably forged (not wire-formed). Depending on the type, eight 5/16" screw eyes 3" long should probably be about right for a 30kg load. Just one of them could actually support the load, but the 10x safety factor is important. Each one of those should likely be rated for a load of 100 pounds (about 45 kg).

I'd then use light chain with a similar rating to actually hang the cloud. No open hooks! Use locking carabiners.

This is one area where I believe in "overkill". I don't like things hanging over my head that aren't supported properly. Do some research on theatrical rigging and stage rigging, to see how it should be done safely.

- Stuart -

[saemola]

This is one area where I believe in "overkill". I don't like things hanging over my head that aren't supported properly.

No doubt about that!

Since English is not my main language, I’m using Google Image to help me with the hardware you are pointing me to.
I understand the locking carabiners, but the screw eyes?

This is a 5/16”, 4” screw. How do I drill this into the ceiling AND the steel joists? Looks like it must be driven by hand! If I drill a hole before inserting it then it will have nothing to “bite” into.
But most importantly: how does it hold onto the joist? It doesn’t have a “butterfly” mechanism like the hardware I linked in the first post, where the screw opens up once inserted. It surely can’t simply hang by the thread on the shaft... can it?
That does sound scary to me.

Thank you Stewart!

[Soundman2020]

I didn't realize that you have steel joists: I was assuming they were wood.

If they are steel, then I'd use eye bolts (similar to screw eyes, but threaded bolt shank, not screw shank). If you have access from above, then just drill the hole a little larger, caulk it as you put the bolt through, then put the nuts and washers on from the top. If you do not have access from above, then drill the hole a little smaller than the bolt, and cut a thread into it to match the thread on the eye bolt. I'm assuming that your steel joists are thick enough for this: the steel would have to be at least as thick as the correct nut for the eye bolt. Use a washer and two lock nuts below the drywall, to lock the bolt in place. And of course, caulk the hole here too, just to be sure.


- Stuart -

[Gregwor]

the steel would have to be at least as thick as the correct nut for the eye bolt.

To get the maximum strength, you need to have as much thread as the diameter of the bolt. Ex: a 1/4" bolt requires 1/4" depth into a nut or material. Smaller than 1/4" bolts use a number system. Here's a chart showing the thread diameter for those:

[saemola]

Thank you so much for your help guys, this is all very clear now.
It kinda blows my mind that simply drilling a thread the size of the eye bolt is enough to keep everything in place considering I don’t have access from above.

The size of the joists doesn’t seem to be a problem since they are about 5cm wide.

Do you think that in order to hang a set of acoustic hangers I would still need to come up with a system anchored to the still joists given the hangers’ light weight?
I was thinking otherwise I could simply hang two parallel joists into the drywall by screwing every 60cm and hang the hangers onto those.

[Gregwor]

It kinda blows my mind that simply drilling a thread the size of the eye bolt is enough to keep everything in place considering I don’t have access from above.

You need to tap the hole after you drill it in order to create the threads.

Do you think that in order to hang a set of acoustic hangers I would still need to come up with a system anchored to the still joists given the hangers’ light weight?

Yes. No matter what, anchor your clouds via your ceiling joist.

I was thinking otherwise I could simply hang two parallel joists into the drywall by screwing every 60cm and hang the hangers onto those.

You don't only have to worry about the integrity of the drywall where your anchor penetrates it, you have to think about how that drywall is anchored to the joists above it. It's mounted using crappy little drywall screws with heads smaller than... well... you know what I'm saying.

Don't question this. It's a for your own safety.

Greg

[saemola]

Don't question this. It's a for your own safety.

Not at all. Just trying to understand.

Could you clarify what you mean by “you need to tap it”?
Again, English is not my main language.

[Soundman2020]

The drill bit does not create any thread inside the hole: it just makes the hole. You use a "tap" to cut the thread into the sides of the hole. That's why you must drill the hole SMALLER than the size of the bolt: so there is enough metal to "tap the hole", and create the thread.

A tap is similar to a die, and they usually come in sets. The "die" is used to cut the thread on the outside of the bolt shaft: you don't need that, because when you buy the bolt it already has the threads. The "tap" does the opposite: it cuts the threads on the inside of the hole

This is what taps and dies look like:

tap-and-die_SML.jpg

The circulars one that look like very thick coins with a hole in the middle are "dies", for cutting threads on steel bar that has no threads. The cylindrical ones that look a sort of like a drill bit, but with parts missing up the sides, are "taps".

They usually come in sets of several different sizes, like this:

tap-and-die-set_ENH.jpg

The long things with handles on the ends are what you use to hold the tap or die while you cut the thread. You do this by hand, NOT using an electric drill! You do it slowly, a little at a time then backing off, then a little more and backing off, so that the metal you cut away does not clog the thread you are forming.

If you have never used a tap before, get someone who does know to teach you how, or better still, to do it for you.

- Stuart -

[saemola]

Thank you so much for all the great info guys.
I have everything that I need to get this done now!

[saemola]

Guys, if I may, I have an extra question:
how large would you make the acoustic hangers?
I have a 3.4m tall room (roughly 11 feet).
Should I use the 1.85x0.5 JLS formula, or should I go bigger (especially taller since I they can be almost twice as tall)?