Why does everyone use OSB behind drywall?

[JoakimJohansson]

The salning is what sits between, for example, the window frame and the trim/moulding.

Inserting panels doesn't sound realistic.

Aha okay!!
No, I didn't think so at first either but in just a few places of course it can be done...

 

[Mikael_L]

No opinion about boards behind gypsum but one thing is for sure, a hard material is not suitable for soundproofing, hard materials are never used where you want to reduce the risk of disturbing noise. The most effect is achieved with insulation in the wall.

Now I just want to gently point out that you're off track.
I think you seem to be mixing up acoustics and soundproofing, among others.
(That is, reflection and transmission.)

 

[Yrrol]

Sound experts say that different materials capture different sound waves. Therefore, it's good to combine different materials. Gypsum is not the super-duper magical best, it's just that it's cheap and what people are used to.

Even a brick wall can conduct sound...
An extra sheet of something is not everything; sealing all joints around sockets and other things is something you must not miss if you want to block sound between walls. Suddenly, it becomes very expensive for the carpenters to stand and glue each sheet, etc.
I've done some specializations in my rooms after a long time of reading on home theater forums and elsewhere.

You'll have to discuss with your partner whether special screws or regular screws with plugs are so bothersome that 50,000 is worth it. Or if a trip / bathroom furnishings / film projector, or something else weighs more.

 

[cecar33]

Now I just want to gently point out that you're barking up the wrong tree. I think you seem to be mixing up acoustics and sound insulation, among other things. (That is, reflection and transmission.)

No, I've just been out with the dog:wow:
A wall made of sheet material with insulation is significantly more soundproof than a wall with double sheets and an empty space in between. Additionally, there is a greater chance that it will be more sealed at penetrations since the insulation is there.

 

[Boan]

Okay, but then you only do it behind the TV, hat shelves, etc., where you know you will hang heavier things?
Because doing whole walls sounds like a lot of work?

Did whole walls. Not too bad. Battens all around. Then suitably sized mirrors. Just need to get the depth right on the battens.

 

[Mikael_L]

No, I've only been out with the dog:wow:

Of course, I'm not cycling now in the winter either...

A wall of sheet material with insulation is significantly more soundproof than a wall with double sheets and an empty space in between. Additionally, there is a greater chance that it becomes tighter at penetrations since the insulation is there.

Hmm, do you have any source on that? Or a calculation or theoretical argument?

It might also depend on what I mean by insulation, I'm thinking of mineral wool of normal density for insulation of a framed exterior wall, lambda approx. 0.036 -0.037.

 

[Yrrol]

No, I've just been out with the dog:wow:
A wall made of panel material with insulation is significantly more sound-absorbing than a wall with double panels and an empty space between. Moreover, there's a better chance it will be tighter around fittings because the insulation is there.

To be really nerdy, the insulation shouldn't fill the entire depth; ideally, there should be an air gap too.

Then regarding hat shelves and such.
So, the plugs you use can support (tension = ceiling, vertical = wall)
Single plasterboard: M5 & M6 in tension = 51 kg
Single plasterboard: M5 & M6 vertical = 132 kg
Double plasterboard: M5 & M6 in tension = 86 kg
Double plasterboard: M5 & M6 vertical = 268 kg
Single plasterboard: M8 & M10 in tension = 51 kg
Single plasterboard: M8 & M10 vertical = 174 kg
Double plasterboard: M8 & M10 in tension = 100 kg
Double plasterboard: M8 & M10 vertical = 290 kg

How often do you put up something that weighs more than 174 kg? Today's TVs or hat shelves are nowhere near that.
It would probably be the sink in the bathroom, where there's a risk someone might sit on it.
But where you know fixed installations will be, you put a board behind the plasterboard, inside the wall.

Njaaaaa...

 

[Mikael_L]

A wall made of sheet material with insulation is significantly more soundproof than a wall with double sheets and an empty space between.

Gyproc, for example, does not share the same opinion:
http://www.gyproc.se/konstruktioner/innerväggar/innerväggar+med+trästomme/ljudgran+gt+600

 

[Boan]

Okay, but then you only do it, for example, behind the TV, hat racks, etc., where you know you're going to put up heavier things?
Because doing whole walls sounds like a lot of work?

Did whole walls. Not too bad. Battens all around. Then suitably sized mirrors. The important thing is to get the depth of the battens just right.

 

[Nyfniken]

How often does one put up something that weighs more than 100kg?

Now it's actually torque and dynamic loads that are being calculated. In any case, our hat rack protrudes more than it is supported against the wall. Imagine an extreme case with a hat rack with 4x longer overhang than the support surface against the wall. Then 100 kg has suddenly become 25. A hanger with a 5 kg load that is hung up a bit carelessly, or someone who trips over the shoe pile and uses the hat rack for support is not unreasonable either.

 

[Mikael_L]

So I've put OSB + drywall everywhere.

It's not too difficult with drywall mollys, but it's really nice to avoid them anyway. A good molly, correctly installed in single drywall, can handle a very high force, more than many people think. And in double drywall, it becomes so strong that you rarely need more.

But well... If you miss the installation a little, it becomes immediately extremely difficult to try to insert a new molly a cm next to it. And if you change your mind or move things, something that looks like glued fifty-cent coins remains on the walls here and there. And even though molly is quite good and fairly simple, it's even easier and better with a screw of the right size straight into the OSB/particle board/plywood panel behind.

Then I also thought about getting better sound-insulated walls, but as it is right now, I gain nothing since our internal doors are of the simplest internal door type, i.e., sound class 30dB, so we gain nothing because of better walls. Also, a rubber seal would be needed in the door frame, as well as sound-dampened air transfer ventilation, to improve the sound class if I buy better doors. So there are many things connected there...

Unfortunately, it should never be easy...

 

[FredrikR]

If you want to be really nerdy, the insulation shouldn't cover the entire depth, ideally, there should be an air gap as well.


Then regarding hat shelves and other things.
So, the plugs you insert can bear
(pull-out = ceiling, vertical = wall)
Single drywall: M5 & M6 in pull-out = 51 kg
Single drywall: M5 & M6 vertical = 132 kg
Double drywall: M5 & M6 in pull-out = 86 kg
Double drywall: M5 & M6 vertical = 268 kg
Single drywall: M8 & M10 in pull-out = 51 kg
Single drywall: M8 & M10 vertical = 174 kg
Double drywall: M8 & M10 in pull-out = 100 kg
Double drywall: M8 & M10 vertical = 290 kg

How often do you mount something that weighs more than 174kg? Today's TV or hat shelf is not close to that.
Perhaps the sink in the bathroom, where there's a risk that someone might sit on it.
But where you know fixed installations will be, you place a board behind the drywall, inside the wall.

Njaaaaa...

How often do you hang something on the wall with M8 or M10?

 

[Yrrol]

How often do you hang something on the wall with M8 or M10?

Sure, but let's say M5 & M6 vertically = 132 kg.. That's almost the weight of two people..
I do admit that if you know people will be jumping on things, like the sink. Then put a board behind it.

And of course, it becomes annoying if you've placed something slightly wrong. But on the other hand, if you move a coat rack half a cm, the screw will likely slip into the previous hole in the wood panel as well.
*brings back horrible memories when drilling in concrete/brick/lightweight models and the drill suddenly veers off*

 

[geschwint]

I would definitely put up OSB, partly for the sound dampening but mainly because if you need to screw something in, and you will, you can just use wood screws. For an upstairs in my place with three rooms and about 12 meters of wall per room, it becomes 36 meters + hallway. Under 40 sheets at 109kr each at Byggmax, ~4000kr is not a dealbreaker in this context. I just think the craftsman overestimated when it comes to the work. 20-25k could give you 2 men for maybe 4 days... It should *not* take that much extra time to put up OSB with two men.

 

[geschwint]

Sure, but say M5 & M6 vertically = 132 kg.. That's almost the weight of two people..
I do admit, if you know people will be jumping on things, like the sink. Then put a board behind it.

And of course, it will be annoying if you set something a little wrong. On the other hand, if you want to move a coat rack half a cm, the screw will probably slip off against the previous hole in the wood as well.
*awakens horrible memories of drilling in concrete/brick/light models and the drill suddenly veering off*

But you can intentionally screw it at an angle to grip fresh material, doesn't really work in plaster. And since osb sits ~13 mm behind, you'll get a proper shift to the side to fresh board.