9

Assuming the construction was done properly, would 3/4" OSB (oriented strand board, it's like a particle board but better) a better soundproofing material than 5/8" drywall?

This OSB has an R-factor of 0.90, which is really good. 1/2" drywall of course is abysmal at 0.45, but actually 5/8 drywall isn't much better with an R-factor of 0.5625.

Compare this to common brick. Brick has an R-factor of 0.80, so the OSB has even a brick wall beat.

1" plywood actually has an R-factor of 1.25, just a side note.

Soundproofing has several elements:

  • mass (weight, density)
  • airtight
  • absorption (e.g. foam [good] vs thin steel [bad])
  • damping (e.g. green glue)
  • resonance (e.g. foam [good] vs metal [bad])

Mass is non-negotiable. If you put two sheets of 1/16" plastic together with green glue and make it airtight, it still isn't going to do much. And because plastic has little absorption, the sound may well pass right through. So that's an example of a poor design.

OSB seems to kill it with mass. Not only is it nearly the same price as drywall, but it has nearly double the R-factor of 5/8 drywall. In fact, it's similar to having two sheets of 5/8 drywall (without green glue).

That's not the only benefit of OSB. If I wanted to put it on a hinge or screw something in, OSB is a lot greater material since it can hold a screw, and not crumble under its own weight. It's possible with drywall but you also need to build a full frame for it which not only increases the cost and resonance (both bad) but is a ton more work.

The downside of OSB is finishing it, but for some applications it doesn't matter. The best way is to seal it with resin, or sand and paint before install. If you don't need to finish it, there isn't much downside to OSB as far as I can see.

Also, cutting to shape is easier and less messy. There is some sawdust but drywall has drywall dust which is way more messy for install.

The only thing I don't know about is resonance of OSB. However, being strands of wood held together with glue, I'm guessing it should be at least comparable to drywall if not better - but this is just a guess so don't take my word for it.

You could even put two layers of OSB with green glue, and anectodal evidence says it is about the same benefit - except that the 3/4 OSB will have double the mass of the 5/8 drywall, so possibly far greater sound reduction.

So, can 3/4 OSB be a better bet for soundproofing than 5/8 drywall, for the same installation?

  • 2
    Where do you plan on using it? There are far better materials available for soundproofing, but not all of them are suitable for all applications. If you're talking about a house or other building, you may need to use drywall because of its fire-resistant properties. – mrog Jan 23 at 18:08
  • Already answered below, but finishing seems way harder with OSB. As you are talking about doing two layers, you could always do drywall over OSB and get all the finish advantages and structural advantages. – UnhandledExcepSean Jan 23 at 18:09
  • I am creating a large window plug for my apartment. I am basically covering the window airtight with materials. Drywall was first thought, double with gg also considered, OSB now also an option. plywood probably not good due to higher resonance, but OSB is not plywood and is strands held together with glue, all good for breaking up sound waves. – diy user Jan 23 at 18:21
  • @UnhandledExcepSean yes I considered that and if I do two layers I might do that or even plywood which is smoother, though not as good as OSB, may be good paired with it. Or, just two layers 5/8 drywall. However I do want to know if I only do one layer which will be better, the 5/8 drywall or the OSB – diy user Jan 23 at 18:23
  • 2
    @user2966384 Have you considered expanding foam contained within a bag to create a plug? – UnhandledExcepSean Jan 23 at 18:42
8

3/4” OSB board is better than 5/8” gypsum board.

Sound control is measured in STC ratings (sound transmission coefficient).

Here’s a website that tests various materials: https://www.ecopacificinsulators.com/uploads/4/7/1/6/4716609/sound_transmission_stc_rating.pdf

Gypsum board is not as good as OSB board. 1/2” OSB board equals 5/8” gypsum board.

As you can see, 3/4” OSB board is not listed, but OSB board increases by +1 for each 1/8” thickness. Therefore, you could surmise that 3/4” OSB board would be +6, and 5/8” gypsum board is +4 and fire rated gypsum board is only +5.

4

For the best noise insulation, try layering materials with different acoustical properties. For example, you could sandwich some foam board between two layers of OSB. As the sound reaches each of the material transitions (air to OSB, OSB to foam, foam to OSB, and OSB to air), a great deal of it will be reflected back. Additionally, the foam will absorb some of the sound. This is the strategy used by some commercial products that consist of foam-filled rigid panels.

1

According to this website,

As for soundproofing- it (OSB) very similar mass to drywall and hence, will give similar results.

So, I would expect the thicker OSB to insulate sound better.

0

I don't have science to back this up, but there's more to it than mass. Internal structure is also a large factor. Because gypsum is soft, it may have more ability to resonate internally and diffuse sound energy, whereas plywood or OSB may have more tendency to propagate the sound through drumming.

I'd take the drywall over the wood.

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