I am currently working on converting my detached garage to an Accessory Dwelling Unit (ADU). The detached garage is close to a relatively busy street, so there is a decent amount of noise generated from cars, people walking by, etc. I am trying to figure out the best way to reduce noise. The simplest solution seems to be to just double up on Sheetrock, but I am concerned that may not be enough. Maybe there is a certain type of insulation or sound absorbing panels that are best for this. I did some Google and Reddit research, but the feedback is all over the place. I am curious if anyone has some first hand experience on what works best.

Any feedback would be greatly appreciated.

If your able to insulate still, use Rockwool insulation.

They make a specific sheeteock that helps reduce noise. There's also some physical barriers like mass loaded vinyl you can hang before the sheet rock as well, or between two sheets of sheeteock.

And, don't put a windows in that wall if you can avoid it.

If you already have a window in a as "noise-adjacent" wall, these might help.

https://indowwindows.com/solutions/window-noise-reduction?utm_keyword=soundproofing%20windows&device=m&utm_source=google&utm_medium=cpc&utm_campaign=Sound_Proofing_Core&utm_adgroup=Proof&gad_source=1

You are removing the garage door and framing up the opening, right? Otherwise none of this will matter.

Thanks for the response. This ADU is in Dallas, so I have to deal with Green Building standards. As a result, I am required to use insulation that is R-13 or greater. I noticed that Rockwool does not have an R-value on their products. In fact, their website says their interior insulation products do not require an R-value, so they do not brand their interior insulation with this information. No idea how that affects my Green Building requirements, but I will try to get some answers from the city.

I will look into the noise reducing sheetrock and mass loaded vinyl. It may be that combination of all of these things is the way to go. I already put a window on the noisy wall, but it appears another poster may have a solution for that.

Thanks for the suggestion. I didn't even know these existed. There is already one window on that wall, so this could be a good solution for that.

Yes, I have already removed the garage door and framed in a new wall. I have also already removed the existing sheetrock. I figured now was the time to make a plan for reducing noise before I hang new sheetrock.

Rockwool is one of the better performing insulation options out there.

Iirc, rockwool batts have an R value of about 3.5 per inch.

This product works good

Have used to isolate media room noise as well to quiet bedrooms

https://www.lowes.com/pd/QuietRock-Common-1-2-in-x-4-ft-x-8-ft-Actual-0-5-in-x-4-ft-x-8-ft-500-Drywall-Panel/3069747