teach me about insulation and noise.

[Travis Conner]

So my 30x50 metal building I bought to use as a shop has no insulation on the walls or ceiling. I was told that this can make the whole shop act like a megaphone, so I guess that means the noise will just bounce off the walls and go out the shop doors. Standing 40ft or so out in the street I want to say the shop noise is maybe a bit louder than the sound of a normal conversation. I'd prefer the neighbors across the street not hear anything. The neighbor has a garage somewhat in between the house and my shop, so hopefully that drounds out most of the noise. If i insulated the walls and ceiling will this make a big difference in the noise exiting the bay doors? What other ways can I use insulation to encapsulate noise? You can only put so many tools inside sound shields. Noise ordinances say noise from the property should stay below 55db which imo is ridiculous in a rural area. Eventually I'm going to probably put a central hvac system in, then I can just keep the doors shut, but one thing at a time here.

[roger wiegand]

While the experts will tell you that insulation makes relatively little difference, and most of the sound is transmitted through the solid framing and such, requiring sophisticated double wall construction to isolate and seal walls, my experience is somewhat different. I used open cell spray foam to insulate my 1910 barn when I converted it into my shop. The difference was instantly apparent. On walking in after the installers left my immediate impression was that the place was like a tomb. Eerily silent, with none of the outside noise entering.

With doors closed you can barely tell that the DC and table saw are running inside. I have no idea where that 55 db number comes from; just the leaves rustling and bugs in our yard are louder than that, not to mention noise from the street 400 feet away. Standing in my driveway on a still day with no human-generated noise evident I typically get readings in the low 60's. We might get to 55 on a still night after a heavy snow.

[Jim Becker]

Insulation for environmental purposes will also help with noise control. But it's also important to have "soft surfaces", too, particularly for mid to higher frequencies so they are absorbed rather than reflected. The biggest mistake around noise control in a shop is having all hard surfaces. Go to any restaurant with big high ceilings and limited soft surfaces and try to hear yourself think...

BEST thing I did in my shop (aside from the minisplit after insulation) was putting in the acoustic ceiling. "Yuge" difference... It's not necessary to do a whole ceiling, but ensuring there are sound absorbing elements will go a long way to making sound transmission inside (and outside) of the shop more palatable.

[Bobby Robbinett]

The best way to prevent noise from exiting is to use double layer drywall with green gue and sound isolation clips with roxul or similar insulation in the walls. I would focus more on insulation for HVAC efficiency rather than sound issues. In that regard, spray foam is the absolute best thing you can do to easily heat and cool your shop. Here where I live it runs $1.45 per square foot installed for spray foam. At least do your ceiling in spray foam as with a shop of that size it won’t be much and your cost benefit ratio is very good. For the walls you could do roxul safe and sound or really any good product like that. It would be good to build vented, insulated enclosures for your compressor and dust collector. Put your machines on rubber anti vibration pads.

[Bill Dufour]

AFAIK Rockwool insulation is the only one that is rated to be left exposed with no drywall. Exposed will collect dust and be impossible to clean but it will soak up noise. In theaters they hang sound absorbing blankets and panels from the ceiling to kill echos.
Bil lD

[Ron Selzer]

Farm shops report that spray foam insulation, about 2" with fiberglass batts. Then cover with perforated steel panels really knock down the sound in larger shops.
Good luck
Ron