JosephThomas

Sound insulation

Recommended Posts

What is the best way to get sound insulation in a garage shop?  I'm in California, so temperate weather, most garages here have zero insulation in the walls or up in the rafters.

The walls on this garage have stucco walls, 2 layers of paper, then 2x4 studs.  The roof is asphalt shingles, paper again, some 2x underlayment, then the rafters (no dropped ceiling or anything like that).   I do not need/want to do any kind of insulation for the sake of heating/cooling, simply trying to add enough sound dampening that I could work later at night without disturbing the neighbors. No shared walls, but the neighbor's house is <10 feet away.    Is the best route to just add batts between the studs, and would I see any difference if I upgraded to a superior product like roxul's stone wool?  Should I be adding sheet goods or drywall over the top and air sealing as well as possible?

Share this post


Link to post
Share on other sites

Fibreglass insulation won't do much. Either get a dense pack cellulose done or insulate with Roxul comfortbatt.  I would add quietrock to be extra safe. That should be suffice to keep neighbours from wanting to stab you.

Share this post


Link to post
Share on other sites

Also, there is a door to the exterior facing the neighbor.  I don't need to use the door too often, is there anything I can do short of building an actual wall over it, that would help insulate sound? 

Share this post


Link to post
Share on other sites

make sure that there aren't any gaps around it. Have you ever been outside your shop and had someone else run a board through a planer or anything before? It might be a good idea to get a baseline .

  • Like 1

Share this post


Link to post
Share on other sites
3 minutes ago, Chestnut said:

make sure that there aren't any gaps around it. Have you ever been outside your shop and had someone else run a board through a planer or anything before? It might be a good idea to get a baseline .

Yes, it was basically like being inside the garage, lol. The old garage door had 1 inch gaps all around, and was mostly made of 3/8" plywood, so that was the biggest failure point. Single pane glass on the window, etc.  Now that some of those variables are changing, I'm trying to see what else I can do. Ideally I'd like to be able to work up until midnight during the week...I don't necessarily need to use the planer at that hour, but using the DC along with TS or BS or at least whacking something with chisels and a mallet without disturbing anyone would improve my productivity and happiness a lot.  

Is air sealing more valuable than adding insulation? ie. Assuming a fixed budget should I spend first on some good soundboard/drywall/sheetgood and seal all the joints really well, instead of adding insulation between the studs?

Share this post


Link to post
Share on other sites

Dense materials are what absorbs sound.  Not sure if you have drywall on the inside of the walls?  If the studs are open then adding insulation is fairly inexpensive and better to do it while it's open than to find out you need something more after you've already drywalled.  If it has drywall already I wouldn't worry about the insulation and just add a second layer of drywall over the top.  I think they make some special adhesive for this for sound deadening purposes.   On the door if you want to go crazy you can add a layer of MDF.

Share this post


Link to post
Share on other sites

You'd lose a little space but, if you put up some soundboard, then a lathing strip, and then drywall over that you'll get quite a bit of sound dampening.  That's what I did when I had the recording studio and it worked quite well.

  • Like 2

Share this post


Link to post
Share on other sites
2 minutes ago, krtwood said:

Dense materials are what absorbs sound.  Not sure if you have drywall on the inside of the walls?  If the studs are open then adding insulation is fairly inexpensive and better to do it while it's open than to find out you need something more after you've already drywalled.  If it has drywall already I wouldn't worry about the insulation and just add a second layer of drywall over the top.  I think they make some special adhesive for this for sound deadening purposes.   On the door if you want to go crazy you can add a layer of MDF.

No drywall on that wall that faces the neighbor.

Share this post


Link to post
Share on other sites

Any thoughts on "sound blankets" or thick moving blankets? They seem like a decent option to hang over the door so that it's easily removable, but has anyone tried this?

Share this post


Link to post
Share on other sites
7 minutes ago, JosephThomas said:

Any thoughts on "sound blankets" or thick moving blankets? They seem like a decent option to hang over the door so that it's easily removable, but has anyone tried this?

This can be a fairly cheap first step.  Do a test run with the planer with you in the driveway, and then hang blankets on the garage door.  I'd guess a half dozen or so would do it, and you'd get a bit of feedback on whether it will work for you or not.   If it doesn't you end up with some decent utility blankets.   But yes, blankets like that can be used for sound absorption in the right scenario. 

Share this post


Link to post
Share on other sites

Anything that absorbs vibration will help, but not a lot. I have played with anechoic panels that would make you swear you went deaf in the one ear you carried it near. The problem is that it takes a fair amount of density of loosely packed fiber it seems. Those panels are expensive also. Blankets would need to be quite heavy to have a big effect. You could be as far ahead by putting a fence panel a few feet outside the door. Reflecting directional sounds can sometimes work. 

If you try blankets, hang them over a sheet of two inch foam. 

Share this post


Link to post
Share on other sites

Obviously sound is a wave stop it from getting out is step 1, step 2 is stopping it from transferring through. If you have huge gaps you could spend a ton of time on the wall but the door is going to let sound out.

  • Like 1

Share this post


Link to post
Share on other sites
1 minute ago, Chestnut said:

Obviously sound is a wave stop it from getting out is step 1, step 2 is stopping it from transferring through. If you have huge gaps you could spend a ton of time on the wall but the door is going to let sound out.

I agree. Just not sure what to do about it for the door.  When I asked "is air sealing more important" I am referring to the walls/rafters, not the door.

Share this post


Link to post
Share on other sites

JT, so all the walls are just studs at this point?  If so, I would use the same products Shane mentioned.  Once done with that I would look at making acoustic panels and hang on the walls and ceiling.  Homosote supposedly deadens sound, but personally the stuff seems like garbage.  More expensive option would be to find out what they use in recording studios.

Share this post


Link to post
Share on other sites

I would not waste your time or money on the blanket angle.  As others have suggested you need mass to absorb sound.  The reason I say pass is I was in a condo that faced a busy road and my son's room would get some loud car and truck noises in his room (the background din was not an issue).  I bought specialty sound blankets used for temporary sound recording studios to cover the windows.  Because they were set sizes I was able to double the blanket material over the window.  The blankets were very heavy ~5-10x the weight of a moving blanket. Bottom line, there was an improvement, but not significant and at $80 for 2 blankets you have better/more options.

Hope this helps.  Let us know what you do.

Carl

Share this post


Link to post
Share on other sites
11 minutes ago, JosephThomas said:

I agree. Just not sure what to do about it for the door.  When I asked "is air sealing more important" I am referring to the walls/rafters, not the door.

Ahh there not so much if you sheetrock or w/e that will act as air sealing for sound at least.

Share this post


Link to post
Share on other sites
12 minutes ago, JosephThomas said:

I agree. Just not sure what to do about it for the door.  When I asked "is air sealing more important" I am referring to the walls/rafters, not the door.

Hang the blanket here..  Soundboard, lathing strip, and drywall the rest.  Out less than 100 bucks to do the whole wall..  Don't make me come down there and show you ;)

 

Share this post


Link to post
Share on other sites

Sound is vibration.  Vibration moves things.  Moving things makes sound.  So if your machine is vibrating that gets transmitted everywhere and vibrates everything it is exposed to.  Studs, sheathing, the air, it all vibrates, which in turn makes sound.  Sound hitting a wall, with a single layer of sheathing (and you can count everything layered on a single side of a wall) will pretty much ignore the wall as the wall itself will vibrate at the same frequency.  In some cases you may find the harmonic frequency of the surface and it will actually amplify the sound.  Studios isolate sound with a system called MAM (mass, air, mass) and the method is essentially a heavy wall, a space (usually insulated) and a heavy wall not connected to the other heavy wall in any way (because sound will travel through the connection), including the floor and ceiling.  A box within a box.

That is the extreme, mass is your friend (unless you hit one of the harmonics).  The sound you don't care about is the ones no one can hear.  Below 20 Hz and above 20k Hz.  More mass generally means lower harmonic frequency.  Walls in studios are actually tuned so those harmonic frequencies are below our threshold of hearing.

That is some of the science behind it (it gets more complicated when you start looking into lengths of sound waves and reflected sounds).  Make your walls air tight, make them heavy, sheath in rafters if they are open, use Roxul if you can.  It will all help.  An insulated wall with sheathing on both sides would count as a single layer in studio terms, but that will increase the mass and dampen the frequencies so it helps.  Plus, sheathed walls give you places to hang things.  Doors ought to be as air tight and as heavy for the same reasons (big studios use air locks with a door on either side, sometimes 400 lbs in weight or more).  Single pain glass will let a lot of sound escape.  A second pane mounted in a groove in wood with rubber or silicone keeping the glass from contacting the frame and added to your window (like a storm window) will help somewhat.

Things like packing blankets and soft walls will help with some of the high frequencies, but more importantly, they help stop sound from bouncing around.  Sound can bounce off several surfaces at the same time and meet in places inside, and outside the room and amplify themselves with standing waves meeting.

Hope that helps a bit.  When you start to understand the problem, it becomes easier to deal with it.

  • Thanks 1

Share this post


Link to post
Share on other sites

1/2" thick Homasote sheets are $25 at Menards. It's made from recycled newspaper, deadens sound and is treated (w borax I think) to resist termites and fire. I have used it for many years to make bulletin boards. 

Share this post


Link to post
Share on other sites
24 minutes ago, wdwerker said:

1/2" thick Homasote sheets are $25 at Menards. It's made from recycled newspaper, deadens sound and is treated (w borax I think) to resist termites and fire. I have used it for many years to make bulletin boards. 

I paneled bedroom walls and ceiling on a job with Homasote ripped and beveled to random widths of 3”-8” like old wood vertical paneling. It truly does make for quiet spaces. I had forgotten about it. 

Share this post


Link to post
Share on other sites

If you rip that stuff on a tablesaw wear a dust mask ! I tasted old newspapers for a few days !  Learn from my mistakes or you are doomed to repeat them ! But Homasote is one of those time tested products that's still around. Several small local building supply places carry it around here. I've always got a sheet or so in the shop for bulletin boards. Burlap or cork make great coverings for it. A roll of cork can be quite pricey but it is the classic covering for a bulletin board.

I used Homasote to line computer printer cabinets, those old school printers were LOUD !

Share this post


Link to post
Share on other sites
1 hour ago, Chestnut said:

Ahh there not so much if you sheetrock or w/e that will act as air sealing for sound at least.

Yeah got it.

1 hour ago, TIODS said:

Hang the blanket here..  Soundboard, lathing strip, and drywall the rest.  Out less than 100 bucks to do the whole wall..  Don't make me come down there and show you ;)

 

I hear you guys...but I loathe drywall. The process of hanging it, mudding, sanding is all fine.  But I hate it because you can't hang anything from it directly, and it makes a huge mess if you have to ever get behind it.  Can I get similar results with ply or OSB (I would caulk or tape the joints)...or is there something magical about drywall that makes it more efficient for sound deadening?

It is just the one wall I'm concerned with, since it faces my neighbor,  the other 2 are attached to my house (and are drywalled already) and the 4th wall is 90% covered by the garage door (another issue entirely).

Share this post


Link to post
Share on other sites

You can't hang stuff on the Homasote directly but you could hang OSB over it. 

I agree w the hatred of finishing Sheetrock ! That's a job for painters, not craftsmen !

Share this post


Link to post
Share on other sites

JT if you wanted to you could use roxul on the existing stud wall, then build another wall, and offsetting the studs.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now