Adding sound dampening insulation to existing interior wall?

[wild_turkey 3159]

Is it possible to do this? I've heard of injectable foam insulation that gets injected through small holes, which looks like I would need to find a local company that offers this. Does it actually help reduce sound transmission?

Alternatively, could I cut a 3-4" hole near the ceiling between each stud and manually add insulation through the hole? Then patch the holes?

Looking for options that don't involve tearing out the drywall and replacing it entirely.

[royiv 9302]

Installing a torture room?

[mdmost 43001]

Sex dungeon?

[baboso 6054]

Egg cartons stapled to the walls, bro. 

[horn4life 3760]

I have a common wall with our Master bedroom that of course did not have insulation in it as it was an interior wall.  I looked into it and the foam is a possibility but a more expensive option. The problem with putting in anything after the fact is that you have electrical wiring going horizontally to all the plugs, that blown in or non-expanding foam can hand on and not completely fill.  The new foams may be light enough to flow past the horizontal wiring and full the space, but a few years ago that was a question.

Here is my hillbilly engineering solution.  But you are going to have to do some sheet rock repair no matter what you do.  My solution was to make fairly large holes about a foot off the ceiling.  make sure the hoes are between thee studs. (Ask me how I know this... ;-). )And use the blown in insulation to fill the void in the wall.  The larger holes with come clearance from the ceiling allow you to sort of see into the void and gives you the ability to put some of the blow in insulation into the void and use something to help push it around the wiring to fill the bottom of the wall.  You can tell if the insulation made it all the way down by knocking on the sheet rock where you are trying to fill the void.  You can hear the difference with a duller thud when the void has insulation in it.  The other reason for the larger hole is that you can then cut some normal roll insulation to size and tuck it up to fill the void above the blown in insulation.  I put the insulation by hand rather than blow it in for the first part, the used the blower to top off once I had the bottom filled.

This method will work and it is a lot cheaper.  The one WARNING I would give is that if you are going to go the spray in foam route, add any electrical or future cable drops into the wall before the foam goes in.  As once the foam goes in good luck doing anything in the wall without tearing the wall out.

The other method... Buy some Outlet extenders for any plugs on the wall and add a layer of noise absorbing sheet rock.  There was also some sort of sound deadening material that could go between a new layer of sheet rock that worked pretty well. But I researched those options a few years ago.

Good luck!

[Elvis 3371]

What noise are you trying to contain or keep out?  Home theater?  Street noise?

[HornOnTheBayou 8921]

3 hours ago, horn4life said:

Here is my hillbilly engineering solution.  But you are going to have to do some sheet rock repair no matter what you do.  My solution was to make fairly large holes about a foot off the ceiling.  make sure the hoes are between thee studs. (Ask me how I know this... ;-). )And use the blown in insulation to fill the void in the wall.  The larger holes with come clearance from the ceiling allow you to sort of see into the void and gives you the ability to put some of the blow in insulation into the void and use something to help push it around the wiring to fill the bottom of the wall.  You can tell if the insulation made it all the way down by knocking on the sheet rock where you are trying to fill the void. 

Um, are we still talking about insulation?

Edited August 24, 2022 by HornOnTheBayou

[wild_turkey 3159]

What noise are you trying to contain or keep out?  Home theater?  Street noise?

Master bedroom shares a wall with what will become an infant’s bedroom. Noise transmission through the wall has always been subpar but it never mattered before.

[wild_turkey 3159]

My solution was to make fairly large holes about a foot off the ceiling.  make sure the hoes are between thee studs. (Ask me how I know this... ;-). )And use the blown in insulation to fill the void in the wall. 

That’s the type of solution I had in mind. On the surface, it seems like it should work.

Would you say it helped reduce sound transmission in your case?

[Jkwellborn 6697]

If you have crown mounding, I’ve seen videos where people take that off and cut holes behind it to blow insulation in.

[UT_OB1 2220]

14 hours ago, horn4life said:

I have a common wall with our Master bedroom that of course did not have insulation in it as it was an interior wall.  I looked into it and the foam is a possibility but a more expensive option. The problem with putting in anything after the fact is that you have electrical wiring going horizontally to all the plugs, that blown in or non-expanding foam can hand on and not completely fill.  The new foams may be light enough to flow past the horizontal wiring and full the space, but a few years ago that was a question.

Here is my hillbilly engineering solution.  But you are going to have to do some sheet rock repair no matter what you do.  My solution was to make fairly large holes about a foot off the ceiling.  make sure the hoes are between thee studs. (Ask me how I know this... ;-). )And use the blown in insulation to fill the void in the wall.  The larger holes with come clearance from the ceiling allow you to sort of see into the void and gives you the ability to put some of the blow in insulation into the void and use something to help push it around the wiring to fill the bottom of the wall.  You can tell if the insulation made it all the way down by knocking on the sheet rock where you are trying to fill the void.  You can hear the difference with a duller thud when the void has insulation in it.  The other reason for the larger hole is that you can then cut some normal roll insulation to size and tuck it up to fill the void above the blown in insulation.  I put the insulation by hand rather than blow it in for the first part, the used the blower to top off once I had the bottom filled.

This method will work and it is a lot cheaper.  The one WARNING I would give is that if you are going to go the spray in foam route, add any electrical or future cable drops into the wall before the foam goes in.  As once the foam goes in good luck doing anything in the wall without tearing the wall out.

The other method... Buy some Outlet extenders for any plugs on the wall and add a layer of noise absorbing sheet rock.  There was also some sort of sound deadening material that could go between a new layer of sheet rock that worked pretty well. But I researched those options a few years ago.

Good luck!

This will work and you can do this with the actual blower instead of trying to push it in by hand.  HD will rent the blower to you for free after you purchase X amount of bags (10?).  

[PhillyD 1257]

I've seen a solution where a second layer of drywall was added over the top of the existing layer on one of the walls separating the rooms.  A very small layer of air (maintained by the drywall epoxy or whatever it is called) was between the two to further help prevent sound transmission.  You need to insulate any outlets on that wall as they are the weak spots where sound comes through.

Im not a sound engineer or a contractor, but I stayed at a holiday inn Express once.  I've also seen this technique in ceilings between floors to help stop noises between the two floors.  It made a significant difference and was a lot easier than trying to go inside and insulate.

[Homercles 10205]

May want to switch out the door for solid core or something more substantial as well

[NotActuallyALonghorn 4976]

Seems like adding a second layer of drywall would be almost as much work as just removing the existing drywall and adding proper insulation.

[Quagmire 2147]

Have you tried telling the baby to STFU?

[millhouse 2604]

Obviously,  the only viable solution is to buy a new house.

[Upgrayedd 5810]

Don’t know how blown in or foam helps to get around horizontal draft stops in between the studs.

Remove drywall one side. Add resilient / RC channels.  Make sure electric outlets are not back to back.  Insulate.  Solid core door.

Make the kid do it to earn keep.

[horn4life 3760]

9 hours ago, UT_OB1 said:

This will work and you can do this with the actual blower instead of trying to push it in by hand.  HD will rent the blower to you for free after you purchase X amount of bags (10?).  

Oh use the blower for sure.  But if you start off blowing in the insulation you will have it catch on the wiring and not fill the bottom of the void in the wall.  So put the first stuff in by hand, and use a stick or something to push the loose insulation below the wiring then... fill her up.  The on/off on the machine can be a little tricky unless you want to blow a lot of insulation into the house while jumping to the next whole.  Nothing a helper can't fix. Good luck!

[royiv 9302]

Vigorously shake the baby for a minute or two. It will quiet right down.

[Homercles 10205]

18 hours ago, wild_turkey said:

Master bedroom shares a wall with what will become an infant’s bedroom. Noise transmission through the wall has always been subpar but it never mattered before.

Not sure what you’re worried about.  Not gonna get laid again anytime soon 

[Jkwellborn 6697]

We have hard foam and solid doors in our office at work. Under no circumstances do I recommend either of these things for sound deadening.

An insulated door and bat insulation is gonna be the best bet.

[TeeDubya 3362]

Ideally, eliminating studs touching both wallboard (staggering them) is best.  Solid materials transmit sound pretty well.

If you're not into rebuilding the whole wall, loose fill cellulose is probably your best bet.  another layer of drywall is decent too.

https://homeguides.sfgate.com/increase-soundproofing-existing-wall-40553.html

[Sam Lin 3556]

If you want to really nerd out on this, USG is a huge manufacturer of construction materials, and they have an excellent guide that shows construction methods for acoustic mitigation. It obviously focuses on their products, but the structural diagrams and principles apply to anything and are very clear and easy to understand. Diagrams start on PDF page 15.

 

http://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/acoustical-assemblies-en-SA200.pdf

[Elvis 3371]

https://www.avsforum.com/threads/soundproofing-master-thread.1509173/

[horn4life 3760]

Seemed like when I was doing research some rubber between layers of sheet rock was about as good as blowing in the stuff.  But seems like the material was expensive.  But I looked and found some 1/4 inch think rubber matting.  Not cheap but a lot cleaner and quicker, IF (do your research) the sound deadening of a rubber barrier might work better.  I was thinking get some outlet extenders, enough rubber matting for to cover the wall, and rubber tape for seams, and then 3/8 sheetrock over that.  just find the studs and make them on the floor and ceiling with tape and re-rock the wall with the 3/8.  I think there are some outlet extenders that are nearly right on for that additional thickness.  

Or better yet just make an entire wall of that puzzle looking kids mats on the wall?  Might look cool and could be used as a giant bulletin board as time goes on? Them removed in later years where eaves dropping becomes more important! 😉

 

[wild_turkey 3159]

Appreciate all the suggestions.

I’m not looking to completely soundproof the room, just somewhat reduce the sound transmission through the wall. You can hear normal conversation through it pretty easily as it is. Not really an issue now, but it may be frustrating when there’s a baby in there and we’re trying to sleep.

Also, we probably have 2-3 more years in this house, so I’m leaning towards an easier fix like adding insulation over a more complicated fix like replacing the drywall.