Sound barrier between bath/bedroom

[beds]

I have 2 bathrooms side by each and I'm converting one bathroom to be part of a bedroom. This is on a main floor. Both rooms share a dirt-floor crawlspace. The shower in the remaining bath is on the common wall. I am concerned about the noise from the bath affecting the bedroom (these are separate rental units).

Things I am considering to lessen the noise are:
2x6 framing
"sound" insulation batts
2 sheets of drywall

I'm not going to have any electrical boxes on this wall in either room.

Anything else I should consider?

 

[DaveNay]

I have 2 bathrooms side by each and I'm converting one bathroom to be part of a bedroom. This is on a main floor. Both rooms share a dirt-floor crawlspace. The shower in the remaining bath is on the common wall. I am concerned about the noise from the bath affecting the bedroom (these are separate rental units).

Things I am considering to lessen the noise are:
2x6 framing
"sound" insulation batts
2 sheets of drywall

I'm not going to have any electrical boxes on this wall in either room.

Anything else I should consider?

If you can spare the slight reduction in floor space, the best sound barrier is to put in a second 2x4 wall (or 2x6) that is spaced about 1/2" from the existing wall, and also make sure the studs are spaced in between the existing ones. Then add fiberglass batts into each bay of both walls.

Other options include:

• Cast iron soil and vent pipe - much quieter than PVC
• Double layers of drywall (combined with the double wall above is great)
• ???

 

[bczoom]

Instead of 2x6 framing consider doing a double stud wall. Put a 2x6 for the sill and top plate and install 2x4's for studs on each side offset evenly between each other. (E.g. if studs are 24" on-center on one wall, the studs for the other wall will be offset 12" from the first wall but still 24" OC). This will create a baffle for sound.

Not sure how much room you have but if there's any way you can put a gap between the 2 sheets of drywall that'll help as well. Using 1" furring strips or 2x4's laid flat are more than adequate.

 

[bczoom]

Dave posted the same time I did but I like the way he thinks!

 

[beds]

If you can spare the slight reduction in floor space, the best sound barrier is to put in a second 2x4 wall (or 2x6) that is spaced about 1/2" from the existing wall, and also make sure the studs are spaced in between the existing ones. Then add fiberglass batts into each bay of both walls.

That sounds like a gret idea! Then I could keep the existing 2x4 wall in tact. I was thinking of taking it down and putting the 2x6 up because it was shabbily constructed with 3/8" wallboard. But a new 2x4 wall would be less work.

I was thinking of insulating under the floor of the bathroom, but not sure if that would be enough or if I should do the bedroom as well. There is ducting in the crawlspace, so it is "warm" in winter.

 

[DaveNay]

Instead of 2x6 framing consider doing a double stud wall. Put a 2x6 for the sill and top plate and install 2x4's for studs on each side offset evenly between each other. (E.g. if studs are 24" on-center on one wall, the studs for the other wall will be offset 12" from the first wall but still 24" OC). This will create a baffle for sound.

Not sure how much room you have but if there's any way you can put a gap between the 2 sheets of drywall that'll help as well. Using 1" furring strips or 2x4's laid flat are more than adequate.

If you need to completely replace the wall, Brians method is better (uses less floor space).

 

[Junkman]

Instead of 2x6 framing consider doing a double stud wall. Put a 2x6 for the sill and top plate and install 2x4's for studs on each side offset evenly between each other. (E.g. if studs are 24" on-center on one wall, the studs for the other wall will be offset 12" from the first wall but still 24" OC). This will create a baffle for sound.

Not sure how much room you have but if there's any way you can put a gap between the 2 sheets of drywall that'll help as well. Using 1" furring strips or 2x4's laid flat are more than adequate.

I did exactly as Brian suggested when building my home between the two bedroom walls, and it didn't work very well. I have since learned that it is the bottom floor plate that needs to also be separated. It was since suggested that if you want the wall to be totally soundproof, then build it out of 2 x 4 turned 1/4 turn and cut the bottom plate 2 x 4 down to 1 1/2" in width. Then cover the inside wall with homosote. Build a second wall just like the first, for strength, but leave a 1/2" space between them. Put homosote on the room side of both walls first and then sheetrock. This will make for a quiet room. If your building code doesn't allow for turning the 2 x 4 on edge, then build 2 standard 2 x 4 walls using the above method. What is more valuable... noise abatement or loosing a few inches of floor space???

 

[DaveNay]

I did exactly as Brian suggested when building my home between the two bedroom walls, and it didn't work very well.

Hmmm....yeah, like I said in the first place.

Don't listen to that Brian guy.....d'oh!

 

[beds]

I did exactly as Brian suggested when building my home between the two bedroom walls, and it didn't work very well. I have since learned that it is the bottom floor plate that needs to also be separated. It was since suggested that if you want the wall to be totally soundproof, then build it out of 2 x 4 turned 1/4 turn and cut the bottom plate 2 x 4 down to 1 1/2" in width. Then cover the inside wall with homosote. Build a second wall just like the first, for strength, but leave a 1/2" space between them. Put homosote on the room side of both walls first and then sheetrock. This will make for a quiet room. If your building code doesn't allow for turning the 2 x 4 on edge, then build 2 standard 2 x 4 walls using the above method. What is more valuable... noise abatement or loosing a few inches of floor space???

Junk, did you insulate as well as homasote? I had never heard of that homasote before and just had a look at it.

I am definitely on board for building the 2nd wall. I will keep the existing wall there if I can, as it has perfectly good tile on it in the bathroom. I can lose the 6". Keep a gap between the bottom and top plates. Drywall both sides of the new wall and put homasote on the living-side of the wall.

 

[Junkman]

The homosote is a paper product that absorbers sound. Use it on the interior and exterior before sheetrock. Fiberglass insulation doesn't have much effect, and it can't hurt, but it might help somewhat. Problem is that you can't get much in between the walls. If you could put 10" between the walls, then it will work for sound, but 6" doesn't do as well. Homosote is cheap, so use more. If you build the wall on the floor then put it on both sides. It is easier to do it right the first time than to take it down a second time. Make sure that the walls don't touch each other.

 

[Grooming Snow]

Did you ever try the spray type of Insulation ? That works great with a 2x6 wall studs . Spray it on and sound proof

 

[johnday]

Just stumbled on this thread. Junks advice is sound, that's the way I'd do it too, with a slight addition. Use some cellulose insulation between the two walls also. I just started using cellulose a few years back, and it's the best sound deadener as far as insulation goes. And no, it doesn't settle like the old stuff did. Now adays it's sprayed in, and fortified with a latex binder, that keeps it from settling. I'm using it upnorth for the whole house, and interior walls surrounding the bathroom.
Another thing I've seen people do is insulate the floors in their crawlspace. DON'T do it. With your forced air ducts running in there, they are actually keeping the floors warm.
Have you considered a wall in the crawlspace where the living units are divided? That might help with a little noise transmission too?

 

[beds]

Just stumbled on this thread. Junks advice is sound, that's the way I'd do it too, with a slight addition. Use some cellulose insulation between the two walls also. I just started using cellulose a few years back, and it's the best sound deadener as far as insulation goes. And no, it doesn't settle like the old stuff did. Now adays it's sprayed in, and fortified with a latex binder, that keeps it from settling. I'm using it upnorth for the whole house, and interior walls surrounding the bathroom.
Another thing I've seen people do is insulate the floors in their crawlspace. DON'T do it. With your forced air ducts running in there, they are actually keeping the floors warm.
Have you considered a wall in the crawlspace where the living units are divided? That might help with a little noise transmission too?

I wasn't going to insulate the floors in the crawlspace, as I've probably read the same stuff. Building a wal down there is a good idea, although I dread every time I have to cram my body into that little space. I'm not sure about the cellulose - 'm unfamiliar with it and it sounds expensive.

Another issue I'm donna have is the ceiling above this room is also kinda thin - 1 sheet of drywall, 1" T&G pine, carpeting and what feels like 1/64" of underpad. I was thinking of builiding another false wall for the ceiling, but then was thinking about what others were saying about building it on a separate sill plate, and got all confused. I guess, ideally, you would build a box inside of the current room and only attach it to the walls where needed. This project is getting pretty big in scope. But don't they all....

 

[johnday]

Man; wish I was there, this could be knocked out fairly quickly. This wall should not be a bearing wall, so it doesn't have to be built like the existing one. Picture a wall built the normal way, with the studs and top and bottom plate both 3.5" in depth. Now, when most of us build stud walls, all the stuff is laying on the floor. Lay out your studs like you normally would, except turn them 90 degrees, so the wide side, 3 1/2", is lying flat on the floor, and the top and bottom plates are still on their narrow edge. Then just nail away. When you stand the wall up next to the existing one, make sure the top and bottom plates are about 1/2" away from the wall, and the wide dimension of the studs, is on the "room" side of the plates. You should windup with a cavity between the two walls 2 1/2" to 4" deep.When you attach this second wall, do not nail it to the first, you'd just be defeating your purpose. You will have to nail thru the floor sheathing, and hoefully your cieling joists are running 90 degrees to your top plate. Still no big deal though. Since it sounds like you've got a second floor that you want to isolate also, just bust a hole thru the cieling and nail some bridging in to catch the top plate. I'm not real sure about what you're asking about the second floor. Is this to be divided also?

I think I might know what you're asking, but give me a little more to go on, and maybe I can help further, that is if I have at all.

Just where in Ontario are you?

PS. The cellulose does cost a tad more than 'glass, but you will have zero voids. 'glass in my opiion is a thing of the past.

 

[beds]

Thanks, John, I think what you're describing is what I want. I want to sound-dampen the ceiling in this room as it is noisy on the 2nd floor which is another apartment. I'm going to be running new duct work in the ceiling in that room which has 10' ceilings. The joists do run perpendicular to the wall I'll be putting up.

Could you do cellulose yourself or do you have to get someone in to do it? I should look into it.

And I'm in London.

 

[bczoom]

Thanks, John, I think what you're describing is what I want. I want to sound-dampen the ceiling in this room as it is noisy on the 2nd floor which is another apartment. I'm going to be running new duct work in the ceiling in that room which has 10' ceilings.

How about installing an acoustical ceiling (aka. drop ceiling)? At 10', you should have plenty of space.

Here is one I'm working on (although not completed in the pics). I've since installed can lights and finished it.

 

[johnday]

Could you do cellulose yourself or do you have to get someone in to do it? I should look into it.

And I'm in London.

I've never tried to do the modern day cellulose with the binder in it. I believe it takes a special spraying machine. What it does is mix water and the latex binder with the cellulose. Call some insulators and see what they'd charge. Some of tham are still setup for 'glass only, and they'll try to tout their own virtues though, but I would imagine someone in your area has modernized.
You've got the ideal situation with that 10' cieling. You could do as Brian has done, but if you want the benefit of the cellulose, I think you'd have to go with drywall. I could wrong there, call those insulators and see what they think. I've never seen it on top of anything but drywall. If you lower that cieling to 8', you could blow it full, and have close to 2' insulation. That oughta' quiet things a lot.
London, eh. Windsor is only 35 miles from me. Right now, I started truckdriver school today. But if you don't get it done, let me know. The only problem I have is getting back into the US. The Customs people on our side of the river are something "real special"!

 

[beds]

Call some insulators and see what they'd charge.

I'll do that! Certainly no harm and if I don't have to put another batt of fiberglass insulation up in the 100 degree heat, I won't be bothered.

London, eh. Windsor is only 35 miles from me. Right now, I started truckdriver school today. But if you don't get it done, let me know. The only problem I have is getting back into the US. The Customs people on our side of the river are something "real special"!

If you're getting a steady route, I hope it's not across the border! It's awful to see the trucks queued up for literally hours in Sarnia and Windsor. Thanks for the offer and info, John!

 

[beds]

How about installing an acoustical ceiling (aka. drop ceiling)? At 10', you should have plenty of space.

Here is one I'm working on (although not completed in the pics). I've since installed can lights and finished it.

That looks great, Brian. It would be nice to access the duct work, too. Do you find it deadens the sound?

 

[bczoom]

That looks great, Brian. It would be nice to access the duct work, too. Do you find it deadens the sound?

Thanks.

I did use those specifically so I could get to wiring, plumbing and HVAC in the future.

Yes. They do deaden the sound, BUT you need to get the right tile. Some of the cheaper tiles (or the tiles made years ago) are worthless for sound.

There are 2 things that you'll want to watch when purchasing the tile. The mfgr's brochures should give you the numbers.

NRC - Noise Reduction Coefficient

This measures how much sound is absorbed when sound hits the tile. You can get tile that will absorb as much as 80% although most are around 50-60%.
​

CAC - Ceiling Attenuation Class

This measures how much the tile can stop sound from passing through it.
Good tiles will give you a rating in the 40 - 44 range. Other tiles will rate in the 30's.​

I used some basic Armstrong tile (model is "Impression" or product # 1135).
Although I no longer have the boxes or brochures (where the NRC and CAC were printed) but I believe the NRC was 60 and the CAC was in the mid-30's.

 

[johnday]

Thanks for the offer and info, John!

Nary a problem, just keep us posted, and fire away anymore questions you may have!