Add sound deadening to existing ceiling

[nh_handyman]

I've got a lake house that was built a few years ago. The primary bedroom is on the first floor with two bedrooms and a bath above it.

I asked for but I suspect, did not get sound insulation installed between the two floors.

The second floor is hardwood - and that isn't being ripped up to add insulation.

So - what can I do to add some sound deadening to the ceiling?

I've considered a few things

1. cut holes in every joist bay and pump cellious insulation in - patch holes - re-paint
2. rip out most of the ceiling and install dense batt insulation - install new ceiling
3. Do step 2, but also add second set of strapping and use 5/8 sheetrock

Thoughts?

 

[bud16415]

I belong to a home theater forum and many people go to great lengths to soundproof home theaters to both keep theater sound from getting out and house sounds from getting in.



The way it is commonly done is by using decoupling clips between the framing and the first layer of drywall. There is then a second layer of drywall put up with a product called green glue that comes in caulking gun tubes. It is a sound insulating product that keeps the layers acoustically separated.



If a couple inches of ceiling height isn’t an issue the ceiling could be strapped down and then the theater ceiling design added below that. I would think that would involve the least amount of mess in the end.



I’m not an expert on the subject and have never done one as in my home theater there are just the two of us and when we run it we are normally in there together. if one of us is sleeping above and the other is using the room we just play the sound softly or switch to headphones and forgo the subwoofers.



AVS forums has a forum on dedicated home theater DIY builds and if you do a little searching there you will find dozens of threads with photos showing how folks do soundproofing.

 

[Eddie_T]

If one is careful hole patching in a ceiling or wall is quite easy. I glue a thin strip or strips on the unfinished side to support the plug that I cut out. When the glue has dried I glue the plug into the hole with glue on edges and back. Mark the plug before cutting so orientation will be maintained.

 

[bud16415]

Most of the sound is transferred thru the ceiling joists not the air space. Adding blown in insulation upward is not an easy thing to do and get a good fill.



When a wall is built between say two bedrooms they often do a double offset stud wall to break up the sound transfer. It is also a nice way to do outside walls with a 2x6 plate and 2x4 studs offset so you don’t get a similar heat transfer.

 

[Eddie_T]

I successfully blocked sound in my home with insulation. With speaker and cajon experience I know that cavities do resonate and amplify. My in-wall insulation deadens sound of toilet flush from bathrooms sharing wall with LR.

 

[bud16415]

I shouldn’t have implied that in wall insulation doesn’t stop sound if that is how it was taken. It will deaden sound. My belief is that without decoupling it will always be limited.

 

[Snoonyb]

We use a system, not identical to, but similar, in the RON HOWARD screening room, WALLS, for USC; isoTRAX™ Soundproofing Isolation System | Soundproof Cow

The room was so sound deadened that they had to add a base noise for the sound system to operate correctly.

 

[PJB12]

The trick is to minimize the solid connections between floor above and ceiling below. Also, it's important to not have a "drum" cavity to resonate sound.

Maybe...
Instead of using furring strips in your Step 3, NH_Handyman, Hat Channel would help transfer less sound because it's resilient & has an air gap. (It looks similar to the layers in the isoTRAX thatn Snoonyb mentioned.) This is inexpensive and is used in commercial often for sound isolation. It comes in 1/2", 3/4", 1" and 1-1/4" height.

Run it perpendicular to the existing joists. Use a zig-zag of adhesive that will remain pliable forever both on the channel flange and on the face for the new drywall. Perhaps subfloor adhesive or construction adhesive is appropriate?

Use coarse thread construction screws to attach the hat channel to the joists.
Use fine thread drywall screws to attach the drywall ceiling to the hat channels.

You can leave the existing drywall up and screw the hat channel through it & into the joists. Or you can take down the old drywall.

If you leave the old drywall up, use a hole saw to put holes in the existing drywall to insulate.
One Idea: Put an extension tube on water based minimally expanding type of spray foam and fill each joist cavity.

Or, put the new drywall up and spray just the gap between the old & new ceilings, patching the holes in the new ceiling as you mud & finish the drywall.

Or: Shoot in loose fill insulation. (Less expensive than foam, I'd imagine)

Three Cautions:
1) Use the Minimally Expanding foam. It's often called "Window & Door" foam.
2) Use non-flammable insulation. The yellow foam expels flammable gas while curing. I have had some latex Window ones that don't
3) If there are any recessed lights in the ceiling, they MUST be rated to be insulation covered. If they are not, don't put the foam.

Enjoy The Silence!
Paul

 

[nh_handyman]

Thank you for all the replies. I'll start looking at these options and weigh the costs (and ask the ultimate boss of course!)