Searching for best products to insulate as well as deaden sound.

[Bill Jobe]

Would foamboard with foil facing on both sides against the exterior wall plus some sound deadening bat insulation on the inside provide the best of both insulation value and maximum sound deadening in my 12x20 shop with 2x4 studs?
Would I benefit from a layer of foil faced foamboard on both sides of the batting?
Moisture will be a problem, but from what I have been able to glean from reading the foil faced foamboard would handle that.
Also, there seems to be some difference of opinion amongst members as to whether or not to cut the foamboard to fit snuggly or cut it narrow and fill the gaps with spray foam.
Seems to me the ideal method would be to cut it to fit snuggly but apply minimum expending foam to fill cracks and gaps prior to fitting the foamboard.
Opinions?

[Bill Dufour]

Climate? with extrra words to make minimum

[Bill Jobe]

Hi Bill,
Upper midwest. Iowa-Illinois Quad Cities. Moline, Davenport, Rock Island area.
Temps range between as high as 105F to -30F.
I am also asking what R value would be recomended.
2" foamboard is, I think, r-11 and the sound deadening batting insulation should bring the total R up to around 15, plus the addition of foil for both decreased heat loss as well as sound deadening.

[andy bessette]

What you're suggesting is OK for thermal insulation, but will do virtually nothing for sound deadening. Research acoustical isolation techniques.

[Bill Jobe]

Much of what I've read on the subject lists aluminum foil as one of the best sound barriers availablw.

[Mike Kreinhop]

Mass is your friend when trying to reduce sound transmission. I build facilities and rooms that require at least 50dB of attenuation, and from my experience, aluminum foil is transparent to sound. I use the foil in some applications, but for a different reason. The absolute minimum I start with for a gypsum wall construction is two layers of 5/8-inch GWB on each side of the studs and densely packed insulation between the studs. Depending on the requirements, each surface of the wall will have its own studs with the extra space between the studs will be densely packed with insulation.

If I can't find the metric equivalent of the GWB, then I add more layers on each side until I have the desired thickness. It is very important that no seams overlap and the edges of the GWB are sealed with acoustic sealant where they touch the walls, floors, and ceiling of the main structure. All wiring is surface mounted to the completed wall, as access holes in the GWB create opportunities for sound to leak.

Take Andy's advice, and research acoustical isolation techniques for wall and door construction.

[phil harold]

1" foam will help with thermal bridging
then cover with 5/8 sheetrock
screw resilient channel on and then screw another layer of 5/8 sheetrock into the channel

Resilient channel is a thin metal channel that is intelligently designed to substantially improve the sound insulation of drywall, sheetrock, plasterboard walls and ceilings. The channel effectively isolates drywall from the framing studwork, which results in the weakening of sound waves substantially.

[Bill Dufour]

Foil will do nothing in your application for thermal effects. Foil must face free air to reflect heat. Shoved against siding does nothing, covered by insulation on the inside does nothing.
Bill D.

[Bill Dufour]

Roxul makes a product for sound reduction but they do not rate it for R-value. Their r rated material is heavier then fiberglass and I would suppose more sound reducing then fiberglass.
Bill D

[Bill Jobe]

Thanks everyone for your input.
A 2x4 cavity seems so little to work with to achieve both goals.

[Frank Pratt]

Foam board with foil will do next to nothing for sound blocking. Neither the foil nor the foam are much good a it. How about strapping the studs with 2x2 & isolation clips. Better than the clips would be to build a staggered stud wall in front of the existing wall. Then stuff the cavity with Roxul Safe'n'Sound. Then use a couple of layers of 5/8 fire rated gypsum board with Green Glue between them.

Effective sound blocking is a 3 way approach; isolation, absorption & mass.

Not sure who gave you the story about the foil, maybe someone that sells foil faced board?

[Frank Pratt]

1" foam will help with thermal bridging
then cover with 5/8 sheetrock
screw resilient channel on and then screw another layer of 5/8 sheetrock into the channel

Don't do it quite this way. Resilient channel should not have gypsum board or foam board behind it. The channel should be installed directly over the insulation. The problem with having 2 rigid surfaces is that the sound radiating from 1 layer is easily picked up by the other, something akin to 2 antennae facing each other. Testing has actually shown the doing it this way negates the benefits of the resilient channel.

[phil harold]

Don't do it quite this way. Resilient channel should not have gypsum board or foam board behind it. The channel should be installed directly over the insulation. The problem with having 2 rigid surfaces is that the sound radiating from 1 layer is easily picked up by the other, something akin to 2 antennae facing each other. Testing has actually shown the doing it this way negates the benefits of the resilient channel.

hmmm
that makes sense
thanks for the tip!

[Bill Jobe]

What he said

[Jim Andrew]

There used to be a product lumberyards sold called "sound board". Looked like celotex but had no black coating. Would think a layer of 3/4" celotex would make an excellent sound deadening material. Along with filling your voids with insulation. My nephew bought blue denim insulation to insulate his basement ceiling, said it is the best sound deadener. He has 5 kids.