O/T Installing insulation

I'm installing insulation on my girl friends house and i'm wondering what is the best insulation to use in the walls. According to the insulation they recomend R13 or 19 for walls. Her brothers are very noisy, so the more sound proofing the better. I was thinking R30 if you squeese it down will it make for better sound proofing. We are more after soundproofing the walls than actually insulating them. I am also thinking about doubling up the sheetrock between the rooms to help. I think it will take a lot of yelling to go through 4 pieces of sheetrock and insulated walls. The walls are constructed out of 2x4's.

not sure about using the r-30 insulation but doubling the sheetrock does help.

Compacting insulation smaller than the space it is intended for reduces the effectiveness of both sound and insulating properties. The right R value and doubling the sheetrock is probably your best bet.

Compressing the insulation reduces its usefulness. If you have a 2x4 wall, then your insulation should only be 4" deep. If you use foam board insulation, you can get a higher R value, but it costs a lot more.

The R-13 recommendation is for a 2x4 exterior wall, not an interior. I believe you need a 2x6 wall to get the R-19 value with batten insulation.

If you are concerned about noise, make sure you use 1/2" sheetrock as a minimum. Consider 5/8" sheetrock rather than doubling it.

if a new wall use foam under bottom plate and on top of top plate, (noise side) glue 1/2 foam board to the studs, cover with 5/8 drywall glued to foam, only need to do on one side. Glue all trim on
NO PENETRATING FASTNERS, NO ELECTRIC OUTLETS, NO OPENINGS OR PENETRATIONS
other side (her side) 1/2 drywall, can use fastners.
FOAM MUST BE UNPENETRATED AND COMPLETLY COVER THE NOISE SIDE OF THE WALL. USE SPRAY FOAM TO SEAL ALL CRACKS TOP AND BOTTOM

next best is 2 walls with seperation between all studs, plates etc

3rd best is a 2x6 plate top and bottom with staggered 2x4 studs. weave insulation thru the studs
good luck

Ron

Oops I meant r15 instead of 19. is there a big difference between 13 and 15

Check with a commercial drywall distributor or contractor. There are such things as sound attenuation strips that ca be attached to the studs, and then the drywall is attached to the strip. Used extensively in apartment building where you don't want sound traveling to adjacent appartments. Do Some research and save yourself some money.

I work for a commercial drywall contractor. We use 3-1/2" unfaced batt insulation. 5/8" drywall is a little better than 1/2". You can also use the old celotex type sheathing under the drywall.

The metal strips are called resilient channel. The face that the drywall is screwed to is offset from the leg that's attached 24" o.c. horizontally to the framing. It usually just goes on one side of the wall. As mentioned, double walls or staggered studs also works. It's used often between apartments.

Larry in Michigan

For sound attenuation, I have often used Roxul- mineral wool, it's greenish in color and I believe actually has 3 desirable propeties. 1.) Fire Rated and is listed in the UL Fire Resistance Directory, for use in firestop assemblies to pack out the annular space in through floor and through wall penetrations, like pipe, conduit etc. 2.) R value for insulation 3.) Acoustical/Sound Attenuation.

I think this material is more common in commercial or multi unit residential buildings, any good drywall supply house should be able to get it.

One thing with sound attenuation, is fasteners, I believe that is where most sound is transferred, especially with metal studs, maybe not so much with wood framing, even when joint compound covers the fastener head, less fasteners, less sound transfer, some research on that may help too.

With some research, you should be able to pinpoint a wall type that suits your needs to dampen sound better than what you have, typically on a set of building design drawings, there are details of all the specific wall types for the building, and they vary depending on fire ratings, sound attenuation/acoustical and room usage.

See the link below, another similar material would be thermafiber, either or, check out the website, Roxul is a quality product, with some good specifications for sound absorption.
ROXUL

Maybe a good old fashion a** kicking would help more than extra insulation. Might quieten those rowdy boys down some. Just a thought.

Larry, do you know what the spray on vapor barrier stuff is? Does it work? Supposed to be some type of spray on vapor barrier and then you can use unfaced insulation. Thanks.

(quoted from post at 04:18:10 11/21/09) Maybe a good old fashion a** kicking would help more than extra insulation. Might quieten those rowdy boys down some. Just a thought.

Click to expand...

I agree, just the loudest one has ticks, and extreme ADD. He gets very loud and throws weird fits.

My suggestion is at midnight get up and quietly move.
Walt

Use the r-13 in 2x4 walls then get the sound-proof type sheetrock. Putting thicker you need 2x6. The insulated sheetrock seems to be great according to those who install it.

Hi Tim,

The best bang for the buck is styrofoam insulation, R7 per inch. 2" Rigid foam 4ft x 8ft was $20 and 1" was $10 at HD/Lowes last month.

So 4" would be R-28. Styrofoam is 90% air.

Remember that a dead air space is the best insulator, so be sure to seal all the outside/inside air leaks before installing any type of insulation.

Butyl caulk is the best caulking of any type.

T_Bone

Couple comments...
In general, squishing down insulation doesn"t help. it usually hurts. Insulation works because of all the small airspaces - when you compress them, they go away.

The comment above about sealing the gaps is a good one - this is critical in knocking down the airborn sound.

We"ve used a product called Quietrock in high end commercial condo"s and had great success. It"s a little expensive ($80 a sheet during the last building boom) but not that bad for small installations. Basically 2 layers of drywall laminated together with an acoustic decoupler. We used one of their better systems and when finished ran a circular saw in one condo about 5" from the wall and heard nothing in the other condo.
here"s their site - has some good info on different levels of installations:
www.quietsolutions.com

Any way you go - remember sound travels in waves both by air and through vibration. So make sure you try to isolate both.

Good luck

Tony

I was alway under the impression that ROXUL wasn"t available on the States. Is it hard to get/special order or do they stock it in the lumber yards?