Adding sound insulation between floors?? Foam??

   / Adding sound insulation between floors?? Foam?? #1  

Nilesw

Bronze Member
Joined
Feb 15, 2004
Messages
57
I am remodeling a 17 yr old house and we are redoing the carpet n the master bedroom which happens to be over the living room. The original plan was to tear up the subfloor and roll in insulation but that is just not possible as the subfloor is plywood put down with 3 inch nails every about 4 inches. I talked to the pro foam insulation guys and the job is not big enough for them to come out. Does anyone have any ideas how I can add some sound proofing?? I thought about buying a bunch of cans of that "great stuff" expanding foam insulation and drilling half inch holes and filling with as much as I can get to go in but I don't know if that stuff is safe around wires?? Anyone got ant help in this area. Any advice is greatly appreciated!!

Niles
 
   / Adding sound insulation between floors?? Foam?? #2  
Niles,
I don't know if it is safe with wiring or not, but places like Grainger has a canister like freon comes in with 10-20 lbs in it for big jobs. I don't remember the exact size, but it beats using several dozen spray cans.
 
   / Adding sound insulation between floors?? Foam?? #3  
Niles,

Got a similiar situation at my house in that the computer room is over the living room and any chair movement is loud downstairs. Thought about drilling two 3 inch holes between each floor joist and blowing in insulation, then patching the holes with sheetmetal before recovering the floor. I would like to replace carpet with solid flooring so the chair rolls better but don't know if that insulation will blow very well sideways in a floor rather than vertically in a wall. The other risk (I think) is that light weight soundproofing will only attenuate high frequency and it takes some serious weight to absorb the lows. So all that trouble and it may be a disappointment. Your foam may be too light as well but at least it would seal up any openings that sound may be coming thru.

A friend used that foam to insulate his walls when he built the house. They had to apply the foam before drywalling and then saw off the excess flush with the face of the wall studs. The obvious technique seemed to be to squirt it in the cavity after drywalling but the foam expansion over that big of an area bulges and pops the drywall. Imagine how your LR ceiling would look if that's true.

John
 
   / Adding sound insulation between floors?? Foam?? #4  
There should be no need for sound deadening if you are installing a new carpet. The carpet will kill the noise. I have a second story on my house with hardwood flooring upstairs. The noise is not that bad. I did not use anything in between the floors for sound deadening. I did however use 2"x10"s for the floor joists upstairs. I think this may have helped to keep the noise down a bit.
 
   / Adding sound insulation between floors?? Foam?? #5  
Nilesw . . . be very careful with the foam! There are several types of "expansion" foam that are used for insulation, some of the foams are LOW expansion and some are HIGH expansion.

If you are shooting a high volume of foam into a confined space you must use the LOW expansion foams. If you use a HIGH expansion foam it can literally push the ceiling out below you and pop the floor boards in the upper room.

Most of the cans sold at the retail stores are HIGH expansion foam and are very safe for using in SMALL spaces to seal around pipes, fill in small holes and cracks, etc. I would suggest you take a look at the before mentioned suggestion and check out Grainger, they may have exactly what you need.
 
   / Adding sound insulation between floors?? Foam?? #6  
You can go to the local DIY lumber store, Home Depot, Lowes...etc. And rent a cellulose blower. Some places even offer free use of the blower with enough material purchased.
 
   / Adding sound insulation between floors?? Foam?? #7  
Niles,

It's easy to think that the empty cavity between your floor joists causes a "drum" effect, and that is where the sound is coming from. But you also need to remember that sound travels through the joist themselves. My father built a soundproof room in our house years ago, and the walls were double thick, with offset studs, insulated in between. And I've since read articles about soundproofing rooms. (I'm getting ready to build a house this fall) They all say you offset the studs in a double wall, insulate, and then have two lays of drywall. And I've seen write-ups on how to make ceilings sound-proof, and it always involves hanging the ceiling on a grid of material running perpindicular to the joists, which limits the sound travel through the joists. I know you don't have this option, but I just wanted to let you know that insulating may not help as much as you may think. Carpet will help a lot, especially if you invest in a nice heavy weight pad, and insulating may help some, but you're not going to get rid of all the noise.

And be careful with any kind of foam. You'd be amazed at how strong it is when expanding.

Josh
 
   / Adding sound insulation between floors?? Foam?? #8  
This may sound like an inane way to insulate between floors but it worked for the person who asked me to figure out a solution. About ten years ago I had a customer with a two story rental property who wanted to soundproof part of the upper floor from the lower level...noisy tenants, which led to disputes.

When the first floor was vacated I just cut out a foot wide section of ceiling drywall at a right angle to the joists the entire width of each room. From there it was easy to slide in batt insulation between the joists and all that was left to do was attach replacement drywall to the joists, then patch, sand and paint. As the rooms were empty and being repainted it wasn't much additional mess. However, I doubt if this method would be practical if you are not planning to redo your living room.... /forums/images/graemlins/smile.gif

If using fiberglass between floors, use the type with no paper vapor barrier...and check carefully for any concealed wiring before and while making the drywall cuts. As my customer wanted to add ceiling fans in some rooms, this method also made is easy to add wiring and boxes during the sound proofing procedure.

I would NOT use foam for this type of work, most types are highly flammable and it would be quite expensive compared to using batt or blown insulation.

Just my opinion.

Bill
 
   / Adding sound insulation between floors?? Foam?? #9  
For soundproofing, you don't want to foam. You want to blow cellulose between studs and floor joist. Save yourself a lot of time, money and disappointment. Foaming will not do the job.
 
 
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