Insulation for soundproofing / cold floors...


Old 02-26-02, 07:47 PM
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Insulation for soundproofing / cold floors...

I'm building a house and my builder allowed me to go in to put in some insulation for soundproofing purposes in some of the interior walls. I also put insulation between the 1st and 2nd floor (2 storey house). I've heard this can cause the 2nd floors floor to be colder then normal.

Has anyone had experience with this. I have engineering floor joist in the floor which are about 1 foot deep. I put in R12 batts. The batts are hanging at the bottom of the 1 foot floor joist and there is about 8 inches of air space above the batts. I've heard that this cold floor can happen when there is no air circulation in those joists. I'm hoping that because the batts are hanging down that I won't have this problem, but I was wondering what oppinions I can get here. Thanks.
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Old 03-04-02, 11:26 AM
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Hi Renes
Sorry I have no answers for you, only questions. We are also going through a builder and they asked us if we wanted soundproffing. We opted to do the Master BDRM since it is over the great room. She said it would be $150 or you could do it your self. Now I am not sure what I am getting myself into here. At what stage did you lay the insulation. Was the ceiling on, and you just laid the batts between the Joists, or did you have to support it with polly from underneth?
Good Luck
Old 03-06-02, 08:41 AM
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Sorry I'm late. I haven't checked back here in a few days. Here are the stages of the house leading upto my insulation installation:

1. Framing
2. Plumbing rough in
3. Heating rough in
4. Electrical rough in

At this point the city inspectors came in to check all rough ins and check the structure of the framing. Once everything was passed I was given about a 1-2 day buffer where I was allowed to come in and install any speaker wire and other low voltage wiring I wanted (cable, telephone/network). After I did my wiring I installed my batts. It was right around the same time the insulator had come in. I watched him install the exterior wall batts to get an idea how to handle the batts properly.

I used R12 since it is the highest R value I could find that fit in 2x4 walls (I did alot of the bedroom walls too). The floor joist on my second floor were 24" on center. My builder said it wasn't 19" on center because it was a lower load floor. Anyway that made it easy to buy the batts since 23" and 15" are the two sizes available. My floor joists an engineered floor. This simply means "I" beams. This made hanging the batts really easy. If you have 2x10's then I think the friction fit batts might loosen before the drywallers come in to install the ceiling.

You can't install vapor barrier to hold up the batts. In Canada anyway there are code issues with installing vapor barrier on interior walls and non-attic ceilings. You should use the red colored "duct tape". This is the tape used to tape rips or seams in the vapor barrier. It cost me $11 a role but it is supper sticky. I bought the tape thinking I would need it to hold the batts but the "I" beams held better then I thought they would. With the tape though you could just run a length of tape 90 degrees to the beams. Then the batts could simply sit on the tape. The tape sticks really well to wood too. You only need the batts to sit there until the drywallers come in. When my drywallers came in last week they told me they come across interior batts all the time.

I haven't gotten an answer on my original question yet, but the insulation company strongly suggested that I didn't completely stuff the floor with insulation. Buy thinner batts that will allow for an air gap between the upper floor plywood and the batt. In other words if you have smaller batts, hang them down to the bottom of the joist.

I expect the insulation will eliminate higher frequency noise like most voices, part of music. But the lower frequency noise like walking and subwoofers won't be dampened that much if at all. You need sound bar for that. But that is another story.
Old 03-13-02, 07:24 AM
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Talking flooring insulation

Hello to all,

I have pretty much the same setup. I have a 2 story, walk up attic finished (still in progress). My floor joists are LVLI's (laminated I beams) 16"O.C. at 11 7/8" deep, 3/4" strapping running 90 deg to the joists. I have put r13 in the interior walls, r19 (2x6) on the outside and I am planning on putting r13 non faced in the ceiling for sound control. although with 3 boys that will be tough anyways. you can allready hear the difference with the walls done. I was concerned also about a "cold" floor. I am taking r19 faced, cutting it into 12" peices, and putting them at the ridgeboard on each end of the joist to stop the cold from penitrating the ridgeboard and creating a cold floor. hope this helps some.
Old 03-27-02, 01:36 AM
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Some ideas:

Owens Corning makes a sound attenuation batt called Quiet Zone. It's not rated for R-value but is specifically designed to impede sound wave transmission through walls. I'm installing this in my house now and don't have any feedback as far as cold floors go. Generally speaking, when insulating between floors and walls for sound proofing, you do want an air space. Ex: drywall---insulation---air space---drywall or drywall-----insulation---airspace----plywood flooring. Sometimes airspace in walls is not possible since the insulation takes up all the space between the 2x4 walls. The more changes a sound wave has to make- (i.e, the more differnet materials it travels through) will cause more sound attenuation to take place. If sound is a real issue, I'd also suggest using acoustic caulking to seal areas where sound can escape (i.e., around drywall, etc.). I've also heard success stories using homasote ( on the studs before the drywall -or- double layers of drywall. However there are many effective solutions for sound proofing.
Old 03-27-02, 08:58 AM
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I built a house 18 months ago and insulated between the 1st and second floor with craft faced R19. The craft paper provided an excellent friction fit and a staple tab in a few unique hanging situations. I removed the paper near heat ducts and can lights. Make sure you leave mfg recommended space around can lights. Some can lights are thermal protected and allow insulation to be laid over, others require open space clearance. Extra insulation was added on the sides and top of drain pipes. (water makes alot of noise running through PVC) We have not experienced cold floors at all. We have experienced muted noise from teenagers playing music and talking on the phone!

On inside walls, we insulated with unfaced R13 on the first floor where sound control was desired. (make sure you don't put insulation in cold air return cavities). Friction fit was fine for vertical installation. Solid core doors were used on rooms where extra quiet was desired. The perimeter of every room was caulked where the floor meets the bottom plate of the wall. Outside walls (floors, corners and around windows) were caulked by the insulation team to stop air leakage. Inside walls at the floor plate to floor were done by me for sound control. It was alot of caulk but buying in case qty didn't cost much. Someday I'll get around to caulking around the electrical outlets...

I talked to a few experts that have alot of insulation experience who said not to waste money on the plastic covered insulation, just wear gloves and glasses. In addition, the extra cost for insulation marketed as "sound insulation" is not worth the money. If money is no object, using double drywall, double thick 2 x 4 walls with offsetting studs, drywall channel and other solutions may be worth looking into.

Hope this helps.
Old 04-05-02, 11:29 PM
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STC is sound transmission class

The stc rating of a standard 1/2 inch drywall 2x4 wall is around 15

by using R-13 ( note that using higher R values lowers STC ratings) resilient J channel 5/8 type X drywall on either side you can achieve an STC of around 50.

I would not worry about cold floor syndrome .. if your HVAC is balanced and working properly I dont see any problems

If you are looking to soundproof only certain rooms... heres some tips

1 - make sure outlets switches etc that are between two rooms dont share the same stud cavity
2 - be sure to caulk around the drywall after its installed on floor around outlets etc
3 - use resilent metal j channel on ONE side only ..not necessary on both sides
4- offset vents in common airspace cavities
5 use 5/8 X type fire drywall on both sides

Also once you achieve anything over 30 or so.. the door to the room becomes the weak point.. but solid core doors can be had with STC up around 50-60

Hope this helps---Josh
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