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Insulation between floors


kramttocs's Avatar
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07-13-15, 08:04 AM   #1  
Insulation between floors

Due to a very uneven floor and adding some light fixtures I am replacing the subfloor of one of the upstairs bedroom in my cape code. We are going to be replacing the carpet with laminate. While I am in there I will be adding foam blocking under the exterior walls but was wondering about adding some insulation to help out with tv noise and what not.
I am not going the whole soundproofing gambit so it's just a matter of insulation or not.
So-

1. Would it help with tv noise and such? I know it wouldn't help with noise traveling through the solids.
2. What thickness?
3. Does facing matter? Difficult to find unfaced r13 or r19 it seems.

The upstairs is two bedrooms and a bathroom. This bedroom will be the only one I am thinking about doing this in.

If I put the insulation in I have to think that it will make the downstairs warmer and the upstairs floor colder in the winter by slowing down the heat rising. Would this be insignificant?

 
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07-13-15, 04:19 PM   #2  
Insulation will do very little on the noise issue. I'm not saying not to do it but don't expect a miracle. However, it may change the heat. Do you have steam, hot water or forced air heating? Is your goal to keep the heat, on the first floor?

 
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07-13-15, 06:00 PM   #3  
We've got forced air (heat pump). A unit for downstairs and a unit for upstairs. During the winter we generally run a pellet stove downstairs.
I completely understand that insulation isn't going to work miracles, I just figure now is the time to do it if it's the right choice.

 
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07-13-15, 06:10 PM   #4  
The foam blocking (air block) below the kneewalls is the most important, insulation wise. Then the floor of that side attic space needs full r-50 insulation with a baffle to allow soffit air to flow in. That air path needs to be continued to the high vent area in some manner.

As for adding insulation in the floor, adding a foot or so behind that foam block is good, but the rest, as far as insulation is concerned will only separate the two floors. As for sound, Roxul makes a "safe and sound" material, similar to their insulation, very dense. If you installed Roxul full depth in those cavities it would provide some sound benefits.

Bud

 
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07-13-15, 06:25 PM   #5  
With the floor joists being 2x10s and the Roxul coming in 3.5 inches I am afraid I can't justify the cost of filling the 300+ sqft room with it.

I had settled on unfaced R-19 with the cost being around $200. Would you say it's not worth it?

 
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07-14-15, 05:19 AM   #6  
Roxul does come in 6" thickness, but you are correct, it would be more expensive. Cellulose would be the least expensive.

Just thinking out loud. Since your objective is sound reduction maybe some sound reducing techniques. Another layer of drywall, flat or at a shallow angle would absorb some and reflect some. But, as others have stated, at best you will still have the sound passing through those 2x10's

I can't say how effective the r-19 will be.

Bud

 
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