# Insulating Existing Interior Walls



## MAD King (Dec 14, 2010)

Hello,

I am trying to figure out how much blown in insulation I need per sq ft for an existing interior wall.

Thank you


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## joecaption (Nov 30, 2011)

Going to need more info and your location add to your profile.
Go to Quick links to edit.
No one here can see your house.
How deep, how tall and wide ECT.
http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table


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## MAD King (Dec 14, 2010)

Hello,

didn't know that there is a R-Value for existing interior walls too.
What information would be needed?
I thought there would be an approx. amount of blown-in insulation per sqft for empty interior walls.


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## joecaption (Nov 30, 2011)

And how would anyone here know just how thick these walls are or what type blown in your going to use unless you share the info?


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## MAD King (Dec 14, 2010)

Sorry, but I am new to this and if I bother you with my inexperience please take my apology.

I think these are regular 4" walls with a reular height of 8'.
Type of blown-in insulation woul dbe cellulose.


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## asinsulation (Apr 11, 2011)

for soundproofing or separating thermal zones?


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## MAD King (Dec 14, 2010)

A little bit of both. But that wasn't my question.

Thank you


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## asinsulation (Apr 11, 2011)

I am well aware that wasn't your question, but your application is going to change depending on what your desired final result is buddy


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## asinsulation (Apr 11, 2011)

if thermal is the idea, you need to densepack. if sound is the idea, you want the cellulose a little loose, like a pillow. 

Anyway, give me the width of the walls, and I will tell you how many bags you need to densepack. already have the height and depth, so just the width.


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## asinsulation (Apr 11, 2011)

or this is even easier. as long as your measurements are accurate above, you will need a little more then 3 and half bags for every 10 feet, assuming you are using 25 lb bags.


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## MAD King (Dec 14, 2010)

Oh wow, thank you very much. That is very accurate.


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## Nailbags (Feb 1, 2012)

I would use Dense pack insulation if your going for sound and thermal zoning. just know there is settling with lose fill so you might want to check out doing a dense pack less settling.


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## asinsulation (Apr 11, 2011)

The number I gave him is for densepacking, minus a little for framing members and the fact that if you haven't densepacked before, your not going to get it as tight as it should be. but he should find a happy median with this.

If it is truly a densepack, it will carry the vibrations and have no effect on noise reduction, and its not like we are trying to control a 30 or 40 degree temp difference as you would be on exterior walls. also, much less opportunity for moisture intrusion on the interior walls


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## MAD King (Dec 14, 2010)

Thank you. I am trying to find where to buy dense pack, but google gives me only installation instructions.


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## Windows on Wash (Aug 30, 2011)

Be aware that dense packing is not a great DIY job. Not only are the blowers that you get as rentals equip to dense pack, it is an acquired skill that takes a good, long time to get good at.

Dense packing is usually a job for the pros.


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## Gary in WA (Mar 11, 2009)

MAD King, I see looking at your other posts that you are from Germany? Welcome to the forums! "Dense-packing" cellulose is an installation procedure when insulating; http://www.karg.com/pdf/Insulaton_density/Dense_packing_Allwein_and_Biddle.pdf

It would help us in helping you if; you could explain why your interior walls need insulating. Is it for sound, to muffle noises/talking from one room to another? What is the sound source- stereo music, etc.? We need more information to help you reach the goal, but we need to know the "goal" first.

Gary


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## MAD King (Dec 14, 2010)

Gary in WA said:


> MAD King, I see looking at your other posts that you are from Germany? Welcome to the forums! "Dense-packing" cellulose is an installation procedure when insulating; http://www.karg.com/pdf/Insulaton_density/Dense_packing_Allwein_and_Biddle.pdf
> 
> It would help us in helping you if; you could explain why your interior walls need insulating. Is it for sound, to muffle noises/talking from one room to another? What is the sound source- stereo music, etc.? We need more information to help you reach the goal, but we need to know the "goal" first.
> 
> Gary


First let me thank you for the excellent link.

Second it is for soundproof and the sound it TV and sometimes talking. Even quiet talking. I am maybe a little bit sensitive with that.


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## Gary in WA (Mar 11, 2009)

You're welcome. I did a quick search on our forum, in the white-colored search box at the top of each page; http://www.diychatroom.com/search.php?searchid=3952689

We also have a resident sound-proofing pro on hand, perhaps he will chime in...

Here is some info to read while waiting; http://www.stcratings.com/assemblies.html

https://docs.google.com/viewer?a=v&...8LJcYA&sig=AHIEtbRCejFwR-ylH22k9KFLu0kks2AUwA

Gary


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## Ted White (Jun 23, 2009)

You wouldn't want to pack insulation for soundproofing purposes. Any packed / dense insulation will allow conduction of the vibration. Exactly what we're looking to avoid. 

Best to look at some decoupled mass. That would make a big difference. Even on its best day insulation doesn't add a lot.


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## MAD King (Dec 14, 2010)

@Gary

the first link gives me this back:


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Sorry - no matches. Please try some different terms.
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Bookmarked the other links.

@Ted

decoupled mass means that I have to re-do all the walls to separate them


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## Ted White (Jun 23, 2009)

Decoupling would mean a re-do, yes. Decoupling is a big aspect of sound isolated systems.


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## asinsulation (Apr 11, 2011)

you need to decide what you want to do first. I clearly asked for thermal or sound, and you said both, but that wasn't the question. So you were given the best solution to get a little of both, then switch it and say you just want soundproofing.

If you would truly like good, useful, and applicable advice, we need to know what you are trying to accomplish!


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## MAD King (Dec 14, 2010)

asinsulation said:


> you need to decide what you want to do first. I clearly asked for thermal or sound, and you said both, but that wasn't the question. So you were given the best solution to get a little of both, then switch it and say you just want soundproofing.
> 
> If you would truly like good, useful, and applicable advice, we need to know what you are trying to accomplish!


I think after reading the links from Ted I will go with the recoupling method. Should be that difficult for one room.


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