Need Quick Answer (plastic Over Insulation)

[David Gaudreau]

NEED QUICK ANSWER (PLASTIC OVER INSULATION)
I went by my house last night to check on the progress and I noticed they had the whole interior of the theater room covered in plastic over the insulation.
I thought that it is better not to have a layer of plastic over the insulation because it will tend to reflect instead of absorb?
Is this true or not true? Will it be more effective covered or uncovered?

 

[ParadigmDawg]

Is this insulation behind the sheetrock?

 

[David Gaudreau]

Is this insulation behind the sheetrock?

Yes

I noticed that the back and side walls have no plastic on them, only the front wall and ceiling.

 

[David Gaudreau]

a few more pictures.

 

[mtrycrafts]

Yes

I noticed that the back and side walls have no plastic on them, only the front wall and ceiling.

I bet those walls are outside walls? If so, that is for moisture/vapor control in humid climates?
Ask the builder. I would recommend leaving it up as the sound transmission, if affected, would not matter with outside walls.

 

[David Gaudreau]

Alright, Thanks. I had them do all the walls and ceiling, to help keep in the sound.

 

[mtrycrafts]

Alright, Thanks. I had them do all the walls and ceiling, to help keep in the sound.

You mean they are not outside walls? Then I don't know why they would use plastic to cover the insulation, not needed. I doubt it would hinder sound attenuation anyhow.

 

[Alex2507]

Perimeter walls get the plastis to keep condensation from mucking up the drywall from what I understand.. I don't do residential so I don't KNOW about the ceilings but it stands to reason that you need it if it's an attic that is not under heat or a/c. That's as quick as it gets for me.

 

[Glenn Kuras]

NEED QUICK ANSWER (PLASTIC OVER INSULATION)
I went by my house last night to check on the progress and I noticed they had the whole interior of the theater room covered in plastic over the insulation.
I thought that it is better not to have a layer of plastic over the insulation because it will tend to reflect instead of absorb?
Is this true or not true? Will it be more effective covered or uncovered?

True for inside of the room when on early reflections, but inside of the wall it is fine. Any sound that is not stopped by the drywall is NOT going to be stopped (reflect) by a piece of plastic.

Glenn

 

[David Gaudreau]

Thanks, I did not know that they don't normally insulate the interior wall in a house. They normally only do exterior. One thing I noticed standing in the middle of my HT room is how dead it sounds with 360 degrees of insulation around you.

 

[mtrycrafts]

Thanks, I did not know that they don't normally insulate the interior wall in a house. They normally only do exterior. One thing I noticed standing in the middle of my HT room is how dead it sounds with 360 degrees of insulation around you.

Oh, yes, with just the insulation, it is rather dead but when the Sheetrock is on, well...

 

[mtrycrafts]

True for inside of the room when on early reflections, but inside of the wall it is fine. Any sound that is not stopped by the drywall is NOT going to be stopped (reflect) by a piece of plastic.

Glenn

Glenn, since you are here, he is also asking for help in placing panels:

http://forums.audioholics.com/forums/showthread.php?t=40012

 

[stratman]

Plastic is used as a vapor barrier only.

 

[mtrycrafts]

Plastic is used as a vapor barrier only.

Yes, that is why I asked if any wall is on the outside, otherwise, time to ask the contractor why he did it.