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In Wall Speakers and Insulation

post #1 of 19
Thread Starter 
So i did some research, but im paranoid so i wanted to double check.

I know nothing about insulation/etc...

It looks like i have Fiberglass insulation? I ripped out a small bit of it where my speaker was going to get it in. My question is should i cut all the insulation in the speaker mount area away? Im worried about the fiberglass potentially contacting some of the electronics on the backside of the speaker because its open and the insulation tends to expand out and will probably be resting across the entire backside of my Polk RC65i's

Heres some images, im worried both about the fiberglass being flammable from the heat the speaker electronics make, and im going to assume its not conductive so i dont need to worry about it shorting my speakers? All of the leads more or less look like they are protected except the ones on the big giant resistor/varistors.



post #2 of 19
i have the same question i am afraid of that on my HT i am about to set up... but i found This

it is a enclosure and is fire rated... maybe you can find something similar or build an enclosure or take it out....
post #3 of 19
Paradigm now lists several fireproof back boxes (fire-resistant would be a better description as they "only" have a 1-hour rating):
http://www.paradigm.com/products/products-by-category/in-wall-in-ceiling

Not sure how well they would fit speakers from other manufacturers.

Polk offers no such option?

I would be most worried about the paper backing catching fire when exposed to heat for extended periods of time (hence the warning about recessed light fixtures you can read in the picture). If this is on an interior wall you might consider removing the insulation, which I would not recommend for an exterior wall. You could look at Roxul insulation as an alternative.
Edited by ZeGhostbear - 5/30/13 at 6:08am
post #4 of 19
Thread Starter 
Quote:
Originally Posted by ZeGhostbear View Post

Paradigm now lists several fireproof back boxes (fire-resistant would be a better description as they "only" have a 1-hour rating):
http://www.paradigm.com/products/products-by-category/in-wall-in-ceiling

Not sure how well they would fit speakers from other manufacturers.

Polks offers no such option?

I would be most worried about the paper backing catching fire when exposed to heat for extended periods of time (hence the warning about recessed light fixtures you can read in the picture). If this is on an interior wall you might consider removing the insulation, which I would not recommend for an exterior wall. You could look at Roxul insulation as an alternative.

Surely the backside of a speaker isnt going to get as hot as a light bulb fixture though. Why not remove the insulation if its an exterior wall? Its only like a 12" by 8" block, would that really kill my heating and cooling?
post #5 of 19
Quote:
Originally Posted by arsenic0 View Post

Surely the backside of a speaker isnt going to get as hot as a light bulb fixture though. Why not remove the insulation if its an exterior wall? Its only like a 12" by 8" block, would that really kill my heating and cooling?

I just pointed out the potential risk, so you are aware. All woofers (or tweeters for that matter) are designed with heat dissipation in mind, which should tell us something. I honestly have no idea how hard and for how long you would need to drive the speaker before it would start a fire, but paper starts smoldering at lower temperatures than a lot of other building materials.

Here in Ontario I would never sacrifice thermal insulation on an exterior wall for anything. Even relatively small areas with lacking or reduced coverage will leak significant amounts of energy in harsh climates. Assuming you are installing LCR speakers that would give you three cavities with (partially) missing insulation. Concrete block is a relatively poor insulator on its own. Not sure whether that is a concern to you in Oregon. Thinking about the temperatures inside an uninsulated wall in winter also makes me wonder whether the speaker will be within the specified operating temperature range.

If I were you I would look for a solution that lets me keep the insulation, but only you can ultimately decide what is right for you.

Have you contacted Polk about your installation? Maybe an installer can chime in?
post #6 of 19
Your speaker isn't going to ever get hot enough to catch anything on fire unless you push it with too much power for a long time. If you're that worried then just get some sort of fire resistant material and put it behind the speaker. I would also replace the insulation you took out. It's more important to your house insulation envelope. The back of the speaker will just compress it.
post #7 of 19
Quote:
Originally Posted by ZeGhostbear View Post

I just pointed out the potential risk, so you are aware. All woofers (or tweeters for that matter) are designed with heat dissipation in mind, which should tell us something. I honestly have no idea how hard and for how long you would need to drive the speaker before it would start a fire, but paper starts smoldering at lower temperatures than a lot of other building materials.
+1, and the heat retention provided by the insulation could also lead to the voice coil overheating and failure.
Quote:
Here in Ontario I would never sacrifice thermal insulation on an exterior wall for anything. Even relatively small areas with lacking or reduced coverage will leak significant amounts of energy in harsh climates. Assuming you are installing LCR speakers that would give you three cavities with (partially) missing insulation. Concrete block is a relatively poor insulator on its own.
Concrete block might as well be classified as a conductor of heat, and therefore it also creates condensation problems, in any climate. I'd never use in wall speakers on exterior walls.
post #8 of 19
I've never seen a voice coil heat up very much except when its played really loud for hours on end. Does a voice coil really heat up that much at normal listening levels? How many of us have used fiberglass insulation in our DIY speaker cabinets?
post #9 of 19
Quote:
Originally Posted by flyng_fool View Post

I've never seen a voice coil heat up very much except when its played really loud for hours on end. Does a voice coil really heat up that much at normal listening levels? How many of us have used fiberglass insulation in our DIY speaker cabinets?

Please note that I was expressing concern about the paper backing catching on fire not the fiberglass. That is how fires in walls start and spread.

I will defer to speaker experts like Bill on how the speaker parts would behave.
post #10 of 19
Quote:
Originally Posted by ZeGhostbear View Post

Please note that I was expressing concern about the paper backing catching on fire not the fiberglass. That is how fires in walls start and spread.
.
+1, and if you remove the paper vapor barrier you're inviting rot.
post #11 of 19
Sorry Bill, but there you're wrong. This happens to be my area of expertise. The paper barrier does act as a vapor barrier, but it is a very poor one. If the vapor barrier is a concern, then you can get a peice of Tyvek which carries a Class 1 fire rating. Then you can still have your insulation there and not worry about anything catching on fire. You're not going to damage your house envelope f you take care to seal it back up before you put the speaker in.
post #12 of 19
Quote:
Originally Posted by flyng_fool View Post

Sorry Bill, but there you're wrong. This happens to be my area of expertise. The paper barrier does act as a vapor barrier, but it is a very poor one. If the vapor barrier is a concern, then you can get a peice of Tyvek which carries a Class 1 fire rating. Then you can still have your insulation there and not worry about anything catching on fire. You're not going to damage your house envelope f you take care to seal it back up before you put the speaker in.
A vapor barrier must be placed between the living area and the insulation. If that is not done then in cold weather moisture from inside the house will migrate through the insulation, and when it reaches the cold exterior wall it will condense, leading to eventual dry rot. Where it condenses within the insulation making the insulation damp it transforms the glass from an insulation to a heat conductor. If you take care to replace the vapor barrier all well and good, but most homeowners are unaware of its importance and fail to do so. Kraft paper and aluminum faced kraft paper barriers may not be the best possible vapor barriers, but they do work. If a totally impermeable material, like polyethylene sheet, was used the house could be too tight. You don't want free transfer of moisture, but some air transfer through the walls is beneficial.
post #13 of 19
That is why I suggested the Tyvek barrier. It does much better job than Kraft paper, and has a fire rating to boot. He can just replace the paper with Tyvek and he'll be good as far as having a vapor barrier. Also, not having that little bit would most likely not lead to large problems of moisture migration. It's too small of an area to have much of an effect.

Also, most polyethylene vapor barriers will allow migration of water vapor, but not liquid water.

Kraft paper is relatively useless as a vapor barrier.
Quote:
Types of Vapor Retarders
Any material that has a perm rating of 1 or less is considered to be an adequate vapor retarder for residential construction. (A perm rating is a measure of the diffusion of water vapor through a material.) The table below shows the perm rating of some common building materials that are consistent with the ASHRAE Handbook of Fundamentals and other industry sources.

Vapor Retarders and Perm Ratings

Insulation Facing, Kraft 1.0
1/4 inch Plywood (douglas fir, exterior glue) 0.7
Insulation Facing, Foil Kraft Laminate 0.5
Vapor Retarder Latex Paint, 0.0031 inch thick 0.45
0.002 inch Polyethylene Sheet 0.16
0.004 inch Polyethylene Sheet 0.08
0.0006 inch Polyethylene Sheet 0.06
Aluminum foil 0.00035 inch thick 0.05
Aluminum foil 0.001 inch thick 0.01

Not Vapor Retarders Perm Rating

3/8 inch gypsum Wall Board (plain) 50
4 inch Unfaced Mineral Wool 30
Typical Latex Paint — 0.002 inch thickness 5.5 to 8.6
4.4 lb/100ft2 Asphalt Saturated Sheathing Paper 3.3
post #14 of 19
I have a paper vapor barrier in my external walls. If one did tear it and wanted to tape it up, is there any particular tape that's recommended? Simple masking/painters tape? Duct tape?

Thanks,
Justin
post #15 of 19
I built enclosures for my in wall speakers and never gave a thought that they would create enough heat to cause a fire. I took the paper facing off the insulation and put it in my enclosures because that's how I seen speakers made. They do sound great.
post #16 of 19
Quote:
Originally Posted by justinmiller621 View Post

I have a paper vapor barrier in my external walls. If one did tear it and wanted to tape it up, is there any particular tape that's recommended? Simple masking/painters tape? Duct tape?

Thanks,
Justin
I would think just about any tape would be OK. Masking tape would probably work best.
post #17 of 19
I also built in wall boxs,I used 2x4's poly foam and instead sheet rock used 1/2" mdf ,I screwed the mdf inplace,taped texture painted, these are my rears. They sound excellent. If your on a exterior wall is use the tyvek and spray foam.. you could also use the Enwall wall insulator..
I'll load some more pics later. If your really concerned i would remove a portion of rock from stud to stud and do what I did.. it wont catch fire, this is low voltage and of your speakers are getting hot something wrong with your system.
post #18 of 19
Quote:
Originally Posted by justinmiller621 View Post

I have a paper vapor barrier in my external walls. If one did tear it and wanted to tape it up, is there any particular tape that's recommended? Simple masking/painters tape? Duct tape?

Thanks,
Justin

Duct tape will dry out and turn brittle over time. It is not suitable for most permanent fixes. Masking tape has weak adhesive (so you can remove it easily) and is not suitable for staying on anything long-term I would think.

There are specialized tapes that can be used for sealing vapor barriers. Tuck Tape makes something called "Sheathing Tape" for example.
post #19 of 19
I've had good masking tape last for years. Cheap tape won't last though.
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