Are there suggestions out there as to the best way to insulate newly installed speakers!  I have been working to improve the  tightness of my 22 year old home but after that big effort, I installed 10 speakers in 5 rooms.  This, as one might suspect, has resulted in several holes leading from unconditioned spaces to conditioned spaces. Some folks say just drape insulation over the new speakers while other say build a box to protect the innards of the speakers from fiber glass, dust, etc. The latter is supposed to enhance the quality of the music emanating from the speakers but there are many opinions out there!

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For the true audiophile, reversing the polarity causes the speakers to be "out of phase". No harmful effects other than the stereo or Home theater sound separation may be off- For most of us you will not hear the difference 

This is three different questions, air sealing, insulating, and acoustics/speaker performance.

Air sealing -- any air-impermeable sheet material, caulked or foamed into place, will provide a good air barrier. Drywall is commonly used, especially where fire resistance is needed. Pink or blue foam board (extruded polystyrene insulation board) is even easier to work, and insulates at the same time, but does not prevent fires from migrating into attics or walls. Tenmat light covers are NOT air--impermeable; don't use them is your goal is to air-seal.

Once you have a good air barrier, any insulation works -- stuff fiberglass batts evenlu and completely into the wall, lay them carefully and evenly over and around attic boxes. In attics, you can pour/fluff cellulose over the top of the box and just leave a big mound so that the insulation on top of the box is as good or better than the rest of the attic insulation.

Acoustic performance, on the other hand, is trickier. You get better bass frequency performance if a large (2 cubic feet or more ), airtight box is built around the back side of the speakers with the densest material possible. (Drywall, plywood, or OSB) The speakers are set with gaskets to make the box completely air tight. The trapped air acts like a "spring" behind the speaker diaphragm, so that it is more responsive to the electrical signal driving it. Mid- and high-frequency speakers don't care as much about having an air-tight enclosure, so failing to do it means the sound is less balanced -- a little less rich, more tinny and squeaky. It matters if you listen to rock or opera -- it won't matter if your tastes run to pop or rap.

If you really want to go esoteric/audiophile about all of this, there is a technique for enclosing bass speakers in an air-tight enclosure with a "port" in the face. If the hole of the port is just the right size, and a tube mounted into the hole is the right length, the out-of-phase bass from the speaker enclosure is brought back into phase and projected out of the front of the enclosure. You get more realistic sound at less volume and less power. This was a big deal with the monster stereo speakers your dad had in his dorm room so he could listen to Deep Purple "turned up to 11." More modern recording, mixing and balancing tecniques makes it less important. Those speakers the size of a paint can that you get at Best Buy and hang on the wall deliver very realistic sound at one-hundredth the size, because the circuits and enclosure are tuned very nicely. And they aren't depending on a hand-built enclosure to do that.




I read your response a couple of days ago and responded but must have missed the send button?!?!?  And thus I re-read it and noted that you mentioned fire resistance which really caught my eye after reading Dennis's response.  I shall ask the CanCoverIt folks what their fire resistance specs are but am not optimistic as I read nothing about fire resistance on their site but they tout their products as being air-tight so I may be partway there. Backer board seems like a great idea as it should be pretty dense, no?  And I figure I can build the boxes you suggested for the ceiling speakers about 15' x 15" x 15" which would come pretty close to 2 cu. ft.  I can do this as well for the wall speakers that back into attic space but have a couple that are in between walls so boxes will not work there. 

You also need to consider that if you have a fire,  the speaker and their boxes could be providing a chimney that enhances the spread of the flames.  If you make a box with foam - it should either have fire retardant properties OR use sheet rock, concrete backer board around it.   Another option is to use one of the foam products designed for use in custom built tile showers -- a layer of thinset is generally already attached to the foam.


Now that is a matter that I had given no thought to whatsoever!   I have not seen fire retardant foam -any thoughts about brands or sources?  While I am trying to simplify my life, it seems that is not to be.  I'll google fire retardant foam and custom built showers and see what I come up with.  Thanks for your input.  John

Look for large recessed can covers that are fire proof.   Tenmat makes some.   They might even be the perfect size for the speakers.

Also use a firestop foam or sealant.

There are lots of firestop products on the market.  For small installations like the speakers, buying small cans or tubes is a better deal.

I had looked at them about three or four years ago when I was trying to decide if I was going to just protect the old 1960's recessed cans in my house... try to make them air tight and safe for insulation.  In the end it was just easier to vacuum out the old insulation and replace with cans that were rated for air tight / incontact... 

Don Hynek alluded to Tenmat in his earlier post.   If you are trying to air seal,  glue down the Tenmats with a intumescent sealant,  then once set you can foam them in with an intumescent expanding foam -- common for use around pipes...

Can you give me a link for the fire resistant and intumescent products you are referring to? Do you know what specifications or tests they have passed? Most foam used as wall foam in houses today is flame spread 25, smoke less than 450. A few are flame spread 75. There is no good reason to use the FS75 materials given the availability of the FS25 materials. I wonder If the products you are using have no performance advantage over an FS25 foam?
All of the FS25 foams require a Thermal Barrier (1/2 inch gypsum board or equal) between them and living space. A TenMat is made of rock wool and it is 1/2 inch thick. I don't know of any testing saying they are, or are not as good as gypsum board, but I have seen multiple applications where the assembly of the gypsum box is questionable due to framing or wiring interrupting the box. The TenMats are much more adaptable.

There are quite a few different products available,  Touch'n Foam offers FireBreak.  Most trade supply stores will have them available.  Code often requires the gaps around wires and pipes to be sealed.  And you want to seal them to slow air leaks.

Generally you are looking for stuff that meets the UL-1715,  UL94, or various ASTM codes.

You can find hits by using phrase "flame resistant foam sealant" in a google search. 

Thanks to all who responded to my queries.  I believe I am now on the right path to seal my speakers and some can-lights without encouraging fires, fire chimneys, and poor speaker output.  Thanks again!  John 

I understand the reasoning of sealing the leaks, but I am not sure the products have any performance advantage. Everyone looks for marketing advantages. Some cold application (DIY) foams are FS75 materials, so if that manufacturer sells a FS25 material it will be more flme resistant than their base material. They would market that as 'flame resistant' but not say 'if compared to FS75 foam'. Flame Spread 25 foam still requires a thermal barrier. It cannot be part of a fire protection system. It would be a great contributor to the airsealing package though. Time is always limited, but I will look into this further.

The reason for using the sealant and foam ontop of the Tenmat hat is to address air leaks.  In some AHJ even low voltage wiring for stereos can be subject to inspection if they move between walls and attics.  It easier just to fire resistant stuff (nice orange color) and if any work on the house is inspected - most of the inspectors don't question the orange foam around  speaker boxes -- because it would meet local firecodes.  Speakers in ceilings and walls can be fire code violations - but the right kind of boxes and sealing solves those problems.

Foaming over the Tenmat might be overkill - but it does cut down the air leaks through the hats, it does add insulation value, and it makes the Tenmat hats a little more rigid.

John could build boxes out of plywood also -  3/4" plywood with minimal rock wool inside would also probably meet flame spread rules.   

John already has the speakers installed so at this point it is what is easiest, least cost, safest and stops air leaks...

UL1715 is a room fire test.  I don't know how applicable it is to sealing penetrations in otherwise fire resistant assemblies.  failure is indicated by fire escaping the room by penetrating walls or ceiling, or through the doorway in under 15 minutes. 

ASTM E 84 is the flame spread test.  It is limited in its validity for spray foam because spray foam has a relatively low self ignition temperature.  If you run an ASTM E84 test, you are testing surface burning characteristics, but in a building lined with foam, the foam holds the heat in very well (as always).  when the foam reaches ignition temperature you get flashover.  That is why the requirement for thermal barrier.  Again how applicable is that test to penetrations in otherwise fire resistant systems?

I could not find UL94, and did not see it indicated on data sheets I have for spray foam. 



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