# R38 insulation useful for front wall treatment?



## dogmatix (Nov 18, 2008)

Hello All,
I have two questions:

1. I recently completed a home re-insulation project, and have some of the R38 insulation (Certainteed) left over. I wondered whether the R38 could be useful treating the front wall of my basement Home Theater, which is basically an area of an otherwise open basement plan. The front wall of the HT area (12' wide x 7 ceiling ht.) is a simple framed single layer drywall, which separates my basement HT area from the adjoining Utility room, so it can easily be accessed for the "treatment". My obvious interest is to minimize both sound leakage from the HT area as well as minimize noise coming from the Utility room.

I recognize that soundproofing or sound isolation for my HT area is beyond my means, so I am exploring simple, seemingly common sense and inexpensive approaches.

2. In another discussion thread, I got very helpful suggestions on treating the ceiling. I subsequently found a pieces of foam carpet padding in my attic, and thought it might help dampen sound transmission via the tin ductwork, so I used it wrap as much of the ducts as possible. Before I invest in more of the padding, is this worth even the effort and $100 or so of padding I may need?

3. Finally, for an open basement plan, do I need to only focus on the air ducts in the immediate HT area or do I need to cover every linear foot of duct in the entire basement? 

Thank you.


----------



## bpape (Sep 14, 2006)

The R-38 would make excellent bass control in the front corners. It's a bit thick for my preference for the front wall if it's to be exposed to the room. Or, are you looking to put it behind the drywall? 

For the ducting damping, it will help a little bit but not a ton. You're slightly stopping the ringing if you wrap it tightly around it but doing nothing to tame transmission through it. 

If the plan is open, sound will enter and transmit through all of the ducting that has openings exposed to the large area.

Bryan


----------



## dogmatix (Nov 18, 2008)

Thanks, Brian. 
Yes, the plan is to insulate the front wall from the other side of the drywall, in the utility room, which is enclosed with a door so there will be no exposure from the HT area. 
If the R38 is good for that reason, should I consider placing some pieces behind/lying on top of the drop ceiling tiles overhead in the HT area, would that add any value?


----------



## bpape (Sep 14, 2006)

Still unsure - sorry. Are you going to have the R38 IN the ht room or on the other side of the wall?

Above the drop tiles, definitely insulate above there. It will help a bit with transmission and will act as a broadband bass absorber.

Bryan


----------



## dogmatix (Nov 18, 2008)

Bryan,
I wil be insulating the opposite side of the wall, or the side of the front wall on the opposite side of the HT area.
Regarding the ceiling insulation, the entire floor joists (above the basement ceiling and below the first floor subfloor, are insulated with R19 fiberglass. Would that be adequate?

Thanks.


----------



## bpape (Sep 14, 2006)

OK. Gotcha

The cavities behind with insulation will help a little in terms if mid and high frequency transmission. If no drywall on the other side, no real cavity to damp.

The R19 will do a decent job. I don't know how big the cavity is though between the tiles and the subfloor above the joists. 

Bryan


----------



## Rancho5 (Aug 20, 2009)

So from reading this post, can I assume that bat insulation can be used in place of OC 703 rigid panels? I have lots left over from my HT project and it would be much cheaper.


----------



## bpape (Sep 14, 2006)

In certain cases, yes. Thickness can be substituted for density in broadband usage.

To do side reflection panels, you'll want to compress it for space savings. On the front wall, you'd also need to or you'll potentially over extend the SBIR balance. Depends on the situation.

To get to a 3lb density, you'll need to compress standard wall insulation approx 4:1

Bryan


----------



## Rancho5 (Aug 20, 2009)

For this 4:1 ratio, I can just compress 8" thick fiberglass batts into 2" thick frames and get the density I need? If so, it would be quite a cost savings over those OC 703 panels I had planned to make.


----------



## bpape (Sep 14, 2006)

Yes - that's about right. It'll only take it to about 2.5lb/cu ft but that's close. If you look at the cost, it's not really that much different by the time you also add something to KEEP it compressed and not have them look like pillows.

Bryan


----------



## ScruffyHT (Sep 23, 2008)

dogmatix said:


> Bryan,
> I wil be insulating the opposite side of the wall, or the side of the front wall on the opposite side of the HT area.
> Regarding the ceiling insulation, the entire floor joists (above the basement ceiling and below the first floor subfloor, are insulated with R19 fiberglass. Would that be adequate?
> 
> Thanks.


If the front wall shared with the utility room is a 2 X 4 wall then the R38 is probably too thick to be useful as it will have to be compressed in order for you to drywall the utility room side of the wall. R13 would be better in that case. The best you are going to get in that situation anyway is to dampen that wall a bit but the flanking from the dropped ceiling will still allow the sound from the utility room to enter the theatre

As Bryan mentioned you can put the R38 up in the ceiling but this will only help with bass trapping not for sound isolation

In order to get better sound isolation you would probably have to look at doing a few things ... put acoustic flex ducting in place of the tin ducting ... double 5/8 drywall the ceiling and if you can spring it add greenglue as well ... do the same to the walls ... also use a solid core door with good weatherstripping and door sweep ... here is a example of a inexpensive door sweep http://www.hardwareandtools.com/invt/3505898

EDIT ... you already know all this from that other thread


----------



## dogmatix (Nov 18, 2008)

Bryan,
If one can sandwich the R38 between two panels of sheetrock, within a 2''x4'' framework, that would get the specs to 2" thick (from the 12" R38 thickness), and the only cost would be the drywall, don't you agree? Of course, that assumes the scenario I outlined is feasible which, in my case, it is.

Thanks.


----------



## dogmatix (Nov 18, 2008)

Thaks, Steve. You highlight a point of Bryan's I misinterpreted. When he saif the R38 would do an excellent job at the corners for bass trap, I thought he meant the corners with between the front wall and side wall. From your post, it is the ceiling and front wall corners? Please clarify for me.

Also, from reading the numerous posts on bass traps, I have a couple of questions for an audio novice:
Is "trapping the bass intended to increase the bass impact. If so, is the trap a cheaper alternative to getting a more powerful sub?

If not, for those folks with great audio equipment and "perfect" home theater setups who are still building and hanging bass traps on top of it all, what is the objective of the traps in those situations?

In my situation, I accept sound isolation is beyond my realm of possibility, but "bass control", if possible in my existing setup, would be much appreciated. I interpreted "bass control" to mean cleaner more impactful bass, or am I wrong? Bryan?


----------



## bpape (Sep 14, 2006)

You can certainly use the R-38 as IN-ROOM bass control to tighten things up. Compressing to smaller thicknesses will increase density but honestly, you'd be better off with less compression and more thickness for that application.

Sandwiching R-38 between drywall layers for treatment isn't going to be terribly effective. You'll have a very highly damped membrane type absorber. You'd be better off just leaving it open and maybe using some chicken wire to hold it in a slightly compressed state and then use cloth over that - especially on the front wall where you want full range absorbtion and not have it reflective in the upper mids and highs.

Bryan


----------



## dogmatix (Nov 18, 2008)

Okay. Got it. Thanks, Bryan. In that case, I will have to splurge on OC703/705s.

To clarify a point Steve raised, in his earlier post on this thread, did you mean ceiling treatment with the R38s would be a good idea? I already have a few batts, so would like to use them, if it will add value IN ADDITION to the 703.

When the 703s are installed, I will follow the guidelines you have provided others on this forum.

Thanks again.


----------



## bpape (Sep 14, 2006)

You can certainly make some thicker panels for the rear wall from the R38.

Bryan


----------



## dogmatix (Nov 18, 2008)

I just visited the GIK website, after reading one thread on room treatment. I hve decised to just buy one of the room kits from GIK. Trying to improvise and keep up with you guys is hurting my brain.

Your recommendation, Bryan, would be appreciated:

Again my BASEMENT room dimensions are: 12 feet wide and 30 feet deep, and a perfect rectangle. The side walls are the longer dimension and one of them opens up to the rest of the basement (total basement square footage is ~ 850 sq.ft). The other longer side is the exterior basement wall (concrete wall, then styrofoam, then drywall). The 12 ft front wall adjoins the utility room, and is a single panel of drywall, easily accesible from the utility room. The rear wall has closets spanning the entire width. Closts are about 4 ft deep.
I am wired for 7.1 and have the SVS PB Ultra.

Based on this what GIK kit would you recommend?

Thanks.


----------



## bpape (Sep 14, 2006)

You can still use the R-38 up above the drop ceiling for additional bass control.

As for a specific GIK recommendation, not sure one of the kits is your best option. I'd do:

2 pair Tri Traps for the corners

6 242 panels - 3 on each side wall for reflections and general decay time control.

Kill the balance of the front wall with 2" 703 and cover with GOM.

2 244 panels centered on the rear wall of the room.

Bryan


----------



## dogmatix (Nov 18, 2008)

Thank you.
To hide speaker cables and to flush the TV and tower speakers, the plan is to hang dark (and heavy?) drapes in front of the front wall. Would that adversely affect any of these panels and installations you recommend?
Also, since one side of my room opens up to the rest of the basement around the seating area (~12ft-15ft from the TV), I cannot use any 242, unless you have other ideas as to where they should go.

Thanks.


----------



## bpape (Sep 14, 2006)

OK. Drapes on the front wall will be fine.

If you have no wall on one side, skip 1 set of 242's and just do the wall opposite the opening.

Bryan


----------



## dogmatix (Nov 18, 2008)

Thanks again, Bryan.


----------

