Tracking Room Ceiling Treatment

#1

Oh my, how the years go by.

I have finally achieved the isolation I've worked so hard for. It seems that it is time to pretty up the place, and to make it function the way I want it to. Enter acoustical treatment.

I recall from a long time ago, Stuart (I believe...) mentioning that it was feasible to use, in my case, r15 fluffy pink fiberglass insulation (covered in burlap) for 'absorption' in my live room ceiling modules (2x4 frames with 5/8" DD+GG on top)?

Being that my rectangular room is just about 1100 cubic feet (149" x 124" x 96"), I have troublesome modal issues in the lower frequency spectrum, predictably. For my room, I would imagine that fluffy pink is inferior to, for example, Owens Corning Thermafiber rockwool, of the same thickness.

Am I correct in thinking that the more dense rockwool would be ideal here?

Any thoughts or recommendations? Thanks in advance!

-Chris

#2

...yes, from Stuart's 'Inside-Out Ceiling" thread.

"The insulation is then installed in the empty bays under the modules, as part of the acoustic treatment for the room, with fabric below that to create the final visual ceiling for the room. The blue "tape" visible here is actually tough nylon packing strapping, used to keep the insulation in place. Note how the strapping is stapled to the sides of the framing, to prevent the insulation from touching the fabric below. If the insulation sags down and touches the fabric, it would create ugly bulges and bumps in the ceiling surface, but with the strapping done correctly there's a small gap between the insulation and the fabric, and the farbic ends up perfectly flat. -Soundman-"

The above is precisely my scenario and at this juncture, I am mainly curious of the method to determine the desired application for a given scenario, i.e. control room vs. live room, and rockwool vs. 'fluffy' fiberglass. When/why?

Acoustically speaking, I understand that pink fluffy is adequate for resonance control in between leaves, as a dense fill isn't necessary to achieve its function, but isn't really good for much else, attenuation-wise.

My small tracking room, where a Tama kit lives, is a low frequency nightmare; should I opt for more absorption in the ceiling modules and then attack the corners with traps afterward?

#3

depending on the joists overhead - say 2x10 - i might use R-19 (200mm) against the subfloor, compacted down by a layer of 3in (75mm) rockwool. using packing straps, chicken wire, insulation mesh etc across the joists to hold it in. then cover with cloth. then if you need MF and HF support you can selectively add panels and slats etc to restore those.

so layering from the top down on ceiling:

subfloor
R-19 9" (~225mm) ) (pink stuff)
3in (75mm) rockwool
retention wire/strap/mesh
cloth

(optional) panels / slats

#4

gullfo wrote:Source of the post depending on the joists overhead - say 2x10 - i might use R-19 (200mm) against the subfloor, compacted down by a layer of 3in (75mm) rockwool. using packing straps, chicken wire, insulation mesh etc across the joists to hold it in. then cover with cloth. then if you need MF and HF support you can selectively add panels and slats etc to restore those.

so layering from the top down on ceiling:

subfloor
R-19 9" (~225mm) ) (pink stuff)
3in (75mm) rockwool
retention wire/strap/mesh
cloth

(optional) panels / slats

Thanks for the reply, Glenn.

I'm unsure if I presented my situation well enough to be easily understood.

Without getting too technical in regard to my build specifically, I'll simply reiterate my main question, being that I'm torn between the decision to apply fluffy pink, vs. rockwool, to the 3 1/2" deep bays/acoustical faces of my inner leaf ceiling, a construct which consists of 6 of Stuart's "inside-out modules™️."

I suspect it is appropriate to refer to the above referenced insulative application as being acoustical 'treatment,' as it seems effectively no different than hanging a ceiling cloud of OC703 above a C/R's mix position, wouldn't you say?

Expanding on that theme, my bass-heavy live room, in my mind, would prosper from a rockwool ceiling wrapped in fabric vs. a pink fluffy ceiling wrapped in fabric, but in Stuart's "Inside-Out Module" thread, he specifically, though generically, says insulation wrapped in fabric, leading my thoughts down a hole.

For example, is there too much HF/MF absorption with an entire rockwool ceiling vs. fluffy pink?

Sorry to be so redundant, but we are talking acoustics here; there is never any room to make assumptions.

Cheers!

#5

no they would be expected to perform like a cloud - attenuate reflections and sound levels. given you're going to want to add some slats anyways (drums need some HF up there) i'd build the absorption down to the level of the deep cross beams. and use slats perpendicular to the beams to support it all. i don't think i'd restrict myself to the 3-1/2in depth. since it looks like some vents there - i'd make some extensions to stick through the deeply padded ceiling :-)

yes, the stacking i recommended should help R19 or even R30 compressed with a layer of 3-0in rockwool over it, then cloth & slats. nice soft pink insulation for the LF, and the rockwool layer for the MF and HF as well as impedance shift.

#6

Great response, Glenn, you nailed it. Apparently, I couldn't 'decipher' the simple clarity of your initial response.

gullfo wrote:no they would be expected to perform like a cloud - attenuate reflections and sound levels.

I visualized the ceiling more as a cloud, but used the term 'treatment', as you pointed out. Honestly, I never thought much of a difference between the two.

gullfo wrote:i'd build the absorption down to the level of the deep cross beams.

This is very insightful, and has also sparked a memory of having read about slightly compressing pink (about 30% ?) with a heavier absorption material below, if I'm not mistaken. Good advice!

gullfo wrote:i don't think i'd restrict myself to the 3-1/2in depth.

This will make my fabric application a breeze, compared to what I had planned prior, and I'll save some cash on finished wood.
I can finally get back to 'running down the road'. I'll be sure to drop in with updates.

I appreciate your time, Glenn, thanks a lot!

#7

Also, a tidbit of misunderstanding on my behalf...

gullfo wrote:Source of the postso layering from the top down on ceiling:

subfloor
R-19 9" (~225mm) ) (pink stuff)
3in (75mm) rockwool
retention wire/strap/mesh
cloth

(optional) panels / slats

...just to clarify something before moving on, I think r19 is 6"ish and r30 is 9"ish.

Would it be more beneficial (taming lows) to compress 9"ish of pink into the 3"-1/2" bays, and then rockwool, or the 6"ish pink and vice versa?

-Cheers!

#8

yep - you're right, definitely go with the R30

#9

R30 it is. Thanks for the clarification, Glenn!

Intriguing that compressed pink eats lows better than rockwool, I wouldn't have guessed that.

-Cheers!

#10

the longer fibers in the pink stuff tends to be more effective. and generally not compressing more than 50% usually increase the density slightly while still preserving a good GFR. another option when you have LF issues - add layer of 1lb/ft2 MLV between the pink and rockwool.

#11

What a pain in the arse.

The only 9" pink around here had paper (vapor barrier) facing, so I figured I'd just take it off, as pictured.

Having done this without being able to staple it up (pre-hanger mesh), I can't help but wonder what effect it would have to leave the kraft facing on and then to apply the mesh, if any?

I suspect it would make this task much easier.

Edit - I pulled off the paper, put on a rain coat, and went swimming in fiberglass. Good times. First layer installed.

#12

the paper can be used when you want a more reflective surface - however if you later don't want that, its tough to change. whereas external slats and panels can be added and removed as needed for the MF and HF support as well as diffusive effects.

#13

gullfo wrote:Source of the post yes, the stacking i recommended should help R19 or even R30 compressed with a layer of 3-0in rockwool over it, then cloth & slats. nice soft pink insulation for the LF, and the rockwool layer for the MF and HF as well as impedance shift.

Glenn do you recommend this for walls too? My current layering is exterior sheathing on 2x6 studs -> 2 layers 5/8" w/GG in the cavities -> 3" rockwool -> air gap -> 2x4 studs -> 3" rockwool -> 2 layers 5/8" w/ GG.

Should I pull the 3" from the outer wall and stuff some regular old R-19 pink fluffy in there and compress it down then add the 3" rock wool on top?

#14

you could just leave the rockwool and add the r-19 into the air gap. then the other rockwool on the inside wall

#15

gullfo wrote:Source of the post you could just leave the rockwool and add the r-19 into the air gap. then the other rockwool on the inside wall

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