Doing Massive DIY Room Treatment Project. Advice on how to keep the Fiberglass, fibers contained.

[rimmi2002]

Hi everyone,

Thank you for all the help so far. I shared my room details in earlier posts (Check out old post), and over the past several months I’ve been slowly building large porous absorption panels (definitely a major time sink).

Current plan:

(1) Corner / junction traps
• ~12–14 traps — 20" deep
• Size: 18"W × 50"H × 20"D
• Filled with 2 layers of R30 (10") Johns Manville fiberglass
• Placement: two room corners and all ceiling/wall junctions around the main listening area

(2) Rear-wall traps
• ~12–14 traps — 10" deep
• Size: 18"W × 50"H × 10.25"D
• Filled with 1 layer of R30 (10") Johns Manville fiberglass
• Arrangement: two stacked rows forming an L-shape behind the couch and extending along the wall to the left of the seating position

This is a mixed-use living space where we spend a lot of time, and there are ceiling fans in the room. My wife is understandably concerned about fiberglass exposure, and about eight panels will sit roughly 1–2 feet from our primary seating position.

Because of that, I’d like to add an extra acoustically transparent protective layer between the weed-block fabric and the final finish fabric to minimize any chance of fiberglass particles escaping.

Current layer plan (inside → outside):

1. Dalen Pro Shield weed block around the panel opening (Very Breathable Weed Block)
2. Two layers of 80/20 cotton/poly batting
3. Dalen Pro Shield weed block as the outer finish (we actually like the appearance)

My hope is that four total layers between the fiberglass and the room environment will provide sufficient protection.

Does this approach make sense, or is there a better material or method I should consider that maintains acoustic transparency while improving containment?

Pictures of some of the traps are below.

Thanks in advance for any advice!

 

[Wesseling Audio Lab]

Personally, I wouldn’t trust landscape fabric.
I’m using .5” cotton batting covering rockboard on entire surface of music room.
On some traps I built I used broadcloth on the back and batting on the front
Traps used for strictly bass traps could have broadcloth on the front as well

Fwi, air gaps between several thinner traps increases efficiency and brings it close to the absorption coefficient
of having the equivalent thick trap thickness. More about cost and probably solid deep units are easier to build.
Ref in master handbook on acoustics

 

[rimmi2002]

Personally, I wouldn’t trust landscape fabric.
I’m using .5” cotton batting covering rockboard on entire surface of music room.
On some traps I built I used broadcloth on the back and batting on the front
Traps used for strictly bass traps could have broadcloth on the front as well

Fwi, air gaps between several thinner traps increases efficiency and brings it close to the absorption coefficient
of having the equivalent thick trap thickness. More about cost and probably solid deep units are easier to build.
Ref in master handbook on acoustics

Thanks. Where did you get the 0.5" cotton batting? I ordered from simmonds, but its like 1/16 of a inch thick, and easy to compress to less, which I'm sure it does get compressed with you wrap a tight fabric over it.

I didn't do air gaps, because theoretically filling the same space with porous absorber leads to better absorption so I just filled them all the way.

Just down to the last step now on how to make them super safe yet effective. People have suggested wrapping them in thin plastic, but is not good for the ones behind me, they will reflect all high frequency sounds and that will be a problem. The system does sound really good / much better than before when I tested out the traps in their designated positions.

 

[Philbo King]

I used unbleached muslin to cover my absorbers. Worked great. It was the cheapest non-sheer fabric I could find at the time.

 

[Dj7675]

Personally, I wouldn’t trust landscape fabric.
I’m using .5” cotton batting covering rockboard on entire surface of music room.
On some traps I built I used broadcloth on the back and batting on the front
Traps used for strictly bass traps could have broadcloth on the front as well

Fwi, air gaps between several thinner traps increases efficiency and brings it close to the absorption coefficient
of having the equivalent thick trap thickness. More about cost and probably solid deep units are easier to build.
Ref in master handbook on acoustics

After going doing this road several years ago in my old theater I would reconsider…
This massive amount of fiberglass/traps…
-Is expensive
-time consuming to build
-Over absorption of high frequencies along with low frequencies
-Takes up tons of space that can be better used for other things
-May likely not achieve fully what you are hoping to achieve.
If the goal is trying to deal with your room, instead consider
-Multiple subwoofers to control/deal with room modes etc under 100-150hz. For example in all for corners, or 4 on midpoints
-Get a receiver/processor with Dirac ART
I did corner traps in all 4 corners (and other broad band absorption) and it had a much smaller affect than I needed below 100hz. Tried 4 subwoofers in corners and pulled out all the bass traps. Not only were the effect on room measurements huge, it sounded better, and with the removal I had more room for seating etc.
Just my two cents..

 

[Wesseling Audio Lab]

Thanks. Where did you get the 0.5" cotton batting?

I haven't purchased yet. Amazon has it. I need closer look as there might be a closed sheet on the surface that I wouldn't want